JP7706893B2 - ROBOT SYSTEM, METHOD FOR CONTROLLING ROBOT SYSTEM, PRODUCTION OF ARTICLE USING ROBOT SYSTEM, ROBOT HAND, METHOD FOR CONTROLLING ROBOT HAND, CONTROL PROGRAM, AND RECORDING MEDIUM - Google Patents

Description

The present invention relates to a robot system.

In recent years, there has been an increasing demand to automate the manufacturing process of industrial products such as cameras and printers, which was previously performed manually, using robotic devices with robotic hands and robotic arms. Many of the parts (workpieces) that make up these products are small and precise, and come in a wide variety of shapes and materials. For this reason, it is necessary to set a gripping posture suitable for the workpiece so that the robotic hand can correctly grip it. One of the above-mentioned methods is the technology described in Patent Document 1. Patent Document 1 below discloses a technology in which a camera is installed on the fingertip, the camera on the fingertip is used to measure the distance to the workpiece, and a gripping posture suitable for the workpiece is set.

JP 2009-66678 A

However, the technology described in Patent Document 1 requires image processing to measure the position and orientation of the workpiece using a camera. When performing image processing, various adjustments (adjusting the orientation of the lighting, calibrating the camera, adjusting image processing parameters, etc.) are required, which makes it difficult to easily set the gripping orientation, which is an issue.

In view of the above, the present invention aims to provide a robot system that can easily set the gripping posture.

In order to solve the above problems, the present invention employs a robot system including a robot hand having finger portions and a palm portion on which the finger portions are provided , a control device, a first sensor that acquires information regarding the distance between an object and the finger portions, and a second sensor that is provided at a predetermined position on the palm portion and acquires information regarding the distance to the object, wherein the control device controls the position and/or posture of the robot hand so that the finger portions are aligned with the object based on the detection result of the first sensor during a grasping operation in which the finger portions are moved toward the object to grasp the object by operating the finger portions, and controls the position and/or posture of the robot hand so that the palm portions are aligned with the object based on the detection result of the second sensor during a grasping operation in which the finger portions are moved toward the object to grasp the object by operating the finger portions.

The present invention makes it easy to set the gripping position.

FIG. 1 is an explanatory diagram showing a schematic configuration of a robot system in which the present invention can be adopted. FIG. 1 is an explanatory diagram showing a system configuration of a sensor to which the present invention can be applied. 1 is an explanatory diagram showing a schematic configuration of an end effector to which the present invention can be applied; FIG. 1 is a flowchart showing a processing procedure of a robot system in which the present invention can be adopted. FIG. 11 is a flowchart showing a process for acquiring sensor data to which the present invention can be applied. FIG. 11 is a flowchart showing a process procedure for calculating a command value to which the present invention can be applied. FIG. 1 is a transition diagram of processing related to a robot system in which the present invention can be adopted. FIG. 11 is an explanatory diagram showing an outline of a sensor according to a second embodiment of the present invention. FIG. 11 is an explanatory diagram showing an outline of a workpiece according to a third embodiment of the present invention. FIG. 11 is an explanatory diagram showing a schematic configuration of an end effector according to a third embodiment of the present invention. FIG. 11 is a transition diagram of processing related to a robot system according to a third embodiment of the present invention.

Below, preferred embodiments for carrying out the present invention will be described in detail with reference to the attached drawings. Note that the examples shown below are merely examples, and for example, the detailed configurations can be changed without departing from the spirit of the present invention. Also, the numerical values given in each embodiment are for reference only and do not limit the present invention.

(First embodiment)
1 is an explanatory diagram showing a schematic configuration of a robot system in which the present invention can be adopted. The robot system 100 of this embodiment is composed of a robot arm body 200, a robot hand body 300, a sensor node 800, a robot hand controller 500, a robot arm controller 400, a sensor controller 700, and an external input device 900. A workpiece W1, which is an object to be grasped, is placed on a placement table S1.

By using the robot system 100 to manipulate the workpiece W1 and assemble it to another workpiece, an industrial product or article can be manufactured. For example, the operation on the workpiece W1 is performed by using the robot arm body 200 and the robot hand body 300 to grasp and move the workpiece W1 as an object to be grasped, and further by fitting or assembling the workpiece W1 to the other workpiece.

In this embodiment, the robot arm body 200 is a multi-joint robot arm, and the base of the robot arm body 200 is fixed to a base 600. A robot hand body 300, which is an end effector, is attached to the tip of the robot arm body 200. The robot hand body 300 is also equipped with a sensor node 800. This robot hand body 300 is used to perform operations on a workpiece W1. Each joint of the robot arm body 200 is provided with a motor as a drive source for driving each of these joints, and an encoder as a position detection means for detecting the rotation angle of the motor. The installation position and output method of the encoder are not important.

