JP7781675B2 - Wireless device, system, method and program - Google Patents

Description

Embodiments of the present invention relate to wireless devices, systems, methods, and programs.

In recent years, industrial robots have been used in factories, warehouses, and other places to improve work efficiency.

When controlling the operation of at least a portion of such an industrial robot (hereinafter referred to as the controlled object), it is desirable to use wireless communication to avoid the hassle of wiring and the risk of wire breakage.

However, when controlling a control target using wireless communication, there is a possibility that the wireless communication may deteriorate depending on the operation of the control target or the environment in which the control target operates, making it difficult to maintain the quality of control over the control target.

Japanese Patent Application Laid-Open No. 2017-228917

The problem that this invention aims to solve is to provide a wireless device, system, method, and program that can suppress deterioration in the quality of control over controlled objects using wireless communication.

According to an embodiment, a wireless device for controlling a control object using wireless communication is provided. The wireless device includes a receiving means, a first acquiring means, an estimating means, a transmitting means , and a measuring means . The receiving means receives a status signal including status information indicating a status of the control object. The first acquiring means acquires a target control value of the control object. The estimating means estimates deterioration of the wireless communication after a predetermined period has elapsed based on the received status signal and the acquired target control value. The transmitting means transmits a control signal including control information for controlling the operation of the control object in accordance with a control method for the control object selected based on the estimation result. The status signal includes a first status signal including first status information and a second status signal including second status information indicating a state of the control object transitioned from a state of the control object indicated by the first status information. The target control value includes a first target control value acquired when the first status signal is received and a second target control value acquired when the second status signal is received. The measuring means measures a first radio characteristic related to the wireless communication from the received first status signal, and measures a second radio characteristic related to the wireless communication from the received second status signal. The estimating means estimates the radio characteristic after a predetermined period has elapsed based on the measured first and second radio characteristics and the acquired first and second target control values, and estimates that the wireless communication has deteriorated if the estimated radio characteristic is smaller than a threshold.

FIG. 1 is a diagram for explaining an example of a wireless control system according to a first embodiment. FIG. 1 is a block diagram showing an example of the configuration of a wireless device. 10 is a flowchart showing an example of a processing procedure of a wireless device. FIG. 10 is a diagram for specifically explaining the deterioration estimation process. FIG. 10 is a diagram showing an example of the data structure of a deterioration estimation table. FIG. 10 is a diagram showing another example of the data structure of the deterioration estimation table. FIG. 10 is a block diagram showing an example of the configuration of a wireless device according to a second embodiment. 10 is a flowchart showing an example of a processing procedure of a wireless device. 5A and 5B are diagrams for specifically explaining the position calculation process performed by a position calculation unit; FIG. 11 is a block diagram showing an example of the configuration of a wireless device according to a third embodiment. 10 is a flowchart showing an example of a processing procedure of a wireless device.

Hereinafter, each embodiment will be described with reference to the drawings.
(First embodiment)
First, a first embodiment will be described. Fig. 1 is a diagram illustrating an example of a wireless control system including a wireless device according to this embodiment. In the example shown in Fig. 1, the wireless control system includes a wireless device 10 and a SCARA robot 20.

The wireless device 10 is equipped with a wireless communication device capable of wireless communication with an external device via an antenna, and has, for example, the function of modulating information to be transmitted from the wireless device 10 to an external device to generate a wireless signal, and the function of demodulating wireless signals received from an external device to extract various information (modulation/demodulation function). The wireless device 10 may also have a CPU and memory (main memory, non-volatile memory, etc.), and may have computer functions for processing information (data) transmitted and received via wireless communication.

The SCARA robot 20 is a type of industrial robot that has multiple motors (rotational axes) and can move a movable part called an arm horizontally, and is also called a horizontal articulated robot. Figure 1 shows the SCARA robot 20 positioned on the X-Y plane in three-dimensional space defined by the X, Y, and Z axes.

The SCARA robot 20 comprises a base 21, a first arm 22, a second arm 23, and a gripper 24. The base 21 also contains a first motor 211. The second arm 23 also contains a second motor 231.

The base 21 is fixedly disposed on, for example, the floor or a table (desk). The first arm 22 is connected to the base 21 via a first motor 211 built into the base 21. As a result, the angle of the first arm 22 relative to the base 21 can be changed by rotating the first motor 211.

The second arm 23 is also connected to the first arm 22 via a second motor 231 built into the second arm 23. This allows the angle of the second arm 23 relative to the first arm 22 to be changed by rotating the second motor 231.

The gripper 24 has the function of grasping, for example, an object (item). Although a detailed explanation will be omitted, the gripper 24 may operate to pinch an object detected by, for example, a proximity sensor, or may operate to suck the object using a suction point, etc.

With this type of SCARA robot 20, the angles of the first arm 22 and the second arm 23 can be controlled in accordance with the rotation of the first motor 211 and the second motor 231, allowing the gripper 24 to be moved to any position within its movable range, and the gripper 24 can be used to perform tasks (work), such as transferring objects moving on a conveyor belt installed in a factory onto a tray (i.e., picking luggage).

Here, in the SCARA robot 20 shown in Figure 1, the first motor 211 is connected to the first wireless device to be controlled 212 by wire, and the second motor 231 is connected to the second wireless device to be controlled 232 by wire.

The first control-target radio device 212 and the second control-target radio device 232 are equipped with a wireless communication device capable of wireless communication with external devices via an antenna, and have modulation and demodulation functions similar to the wireless device 10 described above. The first control-target radio device 212 and the second control-target radio device 232 may also be equipped with a CPU and memory (main memory, non-volatile memory, etc.), and may have computer functions for processing information (data) transmitted and received via wireless communication.

According to this, the wireless device 10 described above can control (the operation of) the SCARA robot 20 by wirelessly communicating with the first control target wireless device 212 and the second control target wireless device 232. Specifically, the wireless device 10 generates control signals by modulating control information for controlling, for example, the first arm 22 (first motor 211) and the second arm 23 (second motor 231), and transmits the control signals to the first control target wireless device 212 and the second control target wireless device 232. The first control target wireless device 212 and the second control target wireless device 232 demodulate the control signals transmitted from the wireless device 10 to extract the control information, and control the first arm 22 (first motor 211) and the second arm 23 (second motor 231) in accordance with the control information. While the case where the first arm 22 and the second arm 23 are controlled in accordance with the control information is assumed here, the gripper 24 may also be controlled in accordance with the control information.

Furthermore, the first control target wireless device 212 and the second control target wireless device 232 modulate status information indicating the status of the SCARA robot 20 (e.g., the first arm 22 and the second arm 23) to generate a status signal, and transmit the status signal to the wireless device 10.

The above-mentioned status information is a sensor value measured by an internal sensor (or encoder) attached to the SCARA robot 20, and the status of the SCARA robot 20 indicated by this status information includes, for example, the angles of the first arm 22 and the second arm 23. The status information may also be, for example, a value measured by a Hall sensor (a quantized value of an electrical signal) or a parameter value set for the SCARA robot 20.

The first motor 211 and second motor 231 can convert electric power into rotational motion, for example, and the movement and position of the first arm 22 and second arm 23 are determined by the rotation speed (encoder value) of the first motor 211 and second motor 231. Therefore, the first motor 211 and second motor 231 can be said to function as sensors for determining the angles of the first arm 22 and second arm 23 (or the positions of the gripper 24, first control target wireless device 212, and second control target wireless device 232). In this case, the encoder values (sensor values) of the first motor 211 and second motor 231 may be used as status information. Furthermore, the status information may be values measured by a gyro sensor or the like built into the first arm 22 and second arm 23, for example.

As described above, the wireless device 10 demodulates the status signals transmitted to the wireless device 10 from the first control-target wireless device 212 and the second control-target wireless device 232 to extract status information, and from this status information, can determine the angles of the first arm 22 and the second arm 23, as well as the positions of the first motor 211, the first control-target wireless device 212, the second motor 231, the second control-target wireless device 232, and the gripper 24. Note that the positions determined from the status information can be expressed, for example, based on a coordinate system defined within the wireless control system. Furthermore, the status signals transmitted to the wireless device 10 from the first control-target wireless device 212 and the second control-target wireless device 232 may be used to generate control information for controlling the first arm 22 (first motor 211) and the second arm 23 (second motor 231).

Note that while Figure 1 illustrates a wireless control system equipped with a SCARA robot 20, the wireless control system may also be configured to include industrial robots other than the SCARA robot 20.

In addition, in this embodiment, the wireless communication method for transmitting and receiving control information (control signals) and status information (status signals) is assumed to be a wireless LAN (Local Area Network), but it may also be based on other standards, such as ZigBee (registered trademark) and local 5G. Furthermore, in this embodiment, wireless communication based on a proprietary standard may also be performed.

Furthermore, the control signal may be transmitted as a unicast signal to one of the first controlled radio device 212 and the second controlled radio device 232, or as a broadcast signal to both the first controlled radio device 212 and the second controlled radio device 232.

