JP7796587B2 - Control device and distributed control system - Google Patents

Description

The present invention relates to a control device for a distributed control system and a distributed control system.

Various social infrastructure systems are equipped with control systems. Control systems use multiple control devices that perform computational processing to automate and streamline the control system, thereby automating and streamlining the social infrastructure systems.

The control devices that make up such control systems acquire information such as various state quantities from sensors and other detection devices installed in the field, and the control device's central processing unit performs calculations. The control device then outputs control commands to control devices such as motors and actuators installed in the field, controlling the controlled devices in real time.

In addition, control systems in large-scale social infrastructure systems consist of multiple control devices connected via a common network, forming a distributed control system. Distributed control systems perform calculations based on information acquired from multiple detection devices installed in vast fields. Such distributed control systems divide the roles of control devices that perform calculations and control devices that output control commands, achieving highly efficient control.

One method for synchronizing data between control devices in a distributed control system is the shared memory method. With the shared memory method, each control device that makes up the distributed control system has a shared memory installed in its own memory, and each control device transmits the data stored in the shared memory to the other control devices. This allows data to be shared between control devices, reducing the communication load between them.

Furthermore, by synchronizing the time of multiple control devices and outputting control commands to the controlled object at the same time, high-precision real-time control is possible, such as processing multiple processes simultaneously or processing them chronologically at desired times. For this reason, time synchronization information is exchanged and each control device synchronizes its time.

International Publication No. WO 2017/168750 (Patent Document 1) is a background technology in this field. Patent Document 1 describes a control system that mutually transmits and receives status data indicating the operating mode, which is the control state, or the status of the functions provided by the device, and, when restarted due to a failure, receives status data from another control device immediately before the failure and enters normal processing.

International Publication No. 2017/168750

The communication system described in Patent Document 1 shares status data indicating the control status managed within each control device. However, Patent Document 1 does not describe technology for controlling the amount of control or control timing according to the quality of the control status.

The present invention aims to provide a control device that adjusts control commands to controlled devices in accordance with quality information indicating the quality of control shared among multiple control devices, thereby maintaining stable control operation and ensuring product quality and accuracy.

A representative example of the invention disclosed in this application is as follows: A control device included in a distributed control system that includes multiple control devices and executes control over controlled devices includes: a communication unit that transmits and receives information about the multiple control devices, including quality information indicating the control quality of the multiple control devices, to and from other control devices of the multiple control devices; a shared data storage unit that stores the information; and a control command unit that adjusts control commands for the controlled devices based on the quality information stored in the shared data storage unit.

One aspect of the present invention allows for stable, continuous control operation. Issues, configurations, and advantages other than those described above will become clear from the following description of the examples.

FIG. 1 is a diagram illustrating a configuration of a control system according to a first embodiment. FIG. 2 is an explanatory diagram illustrating the configuration of a control device according to the first embodiment. FIG. 2 is a diagram illustrating a functional configuration of a control device according to the first embodiment. FIG. 4 is a diagram illustrating another functional configuration of the control device according to the first embodiment. 4 is a timing chart showing operation timings of the control device according to the first embodiment. 4 is a timing chart showing operation timings of the control device according to the first embodiment. FIG. 3 is a diagram illustrating an example of the contents of an information storage unit of the control device according to the first embodiment. FIG. 3 is a diagram illustrating an example of the contents of an information storage unit of the control device according to the first embodiment. FIG. 3 is a diagram illustrating an example of the contents of an information storage unit of the control device according to the first embodiment. FIG. 4 is an explanatory diagram illustrating an example of the contents of a shared data storage unit of the control device according to the first embodiment; FIG. 4 is a diagram illustrating an example of time synchronization information of the control device according to the first embodiment. FIG. 4 is a diagram illustrating a state of a time synchronization operation of the control device according to the first embodiment. 10 is a flowchart of a process in which the control device (control system) according to the first embodiment shares acquired information and time synchronization information acquired from a sensor. 4 is a flowchart of a process in which a control device according to the first embodiment calculates a control command and the control device shares the control command. FIG. 10 is an explanatory diagram illustrating an example in which a control device according to a second embodiment is applied to an iron and steel system. FIG. 10 is an explanatory diagram illustrating an example in which a control device according to a third embodiment is applied to an FA system.

Embodiments of the present invention will be described below with reference to the drawings. Note that substantially identical or similar components will be designated by the same reference numerals, and where explanations are redundant, they may be omitted.