The robot hand body 300 is a hand with at least one degree of freedom that opens and closes two fingers using a motor and an opening/closing mechanism described below to grasp or release the workpiece W1, and it is sufficient if the robot hand can grasp the workpiece W1 without displacing it relative to the robot arm body 200. Note that, although the number of fingers is two in this embodiment, this can be changed as appropriate by those skilled in the art. Also, in this embodiment, the fingers of the robot hand 300 are driven by a motor (not shown), but an air gripper such as one driven by air pressure may also be used.

The robot arm control device 400 has a CPU (Central Processing Unit) 401, a ROM (Read Only Memory) 402, and a RAM (Random Access Memory) 403. It also has an arm IF (Inter Face) 404, which handles communication with the outside, an external IF 405, and a flash ROM 406. The ROM 402 or the flash ROM 406 stores programs for controlling the corresponding drive units in response to various operations of the robot arm main body 200, as well as data required for such control. The RAM 403 functions as a working area for the CPU 401.

The arm IF 404 functions as an interface for communicating with the robot arm body. The external IF 405 functions as an interface for communicating with the robot hand control device 500, the sensor control device 700, and the external input device 900. The CPU 401 calculates the angle that each joint should take with respect to the target position and posture of the tip of the robot arm body 200, which is the destination of the robot hand body 300. Then, via the arm IF 404, it outputs a command value to a servo circuit (not shown) that controls the motor of each joint, and drives and controls each joint of the robot arm body 200. This allows the workpiece W1 held by the robot hand body 300 to be transported to the target position.

Like the robot arm control device 400, the robot hand control device 500 also has a CPU 501, ROM 502, RAM 503, hand IF 504, external IF 505, and flash ROM 506. The ROM 502 or flash ROM 506 stores programs for controlling the corresponding drive units in response to various operations of the robot hand main body 300, as well as data necessary for such control. The RAM 503 functions as a working area for the CPU 501.

The hand IF 504 functions as an interface for communicating with the robot hand body 300. The external IF 505 functions as an interface for communicating with the robot arm control device 400, the sensor control device 700, and the external input device 900. The CPU 501 calculates the angle that the drive source should take with respect to the target position of the fingers of the robot hand body 300. Then, a command value is output via the hand IF 504 to a servo circuit (not shown) that controls the drive source, and the fingers of the robot hand body 300 are driven and controlled. This allows the robot hand body 300 to grasp the workpiece W1.

Figure 2 is a control block diagram showing the control configuration of the sensor system of this embodiment. The sensor system of this embodiment is composed of sensors 811 to 816, a sensor node 800, and a sensor control device 700 that controls the sensors 811 to 816.

Sensors 811-816 are distance sensors capable of measuring the distance to the workpiece W1. Sensors 811-816 may be proximity sensors or TOF (Time Of Flight) sensors, but in this embodiment they are proximity sensors. The proximity sensor is a photoreflector consisting of an LED (not shown) and a phototransistor (not shown). An infrared LED is preferable for the LED that is the transmitter. The light emitted from the transmitter is reflected by the workpiece W1, and the reflected light is received by the phototransistor in the receiver, thereby measuring the distance. The phototransistor outputs the brightness of the reflected light according to the distance as a current. The current can be measured as a voltage by passing it through a resistor.

The sensor node 800 has a power supply controller 801 and a sensor data acquisition unit 802. The power supply controller 801 can control the on/off of the power supplies of the sensors 811-816. The sensor data acquisition unit 802 can acquire the output (detection results) of the sensors 811-816. In this embodiment, the sensors 811-816 are proximity sensors, so the sensor output is a voltage, and the sensor data acquisition unit 802 is equivalent to an AD converter. In addition, the power supply controller 801 and the sensor data acquisition unit 802 are provided with a node IF 804 capable of serial communication in order to communicate with the sensor control device 700.

The sensor control device 700 has a CPU 701, a ROM 702, a RAM 703, a sensor IF 704, an external IF 705, and a flash ROM 706. The ROM 702 or the flash ROM 706 stores programs for controlling the power supply of the sensors 811-816 and acquiring and correcting sensor data, as well as data necessary for such control. The RAM 703 functions as a working area for the CPU 701. The sensor IF 704 functions as an interface connected to the node IF 804 for communicating with the power supply controller 801 and the sensor data acquisition unit 802 in the sensor node 800. The external IF 705 functions as an interface for communicating with the robot arm control device 400, the robot hand control device 500, etc.

Figure 3 is a diagram showing the schematic configuration of the robot hand body 300 of this embodiment. The robot hand body 300 has a hand motor driver 301, an encoder 302, a hand motor 303, a gear 304, finger portions 305 and 306, and slide guides 307 and 308.

The hand motor driver 301 measures the rotation angle of the hand motor 303 with an encoder 302 and performs feedback control based on command values from each control device. Then, the positions of the fingers 305 and 306 can be controlled via the gear 304 and slide guides 307 and 308.