The status signal may be transmitted as a unicast signal to the wireless device 10, or as a broadcast signal to the wireless device 10 and all other controlled wireless devices. Upon receiving the unicast signal, the wireless device 10 may return an acknowledgment using an ACK frame or the like to the controlled wireless device that transmitted the unicast signal. In this case, if an acknowledgment is not received from the wireless device 10, the controlled wireless device may retransmit the status signal (transmission signal).

Furthermore, although two motors (first motor 211 and second motor 231) are shown in Figure 1, the SCARA robot 20 may be equipped with any number of motors. The same applies to the wireless device to be controlled.

In addition, while Figure 1 illustrates one controlled wireless device controlling one motor, one controlled wireless device may also be configured to control multiple motors. In this case, for example, if identification information (hereinafter referred to as a motor ID) for identifying a motor is specified as the destination of a control signal (control information) transmitted from wireless device 10, the controlled wireless device can control the motor identified by the motor ID.

In addition, although FIG. 1 illustrates a wireless control system equipped with one SCARA robot 20, the wireless control system may also be equipped with multiple SCARA robots 20. If the wireless control system is configured to be equipped with multiple SCARA robots 20, the wireless control system may also be equipped with one or more wireless devices 10 for controlling the multiple SCARA robots 20.

Next, Figure 2 is a block diagram showing an example of the configuration of a wireless device 10 according to this embodiment. The wireless device 10 according to this embodiment has the function of controlling a control target using wireless communication. In the following description, the control target may be, for example, the SCARA robot 20 itself shown in Figure 1, or at least a part of the SCARA robot 20 (at least one of the first arm 22, second arm 23, first motor 211, second motor 231, first control target wireless device 212, second control target wireless device 232, and gripper 24). Note that although Figure 2 shows only one control target, there may be multiple control targets.

In this embodiment, control information is digital information for controlling a controlled object, and a control signal is a high-frequency signal (i.e., a wireless signal including control information) or a baseband signal generated by modulating the control information. In this embodiment, status information is digital information representing the status of a controlled object, and a status signal is a high-frequency signal (i.e., a wireless signal including status information) or a baseband signal generated by modulating the status information.

As shown in FIG. 2, the wireless device 10 includes a wireless unit 11 and a processing unit 12, and is configured to receive the above-mentioned status signal from the controlled object and to transmit the above-mentioned control signal to the controlled object.

The wireless unit 11 receives a status signal, which is a wireless signal, from the controlled object, for example. The wireless unit 11 demodulates the received status signal and extracts the status information.

In addition, the radio unit 11 receives control information for controlling the controlled object from the processing unit 12 and modulates the received control information to generate a control signal. The radio unit 11 transmits the generated control signal to the controlled object.

Furthermore, the wireless unit 11 includes a wireless characteristic measurement unit 111. The wireless characteristic measurement unit 111 measures the wireless characteristics related to the wireless communication used to control the control target from the status signal received from the control target.

In this embodiment, the wireless unit 11 is implemented using hardware such as an antenna and a wireless communication device, but part of the wireless unit 11 may also be implemented using software.

The processing unit 12 includes a control information generation unit 121 and a deterioration estimation unit 122. The control information generation unit 121 acquires (inputs) a target control value (external control information) of a control object managed in, for example, a device external to the wireless device 10 from the external device. Note that the target control value acquired by the control information generation unit 121 is a target angular velocity or the like when the control object is, for example, the first arm 22 or the second arm 23 shown in FIG. 1, but may also be another value.

The control information generator 121 may acquire a target control value that is pre-stored in a device external to the wireless device 10, or may acquire a target control value that is created by a predetermined program running in the external device. Furthermore, the control information generator 121 may acquire a target control value in response to an operation (command) by an administrator or the like on the external device. This operation by an administrator or the like may include, for example, pressing a button to issue an emergency stop to the operation of the controlled object.

The degradation estimation unit 122 estimates the degradation of the wireless communication used to control the control object based on the status signal received by the wireless unit 11 and the target control value acquired by the control information generation unit 121. In this case, the degradation estimation unit 122 estimates the degradation of the wireless communication using the wireless characteristics measured from the status signal by the wireless characteristic measurement unit 111 as described above. Note that in this embodiment, degradation of the wireless communication refers to a decrease in the quality of the wireless communication to the extent that it affects the control of the control object using the wireless communication.

The control information generation unit 121 selects a control method for the control object based on the estimation results by the degradation estimation unit 122, and generates control information for controlling the control object in accordance with the selected control method. The control information is generated based on target control values obtained from an external device, for example, but may also be generated using status information extracted from a status signal by the radio unit 11. The control information generated in this manner is modulated by the radio unit 11 and transmitted to the control object as a control signal. In this embodiment, the control signal is transmitted at a predetermined control period, but the control period may be changed as appropriate.

When a control signal is transmitted from wireless device 10, the controlled object is controlled based on the control information extracted from the control signal by demodulating the control signal, and transmits a status signal to wireless device 10 by modulating status information indicating the status of the controlled object. The status signal may be transmitted from the controlled object to wireless device 10 immediately after receiving the control signal, or may be transmitted from the controlled object to wireless device 10, for example, when a status information request message is received from wireless device 10. The status information may also be input to wireless device 10 via an external device as a piece of external control information.

The processing unit 12 is realized, for example, by one or more processors, and the control information generation unit 121 and degradation estimation unit 122 included in the processing unit 12 are realized by the processor executing a predetermined program, i.e., by software. However, some or all of the control information generation unit 121 and degradation estimation unit 122 may be realized by hardware, or by a combination of software and hardware.

Next, an example of the processing procedure of the wireless device 10 will be described with reference to the flowchart in Figure 3. Note that the processing shown in Figure 3 is executed for each control cycle described above. Here, the description will be given assuming that the control target is the second arm 23 shown in Figure 1.

First, assume that a control signal is transmitted from the wireless device 10 to the second controlled wireless device 232, and the angle of the second arm 23 is controlled by rotating the second motor 231 connected to the second controlled wireless device 232 based on a control signal extracted from the control signal, and a status signal including status information indicating the state (e.g., angle) of the second arm 23 (i.e., a status signal generated by modulating the status information) is transmitted from the second controlled wireless device 232.

In this case, the wireless unit 11 receives a status signal transmitted from the second controlled wireless device 232 (step S1). When the processing of step S1 is executed, the wireless unit 11 extracts status information from the status signal by demodulating the status signal received in step S1, and outputs the status information to the processing unit 12 (control information generation unit 121).

Next, the wireless characteristic measurement unit 111 included in the wireless unit 11 measures the wireless characteristics from the status signal received in step S1 (step S2). In step S2, the wireless characteristic measurement unit 111 measures, for example, the power level of the status signal as the wireless characteristic.

The status signal (received signal) includes a pilot signal (a signal with a predetermined pattern) that is used to correct for frequency offsets and the like when demodulating the status signal, and the radio characteristic measurement unit 111 may measure the power level of the pilot signal as the radio characteristic. Specifically, for example, in the case of IEEE 802.11a, a wireless LAN standard, each OFDM symbol includes four pilot subcarriers. In this case, the power level of each of the four pilot subcarriers included in the OFDM symbol may be measured, and the minimum of the measured power levels may be taken as the radio characteristic.

Furthermore, the wireless characteristic measurement unit 111 may measure, for example, the bit error rate or EVM (Error Vector Magnitude) in the status signal, and use the inverse of the measured bit error rate or the inverse of the EVM as the wireless characteristic.

The wireless characteristics measured in step S2 are output to the processing unit 12 (deterioration estimation unit 122).

When the processing of step S2 is executed, the control information generation unit 121 acquires a target control value for the second arm 23 from an external device as external control information (step S3). As described above, the target control value for the second arm 23 is, for example, a target angular velocity. The target control value acquired in step S3 is output to the deterioration estimation unit 122.

Next, the degradation estimation unit 122 performs a process (hereinafter referred to as the degradation estimation process) to estimate degradation of the wireless communication used to control the second arm 23 (i.e., the wireless communication with the second control target wireless device 232) based on the wireless characteristics measured in step S2 (the wireless characteristics output from the wireless characteristic measurement unit 111) and the target control value acquired in step S3 (the target control value output from the control information generation unit 121) (step S4).

The degradation estimation process performed in step S4 will be explained in detail below with reference to Figure 4.

In Figure 4, the vertical axis represents the radio characteristics, and the horizontal axis represents time. That is, Figure 4 shows the radio characteristics measured from the status signal received from the second controlled radio device 232 for each control period T. Note that the control period T is the period during which a control signal is transmitted to the second controlled radio device 232 (second arm 23). For example, the radio characteristics at time 4T shown in Figure 4 correspond to the radio characteristics measured from the status signal transmitted from the second controlled radio device 232 upon transmission of a control signal (control information) to the second controlled radio device 232 at time 4T. The same applies to the radio characteristics at other times. Note that while Figure 4 assumes that the radio characteristics are the power level of the status signal, the power level may be expressed in decibels or as a true value.