First, the configuration of the control system according to Example 1 will be described. FIG. 1 is a diagram showing the configuration of the control system according to Example 1. In the control system according to Example 1, a control device (control A) 100, a control device (control B) 101, and a control device (control C) 102 are connected via a common network 1 to form a distributed control system. Note that the number of control devices that make up the distributed control system is arbitrary.

Control devices 100, 101, and 102 output control commands (control data such as control signals and command values) to control devices (controlled devices that are the target of control) such as motors 8 and 11 and actuators 9 installed in the field, and control the control devices in real time. In other words, the distributed control system includes control devices that execute control over the control devices.

The common network 1 is a network that improves the time determinism of communication delays between control devices by using time-slot communication based on time-division control. For example, a network that performs data communication using a communication method conforming to the IEEE standard known as a Time Sensitive Network (TSN), or an industrial network standardized by IEC 61784, etc., can be used. The connection can also be via a wired cable or a wireless connection such as a mobile phone network or wireless LAN.

The control device 100 has a CPU (Central Processing Unit) 1001 and memory 1002. Similarly, the control device 101 has a CPU 1011 and memory 1012, and the control device 102 has a CPU 1021 and memory 1022.

Memory 1002 is provided with an area for storing program A running on each control device, an area for storing retained information A acquired by each control device, and an area (shared data area) for storing shared data shared among all control devices via common network 1. The shared data here includes information such as acquired information obtained by control A100 and control commands received from other control devices. Similarly, memory 1012 is provided with an area for storing program B and retained information B, and an area for storing shared data, and memory 1022 is provided with an area for storing program C and retained information C, and an area for storing shared data.

In addition, sensor A7, motor A8, and actuator A9 are connected to control device 100 via field network 20. Similarly, sensor B10 and motor B11 are connected to control device 101 via field network 21, and sensors C12 and C13 are connected to control device 102 via field network 22.

The field networks 20, 21, and 22 may be networks defined by, for example, IEC 61158. Furthermore, the control device 100, etc. may be directly connected to the detection devices 7, etc. and the operation devices 8, 9, etc. to input and output digital and analog signals. In this case, the control device 100, etc. and each detection device 7, etc. and each control target 8, 9, etc. are connected by multiple input and output signal lines.

Control device 100 shares the sensing data input from sensor 7 as shared data with control devices 101 and 102 via common network 1. Similarly, control device 101 shares the sensing data input from sensor 10 as shared data with control devices 100 and 102 via common network 1, and control device 102 receives input from sensors 12 and 13 and shares the shared data with control devices 101 and 102 via common network 1.

In particular, control device 102 calculates control commands (command values) for, for example, motor 8, actuator 9, and motor 11 from the shared input data, and shares the control commands with control devices 101 and 102. Meanwhile, control device 100 controls motor 8 and actuator 9 using the shared control commands, and similarly, control device 101 controls motor 11 using the shared control commands.

Sensors 7, 10, 12, and 13 installed in the field are detection devices that detect and acquire information, which is a variety of state quantities such as flow rate, temperature, pressure, tension, and rotational speed. Any of the control devices may not be connected to any of the operating devices or detection devices. For example, there may be a control device that only generates control commands, or a control device that only operates as a clock master (described below).

Next, the configuration of the control device 100 according to the first embodiment will be described. Figure 2 is an explanatory diagram illustrating the hardware configuration of the control device 100 according to the first embodiment. The control device 100 has a CPU 1001, memory 1002, a communication control unit 1003, an interface unit 1004, a non-volatile storage medium 1005, a bus 1006, and an input/output unit 1007. Note that while the control device 100 will be described here, the control devices 101 and 102 also have the same basic configuration as the control device 100.

The CPU 1001 is a processor that controls the operation of each component of the control device 100. The CPU 1001 operates as a functional unit that realizes specified functions in accordance with a program.

Memory 1002 is a temporary storage area used when CPU 1001 operates, and stores the operating system (hereinafter referred to as OS) and application programs transferred from non-volatile storage medium 1005. Memory 1002 also has an area for storing program A running on each control device, an area for storing retained information A acquired by each control device (information acquired by each control device from detection devices and control targets), and an area for storing shared data shared between each control device via common network 1 (acquired information and control commands acquired by control A).

The communication control unit 1003 performs data communication with the control devices 101 and 102 via the common network 1. For example, the data communication method may implement the MAC (Media Access Control) layer functions of the IEEE 802.3 standard. Examples of implementations of the communication control unit 1003 include an IC (Integrated Circuit), an FPGA (Field Programmable Gate Array), and a gate array. The communication control unit 1003 may also be configured as an integrated unit with the CPU 1001.