Sensors 811, 812, 813, and 814 are arranged at the tip of the finger portion 305 at the positions shown in the figure. The sensors 811, 812, and 813 are arranged in the same plane within a range smaller than the thickness of the workpiece W1 in the Z-axis direction, and can measure the distance between the finger portion 305 and the gripping direction (X-axis direction) of the workpiece W1. The sensor 814 is also arranged so that it can measure the distance between the finger portion 305 and the hand tip direction (Z-axis direction) of the base 600 or the mounting table S1. The tip of the finger portion 305 is also provided with a contact portion 309 that serves as a surface that comes into contact with the workpiece W1. The contact portion 309 is provided so that it is a surface different from the surface on which the sensors 811 to 813 are provided (a step having a predetermined height from the surface on which each sensor is provided). This reduces the risk of contact between the workpiece W1 and each sensor when gripping the workpiece W1, and reduces the possibility of the sensor breaking down.

On the other hand, sensors 815 and 816 are arranged at an angle on the palm of the robot hand body 300 so that they are positioned relative to the workpiece W1 at a length greater than the width of the workpiece W1 in the Y-axis direction (the direction perpendicular to the gripping direction of the fingers). The above-mentioned arrangement makes it possible for each sensor to reliably measure the surface of the workpiece.

Next, the processing procedure in the robot system 100 of this embodiment will be explained using the flowchart shown in Figure 4. As a premise, the workpiece W1 is assumed to be a rectangular parallelepiped, roughly placed on the mounting table S1 at a predetermined angle with respect to the robot hand body 300. Also, the workpiece W1 starts from a position where it can be grasped by the fingers 305, 306 of the robot hand body 300. By measuring the workpiece W1 or the mounting table S1 using sensors 811-816, the position and orientation of the robot hand body 300 is appropriately changed to grasp the workpiece. Also, the flow described below is assumed to be executed by the CPUs of each control device communicating with each other.

First, in step S10, the target values of the fingers 305 and 306 are set. The target values are the width D _ref immediately before gripping, the clearance h _ref with the mounting table S1, the positioning tolerance ε _xyz , and the attitude tolerance ε _Txyz . These values determine the target gripping attitude of the robot hand body 300. In this embodiment, by setting these values, the robot hand body 300 targets a gripping attitude along the workpiece W1 (where the contact surface of each finger is approximately parallel to the surface of the workpiece W1 it contacts, and the surface of the palm is approximately parallel to the surface of the workpiece W1 facing the palm). The positioning tolerance ε _xyz is the tolerance of the distance between each finger and palm measured by the sensor and the workpiece, and the attitude tolerance ε _Txyz is the tolerance of the relative angle between the fingers and palm and the workpiece that is geometrically determined from the measurement results of the sensor.

Next, in step S20, the sensor control device 700 acquires sensor data from the sensors 811 to 816. Details will be described later with reference to FIG. 5.

Next, in step S30, the sensor control device 700 acquires the current values of the position and orientation of the robot hand main body 300. Information on the position and orientation of the robot hand main body 300, i.e., x, y, z, _Tx , Ty, _Tz , and the grip width H, which is the relative positional relationship between the fingers 305, 307, is acquired from the _robot arm control device 400 and the robot hand control device 500 via the external IF 705.

Next, in step S40, the control completion condition is compared. The control completion condition is when each measurement value D satisfies the following formula:

The subscript numbers of each measurement value D indicate which of the sensors 811 to 816 acquired the sensor data for which the distance measurement value relates. _D1 is the measurement value of sensor 811, _D2 is the measurement value of sensor 812, _D3 is the measurement value of sensor 813, _D4 is the measurement value of sensor 814, _D5 is the measurement value of sensor 815, and _D6 is the measurement value of sensor 816. α is the angle that sensor 815 makes with the palm of the robot hand body 300. _L7a is the length between the measurement points of sensors 811 and 813, _L7c is the length between the measurement points of sensors 815 and 816, and _L7g is the length between the measurement points of sensors 811 and 812. If the control completion condition is satisfied, the process is completed.

Conversely, if the target value does not satisfy the control completion condition, step S40: No, proceed to step S50. In step S50, the sensor control device 700 calculates the command value to be sent to the robot arm control device 400 and the robot hand control device 500. Details will be described later with reference to FIG. 6.

Next, in step S60, the calculated command values are sent to the robot arm control device 400 and the robot hand control device 500 via the external IF 705. Then, the process returns to just before step S20, where the sensor data is acquired again and it is determined whether the measured value satisfies the control completion condition shown in formula (1).

In step S40, if each measurement value meets the control completion condition, it is determined that the robot hand body 300 is in an appropriate gripping posture, and the control flow for adjusting the gripping posture is terminated.

Next, step S20, which acquires sensor data, will be described in detail. FIG. 5 is a flowchart showing the processing procedure (step S20) for acquiring sensor data in this embodiment.

First, in step S21, the variable i is set to 1. The variable i indicates the sensor number. The sensor number corresponds to the sensor with the subscript number of each measurement value D.

Next, in step S22, it is determined whether the variable i exceeds the total number of sensors N. In this embodiment, N is 6. If the variable i does not exceed the total number of sensors N, step S22: No and the process proceeds to step S23.