Here, if the wireless characteristic at time nT (n=1, 2, ...) is L(nT) and the target control value at time nT is S(nT), the deterioration estimation process is performed using the following equation (1), which is called the deterioration determination equation.
L(nT)+ΔL×m×ΔS<L _th formula (1)

In this formula (1), ΔL represents the difference between the wireless characteristics at time nT and the wireless characteristics at time (n-1)T (that is, ΔL = L(nT) - L((n-1)T)). Furthermore, m represents an estimation of the deterioration of wireless communication after a predetermined period, for example, a control period T x m, has elapsed. Furthermore, ΔS represents the ratio between the target control value at time nT and the target control value at time (n-1)T (that is, ΔS = S(nT)/S((n-1)T)). Furthermore, _Lth represents a threshold value (deterioration determination threshold value) for determining whether or not wireless communication has deteriorated.

The target control value S(nT) at time nT is the target control value used to generate the control information included in the control signal transmitted at time nT (i.e., the target control value scheduled to be transmitted). In other words, the target control value S(nT) at time nT is the target control value acquired when a status signal in which the radio characteristics at time nT are measured is received. On the other hand, the target control value S((n-1)T) at time (n-1)T is the target control value used when generating the control information included in the control signal already transmitted at time (n-1)T. In other words, the target control value S((n-1)T) at time (n-1)T is the target control value acquired when a status signal in which the radio characteristics at time (n-1)T are measured is received.

In addition, here it is assumed that the target control values S(nT) and S((n-1)T) are target angular velocities.

That is, according to the deterioration determination formula of the above-mentioned formula (1), the wireless characteristics after the period T×m from the present are estimated based on the wireless characteristics at time nT and time (n−1)T and the target control values at time nT and time (n−1)T, and it is possible to estimate that there is deterioration in wireless communication when the estimated wireless characteristics are smaller than the deterioration determination threshold value L _th .

Specifically, for example, when the degradation estimation process is executed at time 5T, m is 3 and ΔS is 1 (that is, the second arm 23 is rotating at a constant speed), at time 8T after the period T×3 has elapsed from the present (time 5T), it is determined that the wireless characteristics fall below L _th according to the degradation determination formula (1) described above, and therefore it is estimated that there is degradation in the wireless communication.

Here, we have explained that the degradation estimation process is performed at time 5T, but it is assumed that there is no degradation in wireless communication before time 4T.

The deterioration determination threshold _Lth used in the deterioration determination formula of the above formula (1) may be set based on a prior evaluation of the deterioration of the wireless characteristics, etc. Specifically, if it is determined from the prior evaluation that the wireless characteristics at which the quality of control of the controlled object (here, the second arm 23) begins to be affected are _Lng , _Lth can be set to satisfy Lth≧ _{Lng .}

Furthermore, taking into consideration the stability of control over the controlled object, it may be determined that there is no degradation in wireless communication without performing degradation estimation processing at the timing when the controlled object starts to operate (for example, S((n-1)T) = 0 and S(nT) ≠ 0) and the timing when the operating direction of the controlled object (the rotation direction of the second motor 231) switches (in other words, S(nT) x S((n-1)T) < 0). On the other hand, for example, when S(nT) = S((n-1)T) = 0, it may be possible to perform degradation estimation processing with ΔS = 1.

Note that the above-mentioned equation (1) is one example of a degradation determination equation, and the degradation estimation process may be performed using a different degradation determination equation. Specifically, while the degradation determination equation described here uses the wireless characteristics and target control values at time nT and time (n-1)T (i.e., the wireless characteristics and target control values for two control cycles), it is also possible to use a degradation determination equation that uses the wireless characteristics and target control values for time nT and time (n-m (m is an integer greater than or equal to 2))T, for example. Furthermore, by constructing a degradation determination equation that uses the wireless characteristics and target control values for, for example, three or more control cycles, it may be possible to estimate wireless communication degradation with greater accuracy.

Note that although the target control value is set to the target angular velocity S(nT), the target control value may also be set to the target position, and the target angular velocity calculated from that target position and status information may be set to S(nT).

When the processing of step S4 is executed, the degradation estimation unit 122 outputs the result of the processing of step S4 (i.e., the estimation result of whether or not there is degradation in wireless communication) to the control information generation unit 121.

Next, the control information generation unit 121 selects a control method for the second arm 23 based on the estimation result (hereinafter referred to as the deterioration estimation result) output from the deterioration estimation unit 122, and generates a control signal in accordance with that control method (step S5).

An example of the processing of step S5 will be described below. In this embodiment, the control information is generated based on the target control value acquired (input) from the external device described above. When the target control value is a target angular velocity, a method of generating control information including the target angular velocity as a target angular velocity _Vtgt1 is referred to as a first control method (first control information generation method). On the other hand, a method of generating control information including a target angular velocity _Vtgt1 × α as a target angular velocity _Vtgt2 is referred to as a second control method (second control information generation method). Note that 0≦α<1.

Here, if there is no degradation in the wireless communication used to control the second arm 23 (wireless communication with the second control-target wireless device 232) and good wireless communication can be established with the second control-target wireless device 232, control signals will be properly transmitted and received between the wireless device 10 and the second control-target wireless device 232 for each control period, and it is believed that it will be possible to accurately control the second arm 23 via the second control-target wireless device 232. On the other hand, if there is degradation in the wireless communication used to control the second arm 23 (wireless communication with the second control-target wireless device 232) and good wireless communication with the second control-target wireless device 232 cannot be established, the second control-target wireless device 232 may not receive the control signal for each control period, which could result in unintended operation of the second arm 23 (second motor 231).

Therefore, when the degradation estimation result indicating that there is no degradation in wireless communication is output from the degradation estimation unit 122, the control information generation unit 121 selects the first control method and generates control information including the target angular velocity _Vtgt1 acquired from the external device. On the other hand, when the degradation estimation result indicating that there is degradation in wireless communication is output from the degradation estimation unit 122, the control information generation unit 121 selects the second control method and generates control information including the target angular velocity Vtgt2 obtained by correcting the target angular velocity _Vtgt1 acquired from the external device so as to reduce the impact when the second controlled wireless device ₂₃₂ later fails to receive the control signal normally due to the degradation in wireless communication.

Specifically, controlled objects such as the second arm 23 are often configured to continue operating in accordance with the previous control signal until a new control signal is received. However, by selecting the second control method when it is estimated that there is degradation in wireless communication, it is possible to avoid the risk of unintended high-speed operation occurring if control information is no longer being sent and received properly.

Note that while the target control value here is a target angular velocity, the target control value may also be, for example, a target angle of the second arm 23 (target rotation angle of the second motor 231). In this case, the control information generator 121 generates control information based on the status information output from the wireless unit 11 and the target angle of the second arm 23 acquired from an external device. Note that the status of the second arm 23 indicated by the status information includes the current angle of the second arm 23.

In this case, if the current angle of the second arm 23 (the state of the second arm 23 indicated by the state information) is _{a_s} and the target angle of the second arm 23 is _{a_tgt} , the target angular velocity _{V_tgt1} of the second arm 23 is calculated by the following equation (2).
V _tgt1 = K _p × (a _tgt - _{a s} ) Equation (2)

In addition, _Kp in the equation (2) is a gain constant for calculating the target angular velocity for changing the current angle of the second arm 23 to the target angle of the second arm 23 .

When a target angle is acquired as the target control value, the method of calculating the target angular velocity using equation (2) can be set as the first control method (first control information generation method).

On the other hand, the second control method (second control information generation method) is a method for calculating the target angular velocity _Vtgt2 of the second arm 23 using the following equation (3).
V _tgt2 = α×K _p × (a _tgt − _{a s} ) Equation (3)

According to this, when the degradation estimation result indicating that there is no degradation in wireless communication is output from the degradation estimation unit 122, the first control method is selected and control information including the target angular velocity _Vtgt1 calculated by the above-mentioned equation (2) is generated. On the other hand, when the degradation estimation result indicating that there is degradation in wireless communication is output from the degradation estimation unit 122, the second control method is selected and control information including the target angular velocity _Vtgt2 calculated by the above-mentioned equation (3) is generated.

As described above, since the target angular velocity is used in the degradation estimation process (i.e., estimation of degradation of wireless communication), when the target control value is a target angle, the target angular velocity _Vtgt1 calculated by the above-described formula (2) is output to the degradation estimation unit 122, and the degradation estimation process is performed using the target angular velocity _Vtgt1 .

Furthermore, certain upper or lower limit values (limiters) may be applied to the above-described target angular _{velocities Vtgt1} and _Vtgt2 . In this case, different upper or lower limit values may be applied to the target angular velocities _Vtgt1 and _Vtgt2 . Specifically, the upper limit value applied to the target angular velocity Vtgt1 may be greater than the upper limit value applied to the target angular velocity _Vtgt2 , and the lower limit value applied to the target angular velocity _Vtgt1 may be smaller than the lower limit value applied to the target angular velocity _Vtgt2 . In other words, the range of values that the target angular velocity _Vtgt1 can take may be set to be wider than the range of values that the target angular velocity _Vtgt2 can take.