Furthermore, the communication control unit 1003 has the function of exchanging time synchronization packets over the network and executing a time synchronization protocol. In other words, the communication control unit 1003 has functions such as timing when sending and receiving time synchronization packets, and setting and adding correction values to time synchronization packets. IEEE 1588, IEEE 802.1AS, NTP, and SNTP are used as such time synchronization protocols. The communication control unit 1003 also has a time management function based on synchronized time, and communicates synchronized time information to the control devices 101 and 102.

The interface unit 1004 transmits and receives data to and from the common network 1. The interface unit 1004 implements, for example, the physical layer functions of IEEE 802.3. Note that the interface unit 1004 may also be included in the communication control unit 1003.

In FIG. 2, the control device 100 has one communication control unit 1003 and one interface unit 1004, but it may have multiple communication control units 1003 and multiple interface units 1004.

The non-volatile storage medium 1005 is an information storage medium that stores, for example, the OS, applications, device drivers, programs that operate the CPU 1001, and the results of program execution. The non-volatile storage medium 1005 is composed of, for example, a hard disk drive, a solid state drive, or flash memory. The non-volatile storage medium 1005 may also be composed of an easily removable external storage medium such as a USB memory stick or a solid state drive.

The input/output unit 1007 is an input/output interface that acquires information from devices connected to the control device 100, such as sensors 7, and controls motors 8 and actuators 9. The input/output unit 1007 is equipped with, for example, the various field network 20 functions described above, as well as digital input/output functions and analog input/output functions. Note that while Figure 2 shows one signal line from the input/output unit 1007, there may be multiple signal lines.

The bus 1006 communicatively connects the CPU 1001, memory 1002, communication control unit 1003, non-volatile storage medium 1005, and input/output unit 1007.

Next, the functional configuration of the control device according to the first embodiment will be described. FIG. 3 is a diagram showing the functional configuration of the control device 100 according to the first embodiment. Other control devices may have a similar functional configuration. The control device shown in FIG. 3 has a time synchronization unit 300, a communication unit 301, a synchronization update unit 302, a shared data storage unit 303, a time management unit 304, an input/output control unit 305, an information retention unit 306, and a control command unit 307.

The time synchronization unit 300 executes the time synchronization procedure. The time synchronization protocols executed by the time synchronization unit 300 include the aforementioned IEEE 1588, IEEE 802.1AS, NTP, and SNTP. The time synchronization unit 300 synchronizes time with the control devices 101 and 102 using the time measured when a time synchronization packet is sent or received by the communication unit 301 (described below). In other words, the time synchronization unit 300 synchronizes time with the other control devices that make up the distributed control system.

The time synchronization unit 300 may be implemented as an application running on the CPU 1001, and the communication control unit 1003 may be implemented as a hardware logic circuit using an IC or FPGA. The time synchronization unit 300 may also be configured as both the software of the CPU 1001 and the hardware of the communication control unit 1003. In this case, the functions of measuring the transmission and reception timing of time synchronization packets and the generation of the time synchronization packet format may be processed by the communication control unit 1003.

The communication unit 301 is a functional unit that connects to the common network 1 and communicates based on the communication protocol of the common network 1. For example, the communication unit 301 is composed of software running on the CPU 1001, a communication control unit 1003, and an interface unit 1004. In other words, the communication unit 301 transmits information about its own control device to other control devices and receives information about other control devices from other control devices via the common network 1. The communication unit 301 transmits information acquired by its own control device regarding its own control device and receives information acquired by other control devices regarding other control devices.

The synchronization update unit 302 holds the communication content received from the communication unit 301. The synchronization update unit 302 stores the held information in the shared data storage unit 303, described below, using synchronization time information (including time notifications and time notification interrupts) notified by the time management unit 304, described below. In other words, the synchronization update unit 302 stores shared data (information) in the shared data storage unit 303 of its own control device in synchronization with the storage of shared data (information) in the shared data storage unit 303 of another control device, or in synchronization with the storage of shared data (information) from the shared data storage unit 303 of another control device.

The shared data storage unit 303 is a functional unit that stores shared data shared between each control device. A shared data area for each control device is allocated to the shared data storage unit 303. For example, each control device performs periodic broadcast communication, and the receiving control device identifies the control device that sent the communication and updates the corresponding shared data area. The shared data storage unit 303 stores information stored in the information storage unit 306 (described below). The shared data storage unit 303 also stores shared data transmitted from other control devices and stores control commands for the control target calculated by the calculation unit 401 (described below).

The time management unit 304 manages the synchronized time information in the information storage unit 306 (described below) in each control device based on the synchronized time.