In step S23, one of sensors 811 to 816 is turned ON using the power supply controller 801 according to the value of variable i. For example, if variable i is 1, only sensor 811 is turned ON, and if variable i is 6, only sensor 816 is turned ON.

Next, in step S24, the sensor data acquisition unit 802 is used to acquire sensor data from any of the ON sensors 811-816. In this embodiment, the sensors 811-816 are proximity sensors, so the sensor data is voltage. Also, the sensor data may be acquired multiple times and filtered.

Then, in step S25, the power supply controller 801 turns off all of the sensors 811 to 816.

Then, in step S26, the variable i is incremented and the process returns to the state immediately before step S22. The above flow is repeated to obtain sensor data from the required number of sensors.

In step S22, if the variable i exceeds the total number of sensors N, step S22: Yes is selected and the process proceeds to step S27. In step S27, the sensor data is corrected to distance measurement data. In the case of a proximity sensor, the voltage decreases as the distance to the measurement object increases after the focal length of the proximity sensor, so a table or polynomial can be used to correct the voltage to distance. In this case, it is preferable to obtain the coefficient values of the table or polynomial in advance and store them in flash ROM 706. In this way, the influence of the LED light of other sensors can be reduced and the measurement accuracy of the sensor can be improved. The sensor data is obtained as described above, and the control flow for obtaining sensor data ends.

Next, the control flow for calculating the command values to adjust the position and orientation of the robot hand body 300 will be described in detail. FIG. 6 is a flowchart showing the details of the processing procedure (steps S30 to S60) relating to the command value calculation and position and orientation adjustment in this embodiment. FIG. 7 is a state diagram of the robot hand body 300 in the control flowchart of FIG. 6. Here, as shown in FIG. 7(a), the workpiece W1 starts in a state inclined at a predetermined angle relative to the robot hand body 300.

As shown in Figure 6, first in step S71, the completion conditions for the X- and Y-axis postures are compared. The completion conditions are that all of the following expressions are satisfied (Figure 7 (a) to (d)).

From Fig. 7(a), it is determined whether the detection values from sensors 811 and 813 satisfy formula (2), and if they do not, the process proceeds to step S75, a command value for correcting the posture around the Y axis is output, and the process returns to just before step S71 to change the posture of the robot hand main body 300. If the detection values from sensors 811 and 813 satisfy formula (2), the posture around the Y axis becomes the state shown in Fig. 7(b), and adjustment of the posture of the robot hand main body 300 around the Y axis is completed.

Similarly, from FIG. 7(c), it is determined whether the detection values from sensors 815 and 816 satisfy formula (2), and if they do not, the process proceeds to step S75, a command value for correcting the posture around the X axis is output, and the process returns to just before step S71 to change the posture of the robot hand main body 300. If the detection values from sensors 815 and 816 satisfy formula (2), the posture around the X axis becomes the state shown in FIG. 7(d), and adjustment of the posture of the robot hand main body 300 about the X axis is completed.

In step S75, the command values for posture correction around the X and Y axes are calculated using the following formula:

When adjustment of the posture around the X-axis and the posture around the Y-axis is completed in step S71, proceed to step S72. In step S72, a comparison is made with the completion conditions for the Z-axis position (Figure 7 (e) (f)).

From Fig. 7(e), it is determined whether the detection value from the sensor 814 satisfies formula (4), and if it does not, the process proceeds to step S76, a command value for correcting the Z-axis position is output, and the process returns to just before step S72 to change the posture of the robot hand body 300. If the detection value from the sensor 814 satisfies formula (4), the state becomes as shown in Fig. 7(f), and adjustment of the Z-axis position of the robot hand body 300 is completed.

In step S76, the command value for Z-axis position correction is calculated using the following formula:

When the adjustment of the Z-axis position is completed in step S72, proceed to step S73. In step S73, the posture around the Z-axis is compared with the completion conditions (Figure 7 (g) (h)).

From Fig. 7(g), it is determined whether the detection values from sensors 811 and 812 satisfy formula (6), and if they do not, the process proceeds to step S77, a command value for correcting the posture around the Z axis is output, and the process returns to just before step S73 to change the posture of the robot hand main body 300. If the detection values from sensors 811 and 812 satisfy formula (6), the state becomes as shown in Fig. 7(h), and the adjustment of the posture of the robot hand main body 300 around the Z axis is completed.

In step S77, the command value for posture correction around the Z axis is calculated using the following formula:

When adjustment of the posture around the Z axis is completed in step S73, proceed to step S74. In step S74, the completion conditions for the X-axis position and Y-axis position are compared (Figure 7 (i) (j)).