Note that while the target angular velocity has been described here as being changed in accordance with the control method selected by the control information generation unit 121, the control information may also be generated by changing the target angle in accordance with the control method.

Furthermore, although the case where the control information for controlling the second arm 23 is changed depending on the control method selected by the control information generator 121 has been described here, it is also possible to configure the control information for controlling another control target (for example, the first arm 22) to be changed depending on the selected method.

Furthermore, although the control method selected by the control information generation unit 121 has been described here as the control information generation method, the control method is not limited to the control information generation method.

Specifically, for example, a path (first transmission path) for transmitting a control signal including control information directly from the wireless device 10 to the second control-target wireless device 232 may be defined as the first control method, and a path (second transmission path) for transmitting the control signal from the wireless device 10 to the second control-target wireless device 232 via a relay device may be defined as the second control method. In this case, if there is degradation in wireless communication with the second control-target wireless device 232, it may be possible to ensure the quality of wireless communication by changing the transmission path of the control signal. In this case, the control method (transmission path) selected by the control information generator 121 is output (notified) from the control information generator 121 to the wireless unit 11, and the wireless unit 11 transmits the control information according to the selected transmission path.

Whether the first transmission path (second control method) or the second transmission path (second control method) is selected, it is sufficient that control information including a target control value (target angular velocity) is generated. However, for example, if the second transmission path is selected, the control information is transmitted via a relay device, and therefore, control information may be generated that takes into account the delay that occurs when transmitting via the relay device.

Note that, although it has been stated that when the second transmission path (second control method) is selected, the control signal is transmitted via a relay device, the relay device may also have that function, for example, the first control target wireless device 212.

Also, a method of transmitting a control signal at a control period T (first transmission period) may be referred to as the first control method, and a method of transmitting a control signal at a control period T' (second transmission period) may be referred to as the second control method. Note that T<T', where T' is, for example, 2T. This reduces the number of times a control signal is transmitted when wireless communication is degraded, thereby making it possible to suppress frequent retransmissions of the control signal and the impact that retransmissions of the control signal have on other controls (wireless communication). In this case, the control method (transmission period) selected by the control information generator 121 is output (notified) from the control information generator 121 to the wireless unit 11, and the wireless unit 11 transmits the control signal in accordance with the selected transmission period.

Furthermore, in this embodiment, a control signal generated by modulating control information is transmitted. A predetermined modulation rate (first modulation method) used to modulate the control information may be designated as the first control method, and a modulation rate (second modulation method) lower than the second control method may be designated as the second control method. A high modulation rate requires complex wireless communication, but if wireless communication deteriorates, the modulation rate can be lowered to enable stable wireless communication (i.e., improved noise resistance). In this case, the control method (modulation method) selected by the control information generation unit 121 is output (notified) from the control information generation unit 121 to the wireless unit 11, and the wireless unit 11 transmits a control signal in accordance with the selected modulation method.

In this embodiment, the control information generation unit 121 may select a control method for the control object (second arm 23) based on the degradation estimation result (whether or not there is degradation in wireless communication) output from the degradation estimation unit 122. The control method may be at least one of the above-mentioned control information generation method, the route for transmitting the control information to the control object, the period for transmitting the control information to the control object, and the modulation rate for modulating the control information, or a combination of these.

In this embodiment, a control method is selected (changed) when there is degradation in wireless communication, but it takes a predetermined time for the change in control method to be reflected in the control of the controlled object. If the time required for the change in control method to be reflected in the control of the controlled object is _td , it is preferable that m used in the degradation determination formula of the above-mentioned formula (1) be set to a value greater than the time _td (i.e., the period T×m). This makes it possible to avoid wireless communication from deteriorating before the change in control method is reflected in the control of the controlled object (i.e., the controlled object being controlled in a state where wireless communication is degraded).

When the processing of step S5 is executed, the control information generator 121 outputs the control information generated in step S5 to the radio unit 11.

Next, the radio unit 11 generates a control signal by modulating the control information output from the control information generator 121 and transmits the control signal to the second controlled radio device 232 (second arm 23) (step S6). Note that the generation and transmission of the control signal by the radio unit 11 may be performed in accordance with the control method (e.g., transmission path, transmission period, or modulation rate) selected by the control information generator 121 as described above.

The process shown in FIG. 3 above is executed, for example, every control cycle T. However, if the degradation estimation process is executed in step S4 to estimate that there is degradation in wireless communication and the control method is changed from the first control method to the second control method, control according to the second control method may continue even if the process shown in FIG. 3 (degradation estimation process) executed in the next control cycle estimates that there is no degradation in wireless communication. In this case, the second control method may be changed to the first control method if the degradation estimation process executed every control cycle T estimates that there is no degradation in wireless communication a predetermined number of times consecutively. However, a configuration in which the control method is selected based on the results of the degradation estimation process executed every control cycle T (i.e., the control method is changed every control cycle T) may also be used.

Note that while the flowchart shown in Figure 3 begins with the process of receiving the reception status, it may also start with another process. For example, it may start with the process of acquiring the target control value (the process of step S3), and then proceed in the order of steps S4, S5, S6, S1, and S2. Also, some steps may be omitted or performed multiple times within a certain control cycle. For example, if a status signal cannot be received within a certain control cycle, subsequent steps may be performed based on the status signal received immediately before. For example, if a status signal is received multiple times within a certain control cycle, the processing of each step may be performed based on the status signal received last.

Here, the description has been given assuming that the control object is the second arm 23. However, if the control object is the first arm 22, the degradation of the wireless communication used to control the first arm 22 (wireless communication with the first controlled wireless device 212) can be estimated, and a control method can be selected based on the estimation results. In other words, the process shown in Figure 3 above can be performed for each control object.

As described above, in this embodiment, a status signal containing status information indicating the status of the control object is received from the control object, a target control value for the control object is acquired, and a control signal containing control information for controlling the operation of the control object is transmitted in accordance with a control method for the control object selected based on the received status signal and the acquired target control value.

Specifically, in this embodiment, for example, the deterioration of wireless communication after a predetermined period (e.g., period T x m) has elapsed is estimated based on the wireless characteristics at time (n-1)T (first wireless characteristics measured from the first status signal) and the wireless characteristics at time nT (second wireless characteristics measured from the second status signal), as well as the target control value at time (n-1)T (first target control value acquired when the first status signal is received) and the target control value at time nT (second target control value acquired when the second status signal is received), and a control method for the control target is selected based on the estimation result.

In this embodiment, this configuration makes it possible to estimate in advance the degradation of wireless communication in the near future (i.e., after a period T x m has elapsed) from the transition of wireless characteristics from the past (time (n-1)T) to the present (time nT) (i.e., predict the degradation before the wireless communication actually deteriorates). Therefore, by changing the control method when degradation of the wireless communication (performance) is estimated, it is possible to prevent a significant deterioration in the quality of control of a control target using wireless communication (e.g., increased control delays).

The control method in this embodiment may be, for example, at least one of the control information generation method, the path for transmitting the control information, the period for transmitting the control information, and the modulation rate for modulating the control information. However, other methods other than those described in this embodiment may also be used as long as they can be changed to mitigate the impact of estimated wireless communication degradation on control of the control target. The control method applied to this embodiment (the control method selected by the control information generator 121) may be one that can appropriately respond to wireless communication degradation, for example, in accordance with the environment in which the wireless control system is operated.

Furthermore, in this embodiment, a configuration has been described in which a control signal is transmitted according to a control method selected in response to a degradation estimation result based on a status signal (radio characteristics measured from the status signal) and a target control value. However, the wireless device 10 may also be configured to estimate wireless communication degradation after a predetermined period has elapsed based on at least the status signal and the target control value. In other words, the wireless device 10 may be configured to contribute to suppressing a decline in the quality of control of a control target that uses wireless communication by estimating wireless communication degradation, and the degradation estimation result may also be used for purposes other than selecting a control method.

The following describes modified examples of the degradation estimation unit 122 described in this embodiment. Here, we will explain the first to third modified examples.

First, the first variant will be described. In the above-described embodiment, the degradation of wireless communication is estimated based on the wireless characteristics measured from the status signal and the target control value obtained from an external device. However, the first variant differs from this embodiment in that the degradation of wireless communication is estimated from the status information (the status of the control object indicated by) extracted from the status signal and the target control value obtained from an external device.

Here, the degradation estimation unit 122 in the first variant has an internal degradation estimation table. Note that the degradation estimation table may be stored, for example, in a memory unit internal to the processing unit 12 (degradation estimation unit 122), but may also be obtained from outside the processing unit 12 (or wireless device 10), for example.

Figure 5 shows an example of the data structure of a degradation estimation table. As shown in Figure 5, the degradation estimation table stores status information and the immediately preceding wireless characteristics corresponding to that status information. As described above, a status signal is transmitted from the control target to wireless device 10 every control period, and the immediately preceding wireless characteristics are the wireless characteristics measured from the status signal immediately preceding the status signal from which the status information associated with the immediately preceding wireless characteristics was extracted.