The input/output control unit 305, for example, acquires information from sensors 7 connected to the control device 100, controls motors 8 and actuators 9, and inputs and outputs information. In other words, the input/output control unit 305 acquires information from detection devices and inputs and outputs information to control the controlled object.

The information holding unit 306 holds quality information indicating the control quality status. This information includes sensor information input from the input/output control unit 305. The information holding unit 306 is configured, for example, as a ring buffer. When holding sensor information, the information holding unit 306 holds synchronization time information (sensor information with the time at which the sensor information was acquired added) notified by the time management unit 304, that is, the sensor information and the time at which the sensor information was acquired. The information holding unit 306 may also receive and hold information from the time management unit 304 regarding the state of time synchronization, for example, the amount of clock deviation from the clock master that serves as the clock reference. The amount of clock deviation can be a positive or negative value.

The information holding unit 306 then stores the held data in the shared data storage unit 303. In addition to the above, the quality information may also include the remaining life of the sensor, the variance in the sensor value, the amount of change in the sensor value, the battery voltage value of the control device, and the operating time of the control device. Furthermore, information such as whether the acquired value is a constant value or a variable value, the range of possible values, and an approximation formula or estimation method indicating how the value will fluctuate may also be stored. The information holding unit 306 also imports and holds the information stored in the shared data storage unit 303.

The control command unit 307 adjusts the control commands for the control object calculated by the calculation unit 401 (described below) based on the quality information stored in the shared data storage unit 303. For example, based on the amount of clock deviation from the clock master, the control period is adjusted taking that deviation into account. Alternatively, the control command value is adjusted taking the amount of clock deviation into account. The control period is the period for issuing control commands.

In addition, the control command unit 307 adjusts the control period to slow down the control operation of the control device when the remaining life of the sensor or the operating time of the control device exceeds a specified value, or when the voltage value of the battery that drives the control device falls below a specified value.

The control command unit 307 may adjust the control command to perform degenerate operation when the quality information exceeds a predetermined threshold. Degenerate operation is operation in which some functions in normal operation are restricted, such as by stopping some functions or reducing the operating speed. For example, the control cycle can be adjusted to slow down the operation of the controlled device, or the control command value can be adjusted to limit the operable range of the controlled device. This makes it possible to prevent the controlled device from going out of control.

Furthermore, if the variation in the sensor value deviates from the expected range, or if the amount of change in the sensor value deviates from the relative range derived from the approximation formula for that change, and the control command value calculated by the calculation unit 401 exceeds a predetermined range, the control command value may be adjusted, for example, to stop the control operation of the control device. The control command value is included in the quality information indicating the control quality.

The adjusted control command value is stored in the shared data storage unit and is also transmitted to and shared with other control devices as shared data. Note that the control command unit 307 can be installed in all connected control devices, but the control command can be adjusted, for example, in the control device with the most stable quality information, such as the control device with the smallest clock deviation.

In this embodiment, an example is shown in which each control device is time-synchronized and periodically shares quality information, but this is not limited to this, and a method in which shared data is sent and received sequentially is also possible.

Next, other functional configurations of the control device according to Example 1 will be described. Figure 4 is a diagram showing other functional configurations of the control device according to Example 1.

The control device shown in FIG. 4 has a time synchronization unit 300, a communication unit 301, a synchronization update unit 302, a shared data storage unit 303, a time management unit 304, an input/output control unit 305 (not shown), an information retention unit 306, a control instruction unit 307, and a calculation unit 401. Note that the time synchronization unit 300, the communication unit 301, the synchronization update unit 302, the shared data storage unit 303, the time management unit 304, the input/output control unit 305, the information retention unit 306, and the control instruction unit 307 are the same as the functional units shown in FIG. 3.

This control device particularly has a calculation unit 401 and corresponds to control device 102. Note that the control device shown in FIG. 3 may also have the calculation unit 401. In other words, control device 102 has the calculation unit 401.

The calculation unit 401 calculates the necessary control commands to control the motors and actuators connected to the input/output control unit 305. The calculation process in the calculation unit 401 is performed using acquired information (sensor information) acquired by each control device, which is obtained from the shared data storage unit 303. The calculation unit 401 reads the acquired information (sensor information) stored in the shared data storage unit 303 and calculates control commands. The calculated control commands are stored in the shared data storage unit 303, and after their values are adjusted by the control command unit 307, they are shared with the other control devices (control device 100 and control device 101). In other words, the calculation unit 401 calculates control commands for the control object based on the shared data transmitted by the communication unit 301.