From FIG. 7(i), it is determined whether the detection values from sensors 811, 812, and 813 satisfy equation (8), and if they do not, the process proceeds to step S78, where command values for correcting the X-axis position and Y-axis position are output. Then, the process returns to the state immediately before step S74, and the posture of the robot hand body 300 is changed. If the detection values from sensors 811, 812, and 813 satisfy equation (8), the state becomes as shown in FIG. 7(j), and adjustment of the X-axis position and Y-axis position of the robot hand body 300 is completed. At this time, adjustment is made by the drive amount of the finger portions 305 and 306, and further adjustment is made.

In step S78, the command values for correcting the X-axis position and Y-axis position are calculated using the following formula:

By using the above flow, even if the workpiece W is tilted in the attitude of the robot hand body 300, the gripping attitude can be adjusted to match the workpiece W. Therefore, the gripping attitude of the robot hand body 300 can be adjusted without using a camera, for example. This reduces the need for adjustments associated with camera image processing, and makes it easy to set the gripping attitude to match the workpiece.

Second Embodiment
In the above-mentioned first embodiment, a case where a plurality of sensors of one type are used to adjust the posture of the robot hand body 300 has been described. However, the present invention can also be implemented in a case where the posture of the robot hand body 300 is adjusted using two types of sensors with different optical properties. In the following, the configuration of the hardware and the control system that are different from those in the first embodiment will be illustrated and described. Furthermore, it is assumed that the same configuration and operation as those in the first embodiment can be achieved with respect to the same parts as those in the first embodiment, and detailed description thereof will be omitted.

Figure 8 is a diagram showing an outline of the sensor in this embodiment. Sensor 811' is arranged adjacent to sensor 811 on the gripping portion 305' in the same plane. In this embodiment, sensor 811 is a proximity sensor, and sensor 811' is a TOF sensor. Although not shown in the figure for the sake of simplicity, similar to sensor 811, TOF sensors are arranged adjacent to each other in the same plane as the proximity sensors 812-816.

In general, proximity sensors have a short measurement range but high resolution. TOF sensors have a long measurement range but low resolution. To make use of their respective advantages and compensate for their disadvantages, they are used as follows. When the workpiece W1 is measured with each sensor, the sensor value D to be used for processing is determined by the following formula.

Here, D _prox is a measurement value of the proximity sensor, D _tof is a measurement value of the TOF sensor, and D _th is a threshold value. In this embodiment, D _th is preferably about 20 mm. More specifically, by utilizing the resolution characteristics of each sensor, the proximity sensor measures short distances and the TOF sensor measures long distances. By using the sensor value D according to formula (10), the distance between the workpiece W1 and each finger can be measured as in the first embodiment, and the position and orientation of the robot hand body 300 can be adjusted.

As described above, according to this embodiment, the position and orientation of the robot hand body 300 can be adjusted by measuring the distance between the workpiece W1 and each finger using two types of sensors. By measuring short distances with a proximity sensor and long distances with a TOF sensor, the measurement range can be made larger than when only one type of sensor is used, and short distances can be measured with high accuracy.

Third Embodiment
In the above-mentioned first embodiment, the case of a rectangular parallelepiped workpiece with high symmetry has been described. However, the present invention can also be implemented in the case of a convex workpiece with lower symmetry than a rectangular parallelepiped. In the following, the configuration of the hardware and control system that is different from that of the first embodiment will be illustrated and described. In addition, the same parts as those of the first embodiment are assumed to have the same configuration and function as those described above, and detailed description thereof will be omitted.

Figure 9 is a diagram showing an outline of the workpiece W2 according to this embodiment. It has a convex shape that is less symmetrical than a rectangular parallelepiped. Figure 10 is a diagram showing the outline of the configuration of the robot hand body 300' according to this embodiment.

A major difference from the first embodiment is that sensors 821 to 824 are arranged on the finger portion 306 as well as on the finger portion 305. The sensors 821 to 823 are arranged on the same plane in an area smaller than the thickness of the workpiece W2 in the Z-axis direction, and can measure the distance between the finger portion 306 and the gripping direction (X-axis direction) of the workpiece W2. The sensor 824 is arranged so as to be able to measure the distance between the finger portion 306 and the hand tip direction (Z-axis direction) of the base 600 or the mounting table S1. The sensors 831 and 832 are arranged on the palm of the robot hand body 300' and perpendicular to the palm so as to be spaced apart from each finger portion or the motion axis (axis A) of each finger portion by a length greater than the width of the workpiece W2 in the Y-axis direction. The above-mentioned arrangement makes it possible for each sensor to reliably measure the surface of the workpiece.

Next, the processing procedure for adjusting the gripping posture of the robot hand body 300' in this embodiment will be described using the flowcharts shown in Figures 4 and 6, as in the first embodiment. Also, Figure 11 is a state diagram of the robot hand body 300' in the control flowchart of Figure 6 in this embodiment. As a premise, the workpiece W2 is roughly placed on the mounting table S1 at a predetermined angle inclined with respect to the robot hand body 300'. Also, the workpiece W2 is started from a position where it can be gripped by the fingers 305 and 306 of the robot hand body 300'. Also, by measuring the workpiece W2 or the mounting table S1 with each sensor, the position and posture of the robot hand body 300 are appropriately changed and gripped. Also, the flow described below is executed by the CPUs of each control device communicating with each other, and the parts different from the first embodiment will be described in detail.

