Control device and distributed control system

Abstract

To realize safe decentralized control based on information shared among a plurality of controllers.SOLUTION: A decentralized control system includes a plurality of controllers and executes control on a controlled device. One of the plurality of controllers transmits and receives information related to the plurality of controllers between itself and other controllers included in the plurality of controllers. The information includes quality information indicating control quality of the plurality of controllers. The controller stores the information in a storage region and adjusts instructions for the control on the controlled device based on the quality information stored in the storage region.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to a controller for a distributed control system and a distributed control system. [Background technology]

[0002] Various social infrastructure systems are equipped with control systems, which automate and streamline the social infrastructure systems by using multiple control devices that execute arithmetic processing.

[0003] The control device that constitutes such a control system acquires information such as various state quantities from detecting devices such as sensors installed in the field, and the central processing unit of the control device executes arithmetic processing.The control device then outputs control commands to operating devices such as motors and actuators installed in the field, controlling the operating devices in real time.

[0004] In addition, in large-scale social infrastructure systems, multiple control devices are connected via a common network to form a distributed control system. The distributed control system performs arithmetic processing based on information acquired from multiple detection devices installed in a vast field. Such a distributed control system divides the roles of a control device that performs arithmetic processing and a control device that outputs control commands, thereby achieving highly efficient control.

[0005] One method for synchronizing data between control devices in a distributed control system is the shared memory method. In the shared memory method, each control device that makes up the distributed control system has a shared memory in the memory installed in that control device, and the control device transmits the data stored in the shared memory to the other control devices. This allows data to be shared between the control devices, reducing the communication load between the control devices.

[0006] Furthermore, by synchronizing the time of multiple control devices and outputting control commands to the controlled objects at the same time, it is possible to achieve highly accurate real-time control, such as simultaneous processing of multiple processes or processing at a desired time in a chronological order. For this reason, time synchronization information is exchanged and each control device synchronizes its time.

[0007] Background art in this technical field is WO 2017 / 168750 (Patent Document 1). Patent Document 1 describes a control system that mutually transmits and receives status data indicating the operating mode, which is a control state, or the status of the functions provided by the device, and that, when restarted due to a failure, receives status data from another control device immediately before the failure and enters normal processing. [Prior art documents] [Patent documents]

[0008] [Patent Document 1] International Publication No. 2017 / 168750 Summary of the Invention [Problem to be solved by the invention]

[0009] In the communication system described in Patent Document 1, status data indicating the control status managed within each control device is shared. However, Patent Document 1 does not describe a technology for controlling the control amount and control timing according to the quality of the control status.

[0010] Therefore, the present invention aims to provide a control device that adjusts control commands to the controlled device 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. [Means for solving the problem]

[0011] A representative example of the invention disclosed in the present application is as follows: That is, 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. [Effects of the Invention]

[0012] According to one aspect of the present invention, stable control operation can be continued. Objects, configurations, and effects other than those described above will become apparent from the following description of the embodiments. [Brief explanation of the drawings]

[0013] [Figure 1] 1 is a diagram illustrating a configuration of a control system according to a first embodiment. [Figure 2] FIG. 2 is an explanatory diagram illustrating the configuration of a control device according to the first embodiment. [Figure 3] FIG. 2 is a diagram illustrating a functional configuration of a control device according to the first embodiment. [Figure 4] FIG. 4 is a diagram illustrating another functional configuration of the control device according to the first embodiment. [Figure 5A] 4 is a timing chart showing operation timings of the control device according to the first embodiment. [Figure 5B] 4 is a timing chart showing operation timings of the control device according to the first embodiment. [Figure 6A] FIG. 2 is a diagram illustrating an example of the contents of an information storage unit of the control device according to the first embodiment. [Figure 6B] FIG. 2 is a diagram illustrating an example of the contents of an information storage unit of the control device according to the first embodiment. [Figure 6C] FIG. 2 is a diagram illustrating an example of the contents of an information storage unit of the control device according to the first embodiment. [Figure 7] FIG. 3 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. [Figure 8] FIG. 4 is a diagram illustrating an example of time synchronization information of the control device according to the first embodiment. [Figure 9] 4 is a diagram illustrating a state of a time synchronization operation of the control device according to the first embodiment. FIG. [Figure 10] 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. [Figure 11] 4 is a flowchart of a process in which the control device according to the first embodiment calculates a control command and the control device shares the control command. [Figure 12] FIG. 10 is an explanatory diagram illustrating an example in which the control device according to the second embodiment is applied to an iron and steel system. [Figure 13] FIG. 10 is an explanatory diagram illustrating an example in which the control device according to the third embodiment is applied to an FA system. DETAILED DESCRIPTION OF THE INVENTION

[0014] Hereinafter, embodiments of the present invention will be described with reference to the drawings. Note that substantially the same or similar components are designated by the same reference numerals, and where explanations are redundant, redundant explanations may be omitted. [Example]

[0015] First, the configuration of a 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 form the distributed control system is arbitrary.

[0016] The 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 objects to be controlled) 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.

[0017] 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 TSN (Time Sensitive Network), or an industrial network standardized by IEC 61784 or the like can be used. The connection topology may also be a wired connection or a wireless connection such as a mobile phone network or wireless LAN.