The control commands assigned to the control devices (control devices 100 and 101) are read from the shared data storage unit 303 of the control devices and output to the motors and actuators connected to the input/output unit 1007 shown in Figure 2 (the input/output control unit 305 shown in Figure 3). The calculation unit 401 is realized by software running on the CPU 1001.

Next, the operation timing of the control device in Example 1 will be explained.

Figures 5A and 5B are timing charts showing the operation timing of the control device according to Example 1, illustrating the state in which the control system executes processing based on a predetermined sharing period 521.

Figure 5A shows that the shared data of control device 100, control device 101, and control device 102 is shared at the beginning of sharing period 521. First, during data sharing period 501, control device 100 transmits the data it holds to the other control devices 101 and 102, and the data of control device 100 is shared. When data sharing period 501 for control device 100 ends, during the next data sharing period 502, control device 101 transmits the data it holds to the other control devices 100 and 102, and the data of control device 101 is shared. When data sharing period 502 for control device 101 ends, during the next data sharing period 503, control device 102 transmits the data it holds to the other control devices 100 and 101, and the data of control device 102 is shared.

During data sharing periods 501 to 503, each control device performs the necessary sensing 511 and time synchronization processing 512. Then, when the data sharing period 503 of the control device 102 ends, the CPU of each control device performs other processing such as calculations and control until the start time of the next sharing period 521. In other words, each control device acquires and stores 513 quality information such as sensor information and time synchronization information until the next data sharing time. The synchronization update unit 302 updates the shared data storage unit 303 of each control device every sharing period 521, and data is shared.

Figure 5B shows that the control device 102 performs a control command calculation 531 and shares the calculation results (control commands). When the data sharing period of the control device 101 ends, the control device 102 performs the control command calculation 531 based on the sensor information, which is the shared data transmitted from the control devices 100 and 101, and the sensor information at the control device 102.

Then, at the next data sharing time, the obtained calculation results (control commands) are shared (the control device 102 transmits the obtained calculation results (control commands) to the control devices 100 and 101), and the control devices 100 and 101 execute control of the corresponding motors and actuators based on the control commands transmitted from the control device 102. At that time, the control command unit 307 adjusts 532 the control command value based on the shared quality information, and the result is shared again as shared data.

Next, an example of the contents of the information storage unit 306 of the control device according to Example 1 will be described. Figures 6A to 6C are diagrams showing an example of the contents of the information storage unit 306 of the control device according to Example 1. Figures 6A to 6C show an example of the contents of the storage area of the information storage unit 306 of each control device at time t1.

Figure 6A shows holding area 60, which is an example of the contents of the holding area of information holding unit 306 of control device 100. Figure 6B shows holding area 61, which is an example of the contents of the holding area of information holding unit 306 of control device 101. Figure 6C shows holding area 62, which is an example of the contents of the holding area of information holding unit 306 of control device 102.

Sensor information a acquired by sensor 7 connected to control device 100 and time synchronization information at are stored in holding area 60 along with the time of acquisition. Sensor information b acquired by sensor 10 connected to control device 101 and time synchronization information bt are stored in holding area 61 along with the time of acquisition. Sensor information c1, c2 acquired by sensors 12 and 13 connected to control device 102 and time synchronization information ct are stored in holding area 62 along with the time of acquisition.

The information stored in the holding area 60 of each control device is stored in the shared data storage unit 303 of each control device.

The calculation unit 401 of the control device 102 calculates a control command based on data information acquired from other control devices and the control device itself, which is stored in the shared data storage unit 303 of the control device 102. In other words, this calculation uses the sensor information of sensor 7 acquired by the control device 100, the sensor information of sensor 10 acquired by the control device 101, and the sensor information of sensors 12 and 13 acquired by the control device 102.

Next, an example of the contents of the shared data storage unit 303 of the control device according to Example 1 will be described. Figure 7 is an explanatory diagram illustrating an example of the contents of the shared data storage unit 303 of the control device according to Example 1.

In the control device 102, before the control command is calculated, the sensor information (sensor value a) and time synchronization information (time synchronization at) acquired by sensor 7 in the control device 100, the sensor information (sensor value b) and time synchronization information (time synchronization bt) acquired by sensor 10 in the control device 101, and the sensor information (sensor values c1 and c2) and time synchronization information (time synchronization ct) acquired by sensors 12 and 13 in the control device 102 are stored in the shared data storage unit 303 as shared data 70.

The control device 102 then calculates a control command based on this sensor information and stores the calculation result (control command value) in the shared data storage unit 303.