In FIG. 4, the control completion condition in step S40 in this embodiment is that the measurement values D of each sensor satisfy all of the following equations.

The subscript numbers of each measurement value D indicate which sensor, among the sensors 811 to 814, 821 to 824, 831, and 832, the sensor data acquired by which the distance measurement value relates to. D ₈₁₁ is the measurement value of sensor 811, D ₈₁₂ is the measurement value of sensor 812, D ₈₁₃ is the measurement value of sensor 813, and D ₈₁₄ is the measurement value of sensor 814. D ₈₂₁ is the measurement value of sensor 821, D ₈₂₂ is the measurement value of sensor 822, D ₈₂₃ is the measurement value of sensor 823, and D ₈₂₄ is the measurement value of sensor 824. D ₈₃₁ is the measurement value of sensor 831, and D ₈₃₂ is the measurement value of sensor 832.

L _a1 is the length between the measurement points of the sensors 811 and 813, and L _a2 is the length between the measurement points of the sensors 821 and 823. L _c is the length between the measurement points of the sensors 831 and 832. L _g1 is the length between the measurement points of the sensors 811 and 812, and L _g2 is the length between the measurement points of the sensors 821 and 822. It is assumed that the width D _ref immediately before gripping, the clearance h _ref with respect to the mounting table S1, the positioning tolerance ε _xyz , and the attitude determination tolerance ε _Txyz are set in the same manner as in the first embodiment.

As shown in FIG. 6, in step S71, the completion conditions for the X- and Y-axis postures are compared. In this embodiment, the completion conditions for step S71 are that all of the following expressions are satisfied (FIG. 11 (a) to (d)).

From FIG. 11(a), it is determined whether the detection values from sensors 811, 813, 821, and 823 satisfy equation (12), and if they do not, the process proceeds to step S75, where a command value for correcting the posture around the Y axis is output. Then, the process returns to just before step S71, and the posture of the robot hand main body 300' is changed. If the detection values from sensors 811, 813, 821, and 823 satisfy equation (12), the posture around the Y axis becomes the state shown in FIG. 12(b), and adjustment of the posture of the robot hand main body 300' around the Y axis is completed.

Similarly, from FIG. 11(c), it is determined whether the detection values from sensors 831 and 832 satisfy equation (12), and if they do not, the process proceeds to step S75, where a command value for correcting the posture around the X axis is output. Then, the process returns to the state immediately before step S71, and the posture of the robot hand main body 300' is changed. If the detection values from sensors 831 and 832 satisfy equation (12), the posture around the X axis becomes the state shown in FIG. 11(d), and adjustment of the posture of the robot hand main body 300' about the X axis is completed.

In step S75, the command values for posture correction around the X and Y axes are calculated using the following formula:

When adjustment of the posture around the X-axis and the posture around the Y-axis is completed in step S71, the process proceeds to step S72. In this embodiment, step S72 compares the Z-axis position with the completion condition in the following formula (Figure 11 (e) (f)).

From FIG. 11(e), it is determined whether the detection values from sensors 814 and 824 satisfy formula (14), and if they do not, the process proceeds to step S76, a command value for correcting the Z-axis position is output, and the process returns to just before step S72 to change the posture of the robot hand main body 300'. If the detection values from sensors 814 and 824 satisfy formula (14), the state becomes as shown in FIG. 11(f), and adjustment of the Z-axis position of the robot hand main body 300 is completed.

Here, in step S76 of this embodiment, the command value for Z-axis position correction is calculated using the following formula:

When the adjustment of the Z-axis position is completed in step S72, the process proceeds to step S73. In this embodiment, step S73 compares the posture around the Z-axis with the completion condition in the following formula (Figure 11 (g) (h)).

From FIG. 11(g), it is determined whether the detection values from sensors 811, 812, 821, and 822 satisfy formula (16), and if they do not, the process proceeds to step S77, where a command value for correcting the posture around the Z axis is output. Then, the process returns to the state immediately before step S73, where the posture of the robot hand main body 300' is changed. If the detection values from sensors 811, 812, 821, and 822 satisfy formula (16), the state becomes as shown in FIG. 11(h), and the adjustment of the posture of the robot hand main body 300' around the Z axis is completed.

In step S77 of this embodiment, the command value for posture correction around the Z axis is calculated using the following formula:

When adjustment of the posture around the Z axis is completed in step S73, the process proceeds to step S74. In this embodiment, step S74 compares the X-axis position and Y-axis position with the completion conditions (Figure 7 (i) (j)).