In the example shown in Figure 5, the degradation estimation table stores the previous wireless characteristic "100" in association with the status information "greater than or equal to 0 degrees and less than 1 degree." This indicates that the previous wireless characteristic was 100 when a status signal including status information indicating that the angle of the controlled object (e.g., second arm 23) is greater than or equal to 0 degrees and less than 1 degree was received.

The degradation estimation table also stores the previous wireless characteristic of "90" in association with the status information "1 degree or more and less than 2 degrees." This indicates that the previous wireless characteristic was 90 when a status signal was received that included status information indicating that the angle of the controlled object was 1 degree or more and less than 2 degrees.

Here, we have only explained the status information "0 degrees or more but less than 1 degree" and "1 degree or more but less than 2 degrees," but the degradation estimation table also stores the most recent wireless characteristics for each status information (i.e., the state of the controlled object).

The degradation estimation table may be prepared (created) in advance based on past status signals (past status information and past wireless characteristics) transmitted from the controlled object during actual operation of the wireless control system.

Next, we will explain the processing (deterioration estimation processing) of the deterioration estimation unit 122 in the first modified example. Here, we will explain the control object as the second arm 23 shown in Figure 1.

The deterioration estimation process in the first modified example is executed at time nT using the deterioration determination formula of the following formula (4).
Table[D(nT)+S(nT)×mT]<L _th formula (4)

In equation (4), Table[x] indicates the immediately preceding wireless characteristics when the state information (angle of the second arm 23) is x in the degradation estimation table (i.e., the immediately preceding wireless characteristics stored in the degradation estimation table in association with the state information "x"). Also, D(nT) indicates the state information (angle of the second arm 23) at time nT. S(nT) indicates the target angular velocity at time nT. Since m and _Lth are the same as those in equation (1) above, detailed explanations thereof will be omitted here.

Here, for example, assume that D(nT) is 1 degree, S(nT) is 100 (degree/sec), m is 3, and the control period T is 0.01 (sec). In this case, Table [D(nT) + S(nT) × mT] of the degradation determination formula (4) above becomes Table [4], and the degradation estimation unit 122 acquires the previous wireless characteristic "60" associated with the state information indicating an angle of 4 degrees (i.e., the state information "4 degrees or more and less than 5 degrees") from the degradation estimation table. Note that the previous wireless characteristic "60" acquired from the degradation estimation table in this manner corresponds to a predicted value (estimated value) of the wireless characteristic according to the state of the second arm 23 after the period T × 3 has elapsed. In this case, for example, if the degradation determination threshold L _th is 57, the degradation estimation unit 122 estimates that there is no degradation in the wireless communication.

On the other hand, if D(nT) is 2 degrees, S(nT) is 100 (degree/sec), m is 3, and the control period T is 0.01 (sec), the degradation determination formula Table [D(nT) + S(nT) × mT] becomes Table [5], and the degradation estimation unit 122 acquires the immediately preceding wireless characteristic "50" associated with the state information in which the angle is 5 degrees (i.e., the state information "5 degrees or more and less than 6 degrees") from the degradation estimation table. In this case, if the degradation determination threshold L _th is 57 as described above, the degradation estimation unit 122 estimates that there is degradation in the wireless communication.

As described above, in the first variant, radio characteristics corresponding to the state of the control object after the period T x m has elapsed are obtained from the degradation estimation table based on the state information D(nT) and target control value S(nT) extracted from the state signal, and degradation of wireless communication is estimated in advance based on the obtained radio characteristics.This makes it possible to select a control method that takes wireless communication degradation into account based on the estimation results, and transmit a control signal, thereby preventing a decline in the quality of control of the control object using wireless communication.

Note that while the degradation estimation table has been described here as holding the most recent wireless characteristics corresponding to the status information (the status of the control target indicated by the status information), the degradation estimation table may also hold the average value of the last N wireless characteristics instead of the most recent wireless characteristics, as shown in FIG. 6, for example. Note that the average value of the last N wireless characteristics is the average value of the wireless characteristics measured from each of the status signals from one before to the N before the status signal from which the status information associated with the average value of the last N wireless characteristics was extracted.

Here, for example, assume that the above-described degradation determination formula Table [D(nT)+S(nT)×mT] is Table [4]. In this case, if the degradation estimation table shown in Fig. 5 is referenced, it is estimated that there is no degradation in wireless communication when the degradation determination threshold _Lth is 57. On the other hand, if the degradation estimation table shown in Fig. 6 is referenced, the average value "55" of the wireless characteristics for the past N times is acquired from the degradation estimation table, and it is estimated that there is degradation in wireless communication.

The average value of the wireless characteristics for the past N times stored in the degradation estimation table shown in FIG. 6 may be an average value (weighted average value) obtained by weighting the wireless characteristics measured from each of the previous to N status signals. In this case, for example, weighting can be performed such that a greater weight is assigned to the wireless characteristics measured from a status signal received later than to the wireless characteristics measured from a status signal received earlier than that status signal. In other words, weighting can be performed according to the timing at which the wireless characteristics are measured, or other methods may be used.

In the first variant, it is sufficient if one of the degradation estimation tables shown in Figure 5 and Figure 6 is prepared in advance, but it is also possible to prepare both degradation estimation tables and select one of the degradation estimation tables to execute the degradation estimation process, for example, depending on the environment in which the wireless control system is operated (the operating environment of the controlled object) or instructions from the administrator of the wireless control system.

Furthermore, the deterioration determination formula (4) described in the first modified example is merely an example, and the deterioration estimation process may be performed using a different deterioration determination formula.

Furthermore, since the first variant is configured to estimate degradation of wireless communication using status information instead of the wireless characteristics used in the present embodiment described above, the wireless characteristic measurement unit 111 shown in Figure 2 may be omitted.

In addition, in the first variant, state information (fixed value) indicating the state of the control target immediately after power-on may be stored in a non-volatile memory or the like of the wireless device 10, and this state information may be used as an initial value when the degradation estimation process is executed.

Next, a second modified example will be described. Here, assuming that the control target is the second arm 23 shown in FIG. 1, it is conceivable that the wireless characteristics related to the wireless communication used to control the second arm 23 will change depending on the angle of the second arm 23 (i.e., the position of the second control target wireless device 232). However, the position of the second control target wireless device 232 will change not only depending on the angle of the second arm 23 (i.e., the rotation angle of the second motor 231), but also on the angle of the first arm 22 (i.e., the rotation angle of the first motor 211).

In the above-described embodiment, the degradation of wireless communication is estimated based on the status signal received from the second control-target radio device 232 and the target control value of the second arm 23. However, the second modified example differs from this embodiment in that the degradation of wireless communication is estimated based on the status signal received from the second control-target radio device 232 and the target control value of the first arm 22.

The degradation estimation process in the second modified example is performed using, for example, the degradation determination formula (1) described in the present embodiment above. However, while S(nT) and S((n-1)T) used to calculate ΔS in the degradation determination formula (1) are target control values for the second arm 23, S(nT) and S((n-1)T) in the second modified example are target control values for the first arm 22. Using this degradation determination formula, it is possible to estimate degradation of the wireless communication used to control the second arm 23 (i.e., wireless communication with the second controlled wireless device 232) based on the target control value of the first arm 22. The target control value of the first arm 22 may be obtained from an external device by the control information generator 121 and output to the degradation estimation unit 122.

Here, the degradation estimation process has been described as being performed using the degradation determination formula (1). However, in the second modified example, the degradation estimation process may also be performed using the degradation determination formula (4) described in the first modified example above. In this case, the degradation estimation process may be performed using D(nT) in the degradation determination formula (4) as status information indicating the state (angle) of the first arm 22. In other words, in the second modified example, the degradation of wireless communication may be estimated based on status information indicating the state of the second arm 23.

As described above, the second variant is configured to receive a status signal including status information indicating the status of the second arm 23 (first control object), acquire a target control value for the first arm 22 (second control object), and estimate wireless communication degradation in advance based on the status signal (wireless characteristics measured from the transmitted signal or status information extracted from the status signal) and the target control value. This allows a control method that takes wireless communication degradation into account based on the estimation results to be selected and a control signal to be transmitted, thereby preventing a decline in the quality of control of the control object using wireless communication.

For example, if the second arm 23 (second motor 231) is fixed, the deterioration estimation process can be performed based on the target control value of the first arm 22 as described above. However, since the position of the second control target radio device 232 also changes depending on the angle of the second arm 23, it is preferable that the deterioration of the wireless communication used to control the second arm 23 (i.e., the wireless communication with the second control target radio device 232) be estimated by further taking into account the target control value of the second arm 23.

In this case, the deterioration estimation unit 122 may operate to perform deterioration estimation processing based on, for example, a combination of the target control value of the first arm 22 and the target control value of the second arm 23.

Next, we will explain the third modified example. In the above-mentioned present embodiment, first modified example, and second modified example, the deterioration estimation process is performed using a deterioration determination formula. However, the third modified example differs from the present embodiment, first modified example, and second modified example in that the deterioration estimation process is performed using a learning model generated by applying various known machine learning algorithms, such as a neural network or random forest.