Furthermore, the control command value is adjusted in the control command unit 307 based on the sensor information, and the adjusted value is stored in the shared data storage unit 303.

Next, an example of time synchronization information of the control device according to the first embodiment will be described. Figure 8 is a diagram showing an example of time synchronization information of the control device according to the first embodiment, which is time synchronization information extracted from the shared data 70 in Figure 7. This shows time synchronization information 80 when the control device 102 is the clock master, and stores, for example, the amount of clock deviation with the clock master. The time synchronization at stores the difference Δa1 in the time change between the clock in the control device 100 and the control device 102, and the time difference Δa2.

Similarly, the time synchronization bt stores the difference Δb1 in time change between the clock of control device 101 and control device 102, and the time difference Δb2. Since control device 102 is the clock master that provides the reference time, the time synchronization ct has a value of zero. These values are also stored in the holding area 60 of each control device. The CPU 1001 (calculation unit 401) adds the time change difference and the time difference to correct the clock.

If the network becomes unstable and the clock deviation increases due to factors such as a decrease in transmission speed, an increase in transmission delay time, fluctuations, packet loss, or in the case of wireless communication, obstacles, radio interference, or momentary interruptions or disconnections due to attenuation of radio wave strength due to movement, the aforementioned control command unit 307 will refer to the shared time synchronization information and adjust the control command value. At this time, the clock deviation is adjusted by using, for example, the control period, which is the control command value, or a correction coefficient for the control command value itself. This makes it possible to maintain stable control.

Figure 9 shows the state of time synchronization operation of the control device 100 according to Example 1, showing the state in which the network state becomes unstable at time td.

Line 111 represents the clock offset (time offset) between the control device 100 and the clock master. The time synchronization protocol described above detects the difference between the clock and the clock master, and the control device 100's clock is controlled to synchronize. At this time, as described above, the difference in the clock time changes and the time difference are shared by each control device. After time td, the clock offset increases for the reasons described above, but stable control can be achieved by adjusting the control command taking this offset into account.

Next, a process in which the control device (control system) according to Example 1 shares shared information will be described. Figure 10 is a flowchart of a process in which the control device (control system) according to Example 1 shares shared data (acquired information and time synchronization information) acquired from sensors.

In step S91, the operation flow of the control system starts.
In step S92, the control system is started up.
In step S93, the time synchronization unit 300 performs time synchronization with other control devices.
In step S94, each control device stores the acquired sensor information and time synchronization information in the information storage unit 306 together with the acquisition time.
In step S95, each control device stores the sensor information and time synchronization information stored in the information storage unit 306 in the shared data storage unit 303, and shares the information with other control devices as shared data.
These steps are then repeatedly executed for each sharing period.

Next, a process in which the control device (control system) according to Example 1 calculates a control command and the control device (control system) shares the control command will be described. Figure 11 is a flowchart of a process in which the control device (control system) according to Example 1 calculates a control command and the control device (control system) shares the control command.

In step S101, the operation flow of the control system starts.
In step S102, the control system is started.
In step S103, the time synchronization unit 300 performs time synchronization with other control devices.
In step S104, the control devices share the shared data, which corresponds to step S95.

In step S105, the calculation unit 401 calculates a control command.
In step S106, the control command unit 307 adjusts the control command.
In step S107, each control device shares the calculated and adjusted control command.
These steps are then repeated for each sharing period.

As described above, Example 1 provides a control device that can continue stable control operation and ensure product quality.

Next, we will explain an example in which the above-mentioned control device is applied to a steelmaking system.

Figure 12 is an explanatory diagram illustrating an example in which the control device according to Example 2 is applied to a steelmaking system.

In the steel system, hot steel rolling equipment 800 is controlled by control devices 100, 101, 102, 104, and 105. Control devices 100, 101, 102, 104, and 105 are controlled by terminal 500 connected to common network 600. Furthermore, control devices 100, 101, 102, 104, and 105, and terminal 500, all connected to common network 600, are time-synchronized using control device 105 as the clock master, for example.

The steel heated in the heating furnace 801 is fed into a hot rolling facility 800. The hot rolling facility 800 includes a roughing mill 802, a finishing mill 803, a cooling facility 804, and a winder 805.
The temperature of the heating furnace 801 acquired by the temperature sensor 700 is input to the control device 100 via the field network 601 .

The control device 101 controls the feed control/strip speed sensor unit 701, adjusts the rotation speed of the roughing mill 802, and detects the feed speed of the steel.
The control device 102 controls the rolling control/plate thickness sensor unit 702, adjusts the rotation speed and tension of the finishing rolling mill 803, and detects the thickness of the steel plate.
The temperature of the cooling equipment 804 acquired by the temperature sensor 703 is input to the control device 104 .