From FIG. 11(i), it is determined whether the detection values from sensors 811-813, sensors 821-823, and sensors 831 and 832 satisfy formula (18), and if they do not, the process proceeds to step S78, where command values for correcting the X-axis position and Y-axis position are output. Then, the process returns to the state immediately before step S74, and the posture of the robot hand main body 300' is changed. If the detection values from sensors 811-813, sensors 821-823, and sensors 831 and 832 satisfy formula (18), the state becomes as shown in FIG. 11(j), and adjustment of the X-axis position and Y-axis position of the robot hand main body 300' is completed. At this time, adjustment is made by the drive amount of the fingers 305 and 306, and further adjustment is made.

In step S78, the command values for correcting the X-axis position and Y-axis position are calculated using the following formula:

By using the above flow, even if a convex workpiece with low symmetry is tilted in the attitude of the robot hand main body 300', the gripping attitude can be adjusted to match the workpiece. Therefore, for example, the gripping attitude of the robot hand main body 300' can be adjusted without using a camera. This makes it possible to reduce adjustments associated with camera image processing, and makes it easy to set the gripping attitude to match the workpiece.

Other Embodiments
The processing procedures of the first to third embodiments described above are specifically executed by each control device. Therefore, a recording medium on which a software program capable of executing the above-mentioned functions is recorded can be supplied to a control device that integrates each control device, and a CPU that performs integrated processing reads and executes the program stored in the recording medium to achieve the above-mentioned functions. In this case, the program itself read from the recording medium realizes the functions of each of the above-mentioned embodiments, and the program itself and the recording medium on which the program is recorded constitute the present invention.

In addition, in each embodiment, the computer-readable recording medium is a ROM, a RAM, or a flash ROM, and the control program is stored in the ROM, RAM, or flash ROM. However, the present invention is not limited to such an embodiment. The control program for implementing the present invention may be recorded in any recording medium as long as it is a computer-readable recording medium. For example, a HDD, an external storage device, a recording disk, etc. may be used as a recording medium for supplying the control program.

In addition, in the various embodiments described above, the robot arm body 200 is described as using a multi-joint robot arm having multiple joints, but the number of joints is not limited to this. A vertical multi-axis configuration was shown as the type of robot arm, but a configuration equivalent to the above can also be implemented with a different type of joint, such as a parallel link type.

In addition, the fingers are parallel link mechanisms, which are highly effective when the fingers move in a direction perpendicular to the gripping direction (Z-axis direction) during a gripping operation. By executing the above-mentioned gripping posture adjustment control flow not only before gripping but also during the gripping operation, the position of the robot hand body in the Z-axis direction is adjusted to match the fingers moving in the Z-axis direction, reducing contact of the fingers with the mounting table or tray.

The various embodiments described above can also be applied to machines that can automatically perform movements such as stretching, bending, moving up and down, moving left and right, or rotating, or a combination of these movements, based on information stored in a storage device provided in the control device.

The present invention is not limited to the above-described embodiment, and many variations are possible within the technical concept of the present invention. Furthermore, the effects described in the embodiments of the present invention are merely a list of the most favorable effects resulting from the present invention, and the effects of the present invention are not limited to those described in the embodiments of the present invention.

REFERENCE SIGNS LIST 100 Robot system 200 Robot arm body 300, 300' Robot hand body 301 Hand motor driver 302 Encoder 303 Motor 304 Gear 305, 305', 306 Finger portion 307, 308 Slide guide 400 Robot arm control device 500 Robot hand control device 600 Base 700 Sensor control device 800 Sensor node 801 Power supply controller 802 Sensor data acquisition unit 811 to 816, 821 to 824, 831, 832 Sensor 811' TOF sensor S1 Placement table W1, W2 Workpiece

Claims (25)