The learning model used in the third variant is generated by learning a data set that includes, for example, identification information that identifies the control object, wireless characteristics related to wireless communication used to control the control object or status information indicating the status of the control object, target control values for the control object or other control objects, and wireless characteristics (correct values) after a period T×m has elapsed.

This type of learning model allows the wireless characteristics after a period T×m to be predicted (output) by inputting the above-mentioned identification information, wireless characteristics or status information, and target control value, thereby enabling degradation estimation processing using the learning model. Specifically, when the learning model outputs wireless characteristics (predicted values), the wireless communication degradation can be estimated by comparing the wireless characteristics with the above-mentioned degradation threshold. Note that the learning model may also be configured to directly output a degradation estimation result indicating whether or not there is wireless communication degradation.

In the third variant described above, by continuing to train the learning model using data sets collected in accordance with the operation of the wireless control system, it may be possible to perform a more accurate deterioration estimation process.

Note that information (data) other than that described here may also be used as the dataset used to train the learning model.

As described above, according to this embodiment and the first to third modified examples, it is possible to estimate the deterioration of wireless communication before it is detected that the wireless communication has actually deteriorated (i.e., before the quality of the wireless communication actually deteriorates), thereby suppressing deterioration in the quality of control of controlled objects that use wireless communication.

In the above-described embodiment and the first to third modified examples, the control information generation unit 121 and the degradation estimation unit 122 have been described as separate functional units. However, for example, the degradation estimation unit 122 may be a functional unit included in the control information generation unit 121. Furthermore, instead of the control information generation unit 121 and the degradation estimation unit 122, a single functional unit having the functions of both the control information generation unit 121 and the degradation estimation unit 122 may be provided.

Furthermore, in the above-described embodiment and the first to third modified examples, the target control value has been described as being acquired (input) from an external device, but the target control value may also be generated internally in the wireless device 10 (control information generator 121) and managed within the wireless device 10.

Second Embodiment
Next, a second embodiment will be described. Note that a wireless control system including a wireless device according to this embodiment is similar to that of the first embodiment, and therefore will be described using FIG. 1 where appropriate.

Figure 7 is a block diagram showing an example of the configuration of a wireless device 10 according to this embodiment. In Figure 7, parts that are the same as those in Figure 2 described above are given the same reference numerals, and detailed description thereof will be omitted. The wireless device 10 according to this embodiment differs from the first embodiment described above in that the processing unit 12 includes a position calculation unit 123. Note that the position calculation unit 123, like the control information generation unit 121 and the degradation estimation unit 122, is realized, for example, by software, but may also be realized by hardware or a combination of software and hardware.

Based on status information indicating the status of the control object and the target control value of the control object, the position calculation unit 123 calculates the position of the control object indicated by the status information or target control value, or the position of the control object after a predetermined period has elapsed.

In this embodiment, the degradation estimation unit 122 estimates degradation of wireless communication based on the position of the control target calculated by the position calculation unit 123.

Next, an example of the processing procedure of the wireless device 10 will be described with reference to the flowchart in Figure 8.

Here, assuming that the control target is the second arm 23 shown in Figure 1, the wireless characteristics of the wireless communication used to control the second arm 23 change depending on the angle of the second arm 23 (i.e., the position of the second control target wireless device 232). Therefore, here we will explain the case where the position of the second control target wireless device 232 is used as the position of the control target to estimate the degradation of the wireless communication for controlling the second arm 23.

First, a control signal (a control signal for controlling the first arm 22) is transmitted from the wireless device 10 to the first controlled wireless device 212, the first motor 211 connected to the first controlled wireless device 212 rotates based on the control information extracted from the control signal, thereby controlling the angle of the first arm 22, and a status signal including status information indicating the state of the first arm 22 (i.e., a status signal generated by modulating the status information) is transmitted from the first controlled wireless device 212. Similarly, a control signal (a control signal for controlling the second arm 23) is transmitted from the wireless device 10 to the second controlled wireless device 232, the second motor 231 connected to the second controlled wireless device 232 rotates based on the control information extracted from the control signal, thereby controlling the angle of the second arm 23, and a status signal including status information indicating the state of the second arm 23 (i.e., a status signal generated by modulating the status information) is transmitted from the second controlled wireless device 232.

In this case, the radio unit 11 receives status signals transmitted from the first control-target radio device 212 and the second control-target radio device 232 (step S11). When the processing of step S11 is executed, the radio unit 11 demodulates the status signal received from the first control-target radio device 212 to extract status information (hereinafter referred to as status information of the first arm 22) from the status signal, and demodulates the status signal received from the second control-target radio device 232 to extract status information (hereinafter referred to as status information of the second arm 23) from the status signal. The radio unit 11 outputs the status information of the first arm 22 and the status information of the second arm 23 to the control information generator 121 and the position calculator 123.

Once step S11 is executed, step S12, which corresponds to step S2 shown in Figure 3, is executed.

Next, the control information generator 121 acquires the target control value of the first arm 22 and the target control value of the second arm 23 from an external device as external control information (step S13). The target control value of the first arm 22 and the target control value of the second arm 23 acquired in step S13 are output to the position calculator 123.

When the processing of step S13 is executed, the position calculation unit 123 calculates (predicts) the position of the second control target wireless device 232 after a predetermined period of time has elapsed based on the state information of the first arm 22 and the state information of the second arm 23 output from the wireless unit 11 and the target control value of the first arm 22 and the target control value of the second arm 23 output from the control information generation unit 121 (step S14).

The processing of step S14 (position calculation processing by the position calculation unit 123) will be described in detail below with reference to Figure 9. Figure 9 shows the positional relationship between the first motor 211, first control target wireless device 212, second motor 231, and second control target wireless device 232 when the SCARA robot 20 shown in Figure 1 is viewed from the Z-axis direction (top).

The rotation axis of the first motor 211 is set as the origin O on the X-Y plane on which the SCARA robot 20 is placed, and the distance between the first motor 211 and the second motor 231 and the distance between the second motor 231 and the second wireless device 232 to be controlled are assumed to be known (i.e., managed) by the wireless device 10. Furthermore, the position of the base 21 (first motor 211 and first wireless device 212 to be controlled) provided on the SCARA robot 20 is assumed to be fixed.

Here, the position (x, y) of the second controlled radio device 232 shown in FIG. 9 is expressed by the following equation (5).

In equation (5), _r1 represents the distance between the rotation axis of the first motor 211 and the rotation axis of the second motor 231, and _r2 represents the distance between the rotation axis of the second motor 231 and (the antenna of) the second controlled radio device 232. Also in equation (5), _θ1 represents the angle of the first arm 22 with respect to the X axis in response to the rotation of the first motor 211, and _θ2 represents the angle of the second arm 23 with respect to the vector ( _r1 cos( _θ1 ), _r1 sin( _θ1 )) in response to the rotation of the second motor 231. As described above, _r1 and _r2 are known values, and _θ1 and _θ2 can be obtained from the state information of the first arm 22 and the state information of the second arm 23.

On the other hand, for example, the angle θ ₁ ′ of the first arm 22 with respect to the X axis after the period T×m has elapsed can be expressed by the following equation (6).
θ ₁ ′=θ ₁ +S ₁ (nT)×mT Formula (6)

In equation (6), S ₁ (nT) is the target control value (target angular velocity) of the first arm 22 at time nT.

Furthermore, for example, the angle θ ₂ ′ of the second arm 23 with respect to the vector (r ₁ cos(θ ₁ ′), r ₁ sin(θ ₁ ′)) after the period T×m has elapsed can be expressed as in the following equation (7).
θ ₂ ′=θ ₂ +S ₂ (nT)×mT Formula (7)

In equation (7), S ₂ (nT) is the target control value (target angular velocity) of the second arm 23 at time nT.

The position calculation unit 123 calculates the position of the second controlled radio device 232 after the period T×m has elapsed using the following equation (8), which is obtained by applying the above equations (6) and (7) to equation (5).

The position calculation unit 123 outputs the position (predicted value) of the second control-target radio device 232 after the period T×m calculated as described above has elapsed to the degradation estimation unit 122. The position calculation unit 123 also outputs the position (current position) of the second control-target radio device 232 calculated using the above-described equation (5) to the degradation estimation unit 122.

Returning to FIG. 8, the degradation estimation unit 122 executes a process (degradation estimation process) to estimate degradation of the wireless communication used to control the second arm 23 (wireless communication with the second control target wireless device 232) based on the position of the second control target wireless device 232 after the period T×m has elapsed, as output from the position calculation unit 123 (step S15).

The degradation estimation process in this embodiment is performed by referring to a degradation estimation table (not shown) stored internally in the degradation estimation unit 122. Note that while the degradation estimation table referenced in the degradation estimation process of the second modification of the first embodiment stores status information (the status indicated by the status information) and radio characteristics corresponding to the status (e.g., the radio characteristics immediately before the status information) in association with each other, the degradation estimation table referenced in the degradation estimation process of this embodiment stores the position of the second control-target radio device 232 and the radio characteristics corresponding to the position in association with each other. The position of the second control-target radio device 232 stored in the degradation estimation table may be, for example, each of the divided ranges obtained by dividing the X-Y plane into a grid, or, as another example, a combination of a certain range of _θ1 and _θ2 .