The control device 105 controls the winding control/thickness sensor/speed sensor unit 704, adjusts the rotation speed of the winder 805, and detects the thickness of the steel plate and the winding speed of the steel. The control device 105 also executes calculations of control commands for each controlled device.
Furthermore, each control device executes control in accordance with the above-mentioned operation flow.

Here, even if the network connection becomes unstable due to damage to the wired cable connecting the control device 105 and the common network 600, and the control device 105 loses connection with other control devices, the other control devices can determine the malfunction from the quality information shared by the control device 105, and the steel system can be safely shut down by the other control devices that remain connected. Furthermore, operation can be safely resumed after the connection is restored.

Next, an example in which the above-mentioned control device is applied to an FA (Factory Automation) control system will be described. Figure 13 is an explanatory diagram illustrating an example in which the control device according to Example 3 is applied to an FA system.

Connected to LAN 620 are server 520, monitoring terminal 524, wireless bridge 522, and wireless bridge 523. Control devices 120 and 121 are wirelessly connected to wireless bridge 522, and control devices 122 and 123 are wirelessly connected to wireless bridge 523. This allows control devices 120, 121, 122, and 123 to be controlled. Control devices 121, 122, and 123 are time-synchronized with control device 120 as the clock master.

Control device 120 controls the connected PLC (Programmable Logic Controller) 720, and control device 121 controls the connected PLC 721. Furthermore, control device 122 controls PLC 722, and control device 123 controls PLC 723.

PLC 720 controls the picking robot 822, PLC 721 controls the conveyor motor 823 and camera 821, PLC 722 controls the painting robot 824, and PLC 723 controls the camera 825.

Products (products to be manufactured) placed on the belt conveyor 826 are placed in a predetermined position and orientation (e.g., the correct orientation of the product) by a picking robot 822 controlled by PLC 720. The belt conveyor 826 moves at a predetermined speed by a conveyor motor 823 controlled by PLC 721. Products moving on the belt conveyor 826 are photographed by a camera 821 controlled by PLC 721, which observes whether the product has been placed in the predetermined position.

PLC721 acquires images of the product taken by camera 821 and performs an inspection to determine whether the product is installed in the specified position. A painting robot 824 controlled by PLC722 paints the surface of the product. A camera 825 controlled by PLC723 photographs the painted product and observes whether the product has been painted correctly. PLC723 acquires images of the product taken by camera 825 and performs an inspection to determine whether the product has been painted correctly.

Then, camera information (sensor information) from camera 821 is input to control device 121, and camera information (sensor information) from camera 852 is input to control device 123.

Then, based on this input camera information, control devices 121 and 122 select shared data, which is camera information for the same product, and control device 120 calculates control commands for picking robot 822 based on the shared data. Furthermore, control device 122 calculates control commands for painting robot 824 based on the shared data.

The picking robot 822 places the product, the camera 821 photographs the product, and the painting robot 824 paints the product. The time at which the camera 825 photographs the product is managed by the time management unit 304 of the control device.

If the wireless connection between the control device 120 and the wireless bridge 522 becomes unstable, as described in Example 1, the movement speed of the belt conveyor 826 can be reduced, for example, based on the time synchronization information in the shared memory, and the processing cycle of the picking robots 822 and 824 can be reduced accordingly, allowing stable control operation to continue without stopping the FA system. In this case, for example, when the painting robot 824 is painting, if the PLC 721 controls the belt conveyor to stop, the PLC 722 can instruct the painting robot 824 to paint at the normal speed, and there is no need to reduce the speed. In other words, it is sufficient to reduce the processing speed to the minimum necessary extent.

As described above, control commands to controlled devices can be adjusted based on quality information indicating the quality of control shared among multiple control devices, enabling stable control operation to be maintained and product quality and precision to be ensured.

The control device of Example 1 can be used in a variety of control systems, including factory automation systems, steelmaking systems, water and sewage treatment systems, power generation control systems, elevator control systems, railway control systems, automobile control systems, and construction machinery control systems.

The present invention is not limited to the above-described embodiments, and includes various modifications and equivalent configurations within the spirit of the appended claims. For example, the above-described embodiments have been described in detail to clearly explain the present invention, and the present invention is not necessarily limited to configurations that include all of the described configurations. Furthermore, part of the configuration of one embodiment may be replaced with the configuration of another embodiment. Furthermore, the configuration of another embodiment may be added to the configuration of one embodiment. Furthermore, part of the configuration of each embodiment may be added to, deleted from, or replaced with other configurations.