A robot system including a robot hand having fingers and a palm on which the fingers are provided , a control device, a first sensor that acquires information regarding a distance between an object and the fingers, and a second sensor that is provided at a predetermined position on the palm and acquires information regarding a distance to the object ,
The control device includes:
During a gripping operation in which the finger units are moved to approach the object and grip the object, a position and/or a posture of the robot hand is controlled based on a detection result of the first sensor so that the finger units are aligned with the object ;
During a grasping operation in which the finger portions are moved to approach the object and grasp the object, a position and/or a posture of the robot hand is controlled based on a detection result of the second sensor so that the palm portion is aligned with the object .
A robot system comprising: 2. The robot system according to claim 1,
controlling a position and/or a posture of the robot hand so that the finger portion is aligned with a predetermined surface of the object;
A robot system comprising: 3. The robot system according to claim 1,
Controlling the position and/or posture of the entire robot hand;
A robot system comprising: 4. The robot system according to claim 1,
The first sensor is provided on the finger portion, and is provided in a range from a tip of the finger portion to a length of the object in a direction perpendicular to a surface on which the object is placed.
A robot system comprising: 5. The robot system according to claim 1,
The control device includes:
based on a detection result of the second sensor, controlling a position and/or a posture of the robot hand so that the palm portion is aligned with the object in a direction perpendicular to a direction in which the object is grasped by the finger portion;
A robot system comprising: 6. The robot system according to claim 1,
The second sensor is provided at a portion of the palm portion having an inclined surface inclined toward the finger portion.
A robot system comprising: 7. The robot system according to claim 1,
The finger portion is provided with a third sensor that acquires information regarding a distance between a surface on which the object is placed and a tip of the finger portion.
A robot system comprising: The robot system according to claim 7,
When gripping the object, the finger portion moves in a direction perpendicular to a surface on which the object is placed,
During a gripping operation in which the finger units are moved to approach the object and grip the object, a position and/or a posture of the robot hand is controlled based on a detection result of the third sensor so as to avoid interference between the finger units and a surface on which the object is placed.
A robot system comprising: 9. The robot system according to claim 1,
At least two first sensors are provided, and the first sensors are two types of sensors having different optical properties.
A robot system comprising: The robot system according to claim 9,
The at least two first sensor types are a proximity sensor and a time-of-flight sensor.
A robot system comprising: The robot system according to any one of claims 1 to 10,
The first sensor is provided on a surface of the finger portion different from a surface that comes into contact with the object.
A robot system comprising: The robot system according to claim 11,
A surface of the finger portion that comes into contact with the object is provided at a higher position than a surface on which the first sensor is provided.
A robot system comprising: The robot system according to any one of claims 1 to 12,
The control device includes:
controlling a position and/or a posture of the robot hand so that a first surface of the finger portion and a second surface of the object in contact with the first surface are substantially parallel to each other;
A robot system comprising: The robot system according to any one of claims 1 to 13 ,
The control device includes:
controlling a position and/or a posture of the robot hand so that a third surface of the palm portion and a fourth surface of the object facing the third surface are substantially parallel to each other;
A robot system comprising: 7. The robot system according to claim 1,
a third sensor is provided in the finger portion to acquire information regarding a distance between a surface on which the object is placed and a tip of the finger portion,
The robot hand includes a sensor node that controls the first sensor, the second sensor, and the third sensor in an integrated manner.
A robot system comprising: 16. The robot system according to claim 1,
The control device can automatically control the position and/or posture of the robot hand relative to the object.
A robot system comprising: 17. The robot system according to claim 1,
The object is disposed at a predetermined angle with respect to the robot arm on which the robot hand is provided .
A robot system comprising: 18. The robot system according to claim 1,
The robot hand has a first finger portion and a second finger portion as the finger portion,
The first sensor is provided on one of the first finger portion or the second finger portion, or on both the first finger portion and the second finger portion.
A robot system comprising: 9. The robot system according to claim 7,
The robot hand has a first finger portion and a second finger portion as the finger portion,
The third sensor is provided on one of the first finger portion or the second finger portion, or on both the first finger portion and the second finger portion.
A robot system comprising: A method for manufacturing an article, comprising the robot system according to any one of claims 1 to 19, comprising a robot arm provided with the robot hand, and using the robot hand and the robot arm to manufacture an article. A control method for a robot system including a robot hand having fingers and a palm on which the fingers are provided , a control device, a first sensor that acquires information regarding a distance between an object and the fingers , and a second sensor that is provided at a predetermined position on the palm and acquires information regarding a distance to the object ,
The control device,
During a gripping operation in which the finger portions are moved to approach the object and grip the object, a position and/or a posture of the robot hand is controlled based on a detection result of the first sensor so that the finger portions of the robot hand are aligned with the object;
During a grasping operation in which the finger portions are moved to approach the object and grasp the object, a position and/or a posture of the robot hand is controlled based on a detection result of the second sensor so that the palm portion is aligned with the object.
A control method comprising: A robot hand having a finger portion and a palm portion on which the finger portion is provided ,
a first sensor that acquires information regarding a distance state between the finger portion and the robot hand relative to an object , and a second sensor that is provided at a predetermined position on the palm portion and acquires information regarding the distance to the object ,
During a gripping operation in which the finger portions are moved to approach the object and grip the object, a position and/or a posture of the robot hand is controlled based on a detection result of the first sensor so that the finger portions of the robot hand are aligned with the object;
During a grasping operation in which the finger portions are moved to approach the object and grasp the object, a position and/or a posture of the robot hand is controlled based on a detection result of the second sensor so that the palm portion is aligned with the object.
A robot hand characterized by A method for controlling a robot hand having fingers and a palm on which the fingers are provided , comprising:
a first sensor that acquires information regarding a distance state between the finger portion and the robot hand relative to an object , and a second sensor that is provided at a predetermined position on the palm portion and acquires information regarding the distance to the object ,
The control device,
During a gripping operation in which the finger portions are moved to approach the object and grip the object, a position and/or a posture of the robot hand is controlled based on a detection result of the first sensor so that the finger portions of the robot hand are aligned with the object;
During a grasping operation in which the finger portions are moved to approach the object and grasp the object, a position and/or a posture of the robot hand is controlled based on a detection result of the second sensor so that the palm portion is aligned with the object.
A control method comprising: A control program capable of executing the control method according to claim 21 or 23 on a computer. A computer-readable recording medium storing the control program according to claim 24.

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