Note that the wireless characteristics according to the location correspond to the wireless characteristics measured from the status signal received from the second controlled wireless device 232 located at that location.

According to this, by referring to the degradation estimation table, the degradation estimation unit 122 can acquire the radio characteristics (i.e., predicted values of the radio characteristics after the period T×m has elapsed) stored in the degradation estimation table in association with the position of the second controlled radio device 232 after the period T×m has elapsed, which is output from the position calculation unit 123. The degradation estimation unit 122 estimates that there is degradation in the radio communication when the radio characteristics acquired from the degradation estimation table are smaller than the degradation determination threshold L _th . On the other hand, the degradation estimation unit 122 estimates that there is no degradation in the radio communication when the radio characteristics acquired from the degradation estimation table are equal to or greater than the degradation determination threshold L _th .

The degradation estimation unit 122 inputs, for example, the current position of the second controlled wireless device 232 output from the position calculation unit 123 and the wireless characteristics (wireless characteristics corresponding to the current position) output from the wireless characteristic measurement unit 111, and associates the position and wireless characteristics with each other and registers them in the degradation estimation table (i.e., updates the degradation estimation table). In this way, in this embodiment, the degradation estimation table can be created while the wireless control system is in operation.

Furthermore, in a configuration in which a degradation estimation table is created while the wireless control system is in operation, there may be cases in which the wireless characteristics associated with the position of the second controlled wireless device 232 after the period T×m output from the position calculation unit 123 have elapsed are not stored in the degradation estimation table. In such cases, it may be assumed that there is no degradation in the wireless communication, or that there is degradation, or degradation estimation processing may be performed based on another method, such as that described in the first embodiment.

In this embodiment, the degradation estimation table referenced by the degradation estimation unit 122 may be prepared in advance, as in the second modified example of the first embodiment described above. If the degradation estimation table is prepared in advance, the radio characteristic measurement unit 111 included in the radio unit 11 may be omitted.

When step S15 is executed, steps S16 and S17, which correspond to steps S5 and S6 shown in Figure 3, are executed.

Here, the second arm 23 provided on the SCARA robot 20 shown in Figure 1 is the object to be controlled, so the description has been given assuming that degradation of wireless communication is estimated using the status information of the first arm 22 and the second arm 23 and the target control values of the first arm 22 and the second arm 23. However, depending on the configuration of the SCARA robot 20 or the object to be controlled, the status information and target control values used to estimate degradation of wireless communication may be changed as appropriate.

As described above, this embodiment has a degradation estimation table that stores the position of the control object and the wireless characteristics corresponding to that position in association with each other. The position of the control object after a predetermined period of time has elapsed is calculated based on the state of the control object indicated by the status information extracted from the status signal and the target control value of the control object, and the wireless characteristics corresponding to the calculated position are obtained from the degradation estimation table. In this embodiment, degradation of wireless communication is estimated based on the wireless characteristics obtained from the degradation estimation table in this way (i.e., the predicted values of the wireless characteristics after the predetermined period of time has elapsed).

In this embodiment, this configuration makes it possible to estimate the deterioration of wireless communication based on the position (predicted value) of the control target before detecting that the wireless communication has actually deteriorated, thereby suppressing deterioration in the quality of control using wireless communication.

In this embodiment, the position of the control target is described as being calculated by the position calculation unit 123, but the process of calculating the position may also be performed by the deterioration estimation unit 122.

In addition, in this embodiment, the deterioration estimation unit 122 and the position calculation unit 123 have been described as separate functional units, but, for example, the position calculation unit 123 may be a functional unit included in the deterioration estimation unit 122. Furthermore, instead of the deterioration estimation unit 122 and the position calculation unit 123, a single functional unit having the functions of both the deterioration estimation unit 122 and the position calculation unit 123 may be provided.

(Third embodiment)
Next, a third embodiment will be described. Note that a wireless control system including a wireless device according to this embodiment is similar to that of the first embodiment, and therefore will be described using FIG. 1 where appropriate.

Figure 10 is a block diagram showing an example of the configuration of a wireless device 10 according to this embodiment. In Figure 10, parts that are the same as those in Figure 2 described above are given the same reference numerals, and detailed description thereof will be omitted. The wireless device 10 according to this embodiment differs from the first embodiment described above in that the processing unit 12 includes a wireless environment estimation unit 124. Note that the wireless environment estimation unit 124, like the control information generation unit 121 and the degradation estimation unit 122, is realized, for example, by software, but may also be realized by hardware or a combination of software and hardware.

In this embodiment, the wireless control system is assumed to include an external sensor (hereinafter referred to as a wireless environment measurement sensor) that is placed, for example, outside the wireless device 10 and configured to measure information (hereinafter referred to as wireless environment information) related to the wireless communication propagation environment (hereinafter referred to as the wireless environment).

The radio environment estimation unit 124 acquires radio environment information measured by the radio environment measurement sensor described above as external information. The radio environment estimation unit 124 estimates the degradation of wireless communication based on the radio environment indicated by the acquired radio environment information.

In this embodiment, a control method for the control object is selected based on the estimation results by the degradation estimation unit 122 and the estimation results by the radio environment estimation unit 124, and a control signal is transmitted in accordance with that control method.

Next, an example of the processing procedure of the wireless device 10 will be described with reference to the flowchart in Figure 11.

First, steps S21 to S23, which correspond to steps S1 to S3 shown in Figure 2, are executed.

Next, the deterioration estimation unit 122 executes a first deterioration estimation process (step S24). Note that the first deterioration estimation process executed in step S24 is similar to the deterioration estimation process executed in step S4 shown in FIG. 2, and therefore a detailed description thereof will be omitted here.

When the processing of step S24 is executed, the radio environment estimation unit 124 acquires radio environment information measured by the radio environment measurement sensor from the radio environment measurement sensor (step S25).

When the processing of step S25 is executed, the radio environment estimation unit 124 executes a second degradation estimation process based on the radio environment information acquired in step S25 (step S26).

Here, we will briefly explain an example of the second deterioration estimation process. Here, we assume that a camera (imaging device) capable of capturing images of the periphery of the wireless device 10 and the control target (e.g., the second arm 23) is used as the wireless environment measurement sensor. In this case, the wireless environment estimation unit 124 acquires, as wireless environment information, images including the periphery (environment) of the wireless device 10 and the control target.

In this case, the wireless environment estimation unit 124 determines the propagation environment (wireless environment) of the wireless communication used to control the control object based on the acquired video, and estimates the degradation of the wireless environment.

Specifically, the wireless environment estimation unit 124 analyzes the acquired video and determines that, for example, an object (obstacle) has come between the wireless device 10 and the control target, causing wireless communication with poor visibility (non-line-of-sight communication) to be performed (i.e., a wireless environment with good visibility changes to a wireless environment with poor visibility), and estimates that the wireless environment has deteriorated. On the other hand, the wireless environment estimation unit 124 analyzes the acquired video and determines that wireless communication with good visibility (line-of-sight communication) will continue to be performed, and estimates that the wireless environment has not deteriorated.

When the processing of step S26 is executed, the radio environment estimation unit 124 outputs the result of the processing of step S26 (i.e., the estimation result of whether or not there is degradation in the radio environment) to the control information generation unit 121.

Next, the control information generation unit 121 selects a control method for the control object based on the estimation result output from the degradation estimation unit 122 (hereinafter referred to as the first degradation estimation result) and the estimation result output from the radio environment estimation unit 124 (hereinafter referred to as the second degradation estimation result), and generates a control signal in accordance with the selected control method (step S27).

Assuming that the first and second control methods described in the first embodiment above are prepared (set) in advance, for example, if the degradation estimation unit 122 outputs a first degradation estimation result indicating that there is no degradation in wireless communication and the wireless environment estimation unit 124 outputs a second degradation estimation result indicating that there is no degradation in the wireless environment, the first control method is selected. On the other hand, if the degradation estimation unit 122 outputs a first degradation estimation result indicating that there is degradation in wireless communication, or the wireless environment estimation unit 124 outputs a second degradation estimation result indicating that there is no degradation in the wireless environment, the second control method is selected.

Note that the third control method may be selected when the second degradation estimation result indicating that the wireless environment is degraded is output from the wireless environment estimation unit 124, and the second control method may be selected when the second degradation estimation result indicating that the wireless environment is not degraded is output from the wireless environment estimation unit 124 and the first degradation estimation result indicating that the wireless communication is degraded is output from the degradation estimation unit 122. The third control method may be, for example, a method of generating control information including the target angular velocity V _tgt1 ×β as the target angular velocity V _tgt3 , where 0≦β<α<1.

Note that the processing performed by the control information generator 121 after the control method has been selected is the same as that described in the first embodiment, and therefore will not be described in detail here.