Furthermore, the aforementioned configurations, functions, processing units, processing means, etc. may be realized in part or in whole in hardware, for example by designing them as integrated circuits, or in software, by a processor interpreting and executing a program that realizes each function.

Information such as programs, tables, and files that implement each function can be stored in storage devices such as memory, hard disks, and solid-state drives (SSDs), or in recording media such as IC cards, SD cards, and DVDs.

Furthermore, the control lines and information lines shown are those considered necessary for explanation, and do not necessarily represent all control lines and information lines necessary for implementation. In reality, it is safe to assume that almost all components are interconnected.

1, 600...Common network, 20, 21, 22, 601...Field network, 1001, 1011, 1021...CPU, 1002, 1012, 1022...Memory, 7, 10, 12, 13...Sensor, 8, 11...Motor, 9...Actuator, 100, 101, 102, 104, 105, 120, 121, 122, 123...Control device, 1003...Communication control unit, 1004...Interface unit, 1005...Non-volatile storage medium, 1006...Bus, 1007...Input/output unit, 300...Time synchronization unit, 301...Communication unit, 302...Synchronization update unit, 303...Shared data storage unit, 304...Time management unit, 305...Input Output control unit, 306...information storage unit, 307...control command unit, 401...calculation unit, 520...server, 521...sharing cycle, 524...monitoring terminal, 700, 703...temperature sensor, 701...feed control/strip speed sensor, 702...rolling control/strip thickness sensor, 704...winding control/strip thickness sensor/strip speed sensor, 720, 721, 722, 723...PLC, 822...picking robot, 821...camera, 823...conveyor motor, 824...painting robot, 825...camera, 826...belt conveyor, 800...rolling equipment, 801...heating furnace, 802...roughing mill, 803...finishing mill, 804...cooling equipment, 805...winder.

Claims (11)

A control device included in a distributed control system that includes a plurality of control devices and executes control over controlled devices,
a communication unit that transmits and receives information about the plurality of control devices, including quality information indicating control quality of the plurality of control devices, between other control devices of the plurality of control devices;
a shared data storage unit for storing the information;
a control command unit that adjusts a control command for the controlled device based on the quality information stored in the shared data storage unit ,
The quality information includes a clock deviation amount relative to a time master device . A control device included in a distributed control system that includes a plurality of control devices and executes control over controlled devices,
a communication unit that transmits and receives information about the plurality of control devices, including quality information indicating control quality of the plurality of control devices, between other control devices of the plurality of control devices;
a shared data storage unit for storing the information;
a control command unit that adjusts a control command for the controlled device based on the quality information stored in the shared data storage unit,
The quality information includes an operating time of each of the plurality of control devices. The control device according to claim 1 or 2,
a time synchronization unit that synchronizes time with the other control devices via the communication unit;
a synchronization update unit that controls the storage of the information in the shared data storage unit of the control unit in synchronization with the storage of the information in the shared data storage unit of the other control unit. The control device according to claim 1 or 2,
The control device, wherein the control instruction unit adjusts a control period so that the operation of the controlled device slows down. The control device according to claim 1,
The control device wherein the control instruction unit adjusts the control period based on the amount of clock deviation. The control device according to claim 1 or 2,
The control device, wherein the control command unit adjusts a control command value so as to limit an operable range of the controlled device. The control device according to claim 1,
The control device, wherein the control command unit adjusts a control command value based on the amount of clock deviation. The control device according to claim 1 or 2,
The control device, wherein the control command unit stops control of the controlled device when a control command value exceeds a specified range. The control device according to claim 8,
The control device, wherein the control command unit resumes control of the controlled device when a control command value returns to a specified range. A distributed control system that performs control on a controlled device,
a plurality of control devices including a first control device;
The first control device
transmitting and receiving information about the plurality of control devices to and from other control devices of the plurality of control devices, the information including quality information indicating control quality of the plurality of control devices;
storing the information in a storage area;
adjusting a control command for the controlled device based on the quality information stored in the storage area;
A distributed control system in which the quality information includes a clock deviation amount relative to a time master device. A distributed control system that performs control on a controlled device,
a plurality of control devices including a first control device;
The first control device
transmitting and receiving information about the plurality of control devices to and from other control devices of the plurality of control devices, the information including quality information indicating control quality of the plurality of control devices;
storing the information in a storage area;
adjusting a control command for the controlled device based on the quality information stored in the storage area ;
A distributed control system, wherein the quality information includes an operating time of each of the plurality of control devices.