Once step S27 is executed, step S28, which corresponds to step S6 shown in Figure 3, is executed.

Note that in the example shown in Figure 11, for convenience, the second deterioration estimation process is described as being executed after the first deterioration estimation process, but the order in which the first and second deterioration estimation processes are executed may be changed.

As described above, in this embodiment, radio environment information regarding the radio environment (radio communication propagation environment) is acquired, and the control method for the control object is selected based on the acquired radio environment information in addition to the status signal and target control value described in the first embodiment.

In this embodiment, this configuration makes it possible to estimate the deterioration of wireless communication by taking into account the wireless environment before detecting that the wireless communication has actually deteriorated, thereby suppressing any deterioration in the quality of control of controlled objects that use wireless communication.

In this embodiment, the control information generation unit 121 and the radio environment estimation unit 124 have been described as separate functional units, but, for example, the radio environment estimation unit 124 may be a functional unit included in the control information generation unit 121. Furthermore, instead of the control information generation unit 121 and the radio environment estimation unit 124, a single functional unit having the functions of both the control information generation unit 121 and the radio environment estimation unit 124 may be provided.

Furthermore, in this embodiment, a configuration in which a radio environment estimation unit 124 is added to the wireless device 10 according to the first embodiment has been described, but this embodiment may also be applied to the second embodiment described above. In other words, the wireless device 10 (processing unit 12) according to this embodiment may be configured to include the position calculation unit 123 described in the second embodiment described above.

At least one of the embodiments described above can provide a wireless device, system, method, and program that can suppress degradation in the quality of control over a control target using wireless communication.

While several embodiments of the present invention have been described, these embodiments are presented as examples and are not intended to limit the scope of the invention. These embodiments can be implemented in a variety of other forms, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. These embodiments and their variations are within the scope of the invention and its equivalents as defined in the claims, as well as the scope and spirit of the invention.

10...wireless device, 11...wireless unit, 12...processing unit, 20...scalar robot, 21...base, 22...first arm, 23...second arm, 24...gripper, 111...wireless characteristic measurement unit, 121...control information generation unit, 122...deterioration estimation unit, 123...position calculation unit, 124...wireless environment estimation unit, 211...first motor, 212...first wireless device to be controlled, 231...second motor, 232...second wireless device to be controlled.

Claims (11)

In a wireless device that controls a control target using wireless communication,
receiving means for receiving a status signal including status information indicating a status of the controlled object;
a first acquisition means for acquiring a target control value of the control object;
an estimation means for estimating a deterioration of the wireless communication after a predetermined period of time has elapsed based on the received status signal and the acquired target control value;
a transmitting means for transmitting a control signal including control information for controlling an operation of the controlled object in accordance with a control method for the controlled object selected based on the estimation result ;
Measurement means and
Equipped with
the state signal includes a first state signal including first state information and a second state signal including second state information indicating a state of the control object transitioned from the state of the control object indicated by the first state information,
the target control value includes a first target control value acquired when the first status signal is received and a second target control value acquired when the second status signal is received;
the measuring means measures a first radio characteristic related to the wireless communication from the received first status signal, and measures a second radio characteristic related to the wireless communication from the received second status signal;
The estimation means estimates wireless characteristics after a predetermined period has elapsed based on the measured first and second wireless characteristics and the acquired first and second target control values, and estimates that there is degradation in the wireless communication when the estimated wireless characteristics are smaller than a threshold value.
Radio equipment. In a wireless device that controls a control target using wireless communication,
receiving means for receiving a status signal including status information indicating a status of the controlled object;
a first acquisition means for acquiring a target control value of the control object;
an estimation means for estimating a deterioration of the wireless communication after a predetermined period of time has elapsed based on the received status signal and the acquired target control value;
a transmitting means for transmitting a control signal including control information for controlling an operation of the controlled object in accordance with a control method for the controlled object selected based on the estimation result;
a storage means for storing in advance the past states of the control target and the radio characteristics corresponding to the states in association with each other;
Equipped with
The estimation means acquires, from the storage means, wireless characteristics corresponding to the state of the control object after a predetermined period has elapsed, based on the state information extracted from the received state signal and the acquired target control value, and estimates that there is degradation of the wireless communication when the acquired wireless characteristics are smaller than a threshold value.
Radio equipment. the controlled objects include a first controlled object and a second controlled object;
the receiving means receives a status signal including status information indicating a status of the first control object,
the first acquisition means acquires a target control value of the second control object;
The wireless device according to claim 1 or 2, wherein the transmitting means transmits a control signal including control information for controlling an operation of the first control object in accordance with a control method for the first control object selected based on the estimated result. In a wireless device that controls a control target using wireless communication,
receiving means for receiving a status signal including status information indicating a status of the controlled object;
a first acquisition means for acquiring a target control value of the control object;
an estimation means for estimating a deterioration of the wireless communication after a predetermined period of time has elapsed based on the received status signal and the acquired target control value;
a transmitting means for transmitting a control signal including control information for controlling an operation of the controlled object in accordance with a control method for the controlled object selected based on the estimation result;
Equipped with
the estimation means estimates that there is degradation in the wireless communication when the wireless characteristics measured from the status signal or the wireless characteristics predicted by a learning model to which the status information extracted from the status signal and the acquired target control value are input are smaller than a threshold value ;
A wireless device, wherein the learning model is generated by learning a data set including wireless characteristics related to wireless communication used to control the controlled object or status information indicating the status of the controlled object, a target control value of the controlled object, and wireless characteristics after a predetermined period has elapsed . In a wireless device that controls a control target using wireless communication,
receiving means for receiving a status signal including status information indicating a status of the controlled object;
a first acquisition means for acquiring a target control value of the control object;
an estimation means for estimating a deterioration of the wireless communication after a predetermined period of time has elapsed based on the received status signal and the acquired target control value;
a transmitting means for transmitting a control signal including control information for controlling an operation of the controlled object in accordance with a control method for the controlled object selected based on the estimation result;
a storage means for storing the position of the control object and a wireless characteristic corresponding to the position in association with each other;
a calculation means for calculating a position of the controlled object after a predetermined period has elapsed, based on the state of the controlled object indicated by the state information extracted from the received state signal and the acquired target control value;
Equipped with
The estimation means acquires the wireless characteristics corresponding to the calculated position from the storage means, and if the acquired wireless characteristics are smaller than a threshold, estimates that the wireless communication has deteriorated.
Radio equipment. The wireless device according to any one of claims 1 to 5, wherein the control method includes at least one of a method for generating the control information, a path for transmitting the control information, a period for transmitting the control information , and a modulation rate for modulating the control information. A wireless device according to any one of claims 1 to 6 ;
A system comprising the control object and The system according to claim 7, wherein the object to be controlled includes a robot having a motor that operates based on control information for controlling the operation of the object to be controlled and a movable part that moves due to the rotation of the motor, and at least one of the motor and the movable part . 9. The system according to claim 7 , further comprising a sensor for measuring radio environment information relating to a propagation environment of the wireless communication. A method executed by a wireless device that controls a control target using wireless communication,
receiving a status signal including status information indicating a status of the controlled object;
obtaining a target control value of the control object;
estimating a deterioration of the wireless communication after a predetermined period of time has elapsed based on the received status signal and the acquired target control value;
and transmitting a control signal including control information for controlling an operation of the controlled object in accordance with a control method for the controlled object selected based on the estimated result ;
the state signal includes a first state signal including first state information and a second state signal including second state information indicating a state of the control object transitioned from the state of the control object indicated by the first state information,
the target control value includes a first target control value acquired when the first status signal is received and a second target control value acquired when the second status signal is received;
measuring a first radio characteristic related to the wireless communication from the received first status signal and measuring a second radio characteristic related to the wireless communication from the received second status signal;
The estimating step includes a step of estimating wireless characteristics after a predetermined period has elapsed based on the measured first and second wireless characteristics and the acquired first and second target control values, and estimating that there is degradation in the wireless communication when the estimated wireless characteristics are smaller than a threshold value.
method. A program executed by a computer of a wireless device that controls a control target using wireless communication,
The computer,
receiving a status signal including status information indicating a status of the controlled object;
obtaining a target control value of the control object;
estimating a deterioration of the wireless communication after a predetermined period of time has elapsed based on the received status signal and the acquired target control value;
transmitting a control signal including control information for controlling the operation of the controlled object in accordance with a control method for the controlled object selected based on the estimation result ;
the state signal includes a first state signal including first state information and a second state signal including second state information indicating a state of the control object transitioned from the state of the control object indicated by the first state information,
the target control value includes a first target control value acquired when the first status signal is received and a second target control value acquired when the second status signal is received;
causing the computer to further perform the steps of measuring a first radio characteristic related to the wireless communication from the received first status signal and measuring a second radio characteristic related to the wireless communication from the received second status signal;
The estimating step includes a step of estimating wireless characteristics after a predetermined period has elapsed based on the measured first and second wireless characteristics and the acquired first and second target control values, and estimating that there is degradation in the wireless communication when the estimated wireless characteristics are smaller than a threshold value.
program.