[0018] The control device 100 includes a CPU (Central Processing Unit) 1001 and a memory 1002. Similarly, the control device 101 includes a CPU 1011 and a memory 1012, and the control device 102 includes a CPU 1021 and a memory 1022.

[0019] 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 acquired 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.

[0020] In addition, a sensor A7, a motor A8, and an actuator A9 are connected to the control device 100 via a field network 20. Similarly, a sensor B10 and a motor B11 are connected to the control device 101 via a field network 21, and a sensor C12 and a sensor C13 are connected to the control device 102 via a field network 22.

[0021] The field networks 20, 21, and 22 may be, for example, networks defined by IEC 61158. Digital signals and analog signals may be input and output by directly connecting the control device 100 and the like with the detection devices 7 and the operation devices 8 and 9. In this case, the control device 100 and the like with the detection devices 7 and the control targets 8 and 9 are connected by a plurality of input and output signal lines.

[0022] The control device 100 shares the sensing data input from the sensor 7 as shared data with the control devices 101 and 102 via the common network 1. Similarly, the control device 101 shares the sensing data input from the sensor 10 as shared data with the control devices 100 and 102 via the common network 1, and the control device 102 receives input from the sensors 12 and 13 and shares the shared data with the control devices 101 and 102 via the common network 1.

[0023] In particular, the control device 102 calculates control commands (command values) for, for example, the motor 8, the actuator 9, and the motor 11 from the shared input data, and shares the control commands with the control devices 101 and 102. On the other hand, the control device 100 controls the motor 8 and the actuator 9 according to the shared control commands, and similarly, the control device 101 controls the motor 11 according to the shared control commands.

[0024] The 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 rotation speed. Any of the control devices may not be connected to any of the operation 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 later).

[0025] Next, a configuration of the control device 100 according to the first embodiment will be described. Fig. 2 is an explanatory diagram illustrating a hardware configuration of the control device 100 according to the first embodiment. The control device 100 includes a CPU 1001, a memory 1002, a communication control unit 1003, an interface unit 1004, a nonvolatile storage medium 1005, a bus 1006, and an input / output unit 1007. Note that although 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.

[0026] 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 a predetermined function in accordance with a program.

[0027] The memory 1002 is a temporary storage area used when the CPU 1001 operates, and stores an operating system (hereinafter referred to as OS), application programs, etc. transferred from the non-volatile storage medium 1005. The memory 1002 also has an area for storing a program A that runs on each control device, an area for storing retained information A acquired by each control device (information acquired by each control device from a detection device or a control target), and an area for storing shared data (acquired information and control commands acquired by control A) that is shared between each control device via the common network 1.

[0028] The communication control unit 1003 executes data communication with the control devices 101 and 102 via the common network 1. As a data communication method, for example, a function of the MAC (Media Access Control) layer of the IEEE802.3 standard may be implemented. Note that examples of implementation of the communication control unit 1003 include an IC (Integrated Circuit), an FPGA (Field Programmable Gate Array), and a gate array. Furthermore, the communication control unit 1003 may be configured integrally with the CPU 1001.

[0029] Furthermore, the communication control unit 1003 has a function of exchanging time synchronization packets using a network and executing a time synchronization protocol. That is, the communication control unit 1003 has a timekeeping function when sending and receiving time synchronization packets, and a function of setting and adding correction values ​​to the time synchronization packets. IEEE1588, IEEE802.1AS, 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.

[0030] 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 function of IEEE802.3. The interface unit 1004 may be included in the communication control unit 1003.

[0031] In FIG. 2, the control device 100 has one communication control unit 1003 and one interface unit 1004, but may have a plurality of communication control units 1003 and a plurality of interface units 1004.

[0032] The nonvolatile storage medium 1005 is an information storage medium that stores, for example, an OS, applications, device drivers, programs that operate the CPU 1001, and the results of program execution. The nonvolatile storage medium 1005 is configured, for example, as a hard disk drive, a solid state drive, a flash memory, etc. The nonvolatile storage medium 1005 may also be configured as an easily removable external storage medium such as a USB memory or a solid state drive.

[0033] The input / output unit 1007 is an input / output interface that acquires information from devices connected to the control device 100, such as the sensor 7, and controls the motor 8 and the actuator 9. The input / output unit 1007 is equipped with, for example, the functions of the various field networks 20 described above, a digital input / output function, and an analog input / output function. Note that although FIG. 2 illustrates one signal line from the input / output unit 1007, multiple signal lines may be provided.

[0034] The bus 1006 communicatively connects the CPU 1001, the memory 1002, the communication control unit 1003, the nonvolatile storage medium 1005, and the input / output unit 1007.

[0035] Next, a functional configuration of a control device according to the first embodiment will be described. Fig. 3 is a diagram illustrating the functional configuration of a control device 100 according to the first embodiment. Other control devices may have similar functional configurations. The control device illustrated in Fig. 3 includes 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 holding unit 306, and a control command unit 307.

[0036] The time synchronization unit 300 executes a time synchronization procedure. The time synchronization protocols executed by the time synchronization unit 300 include the aforementioned IEEE1588, IEEE802.1AS, NTP, and SNTP. The time synchronization unit 300 synchronizes time with the control devices 101 and 102 using the time measured by the communication unit 301 (described later) when sending and receiving time synchronization packets. In other words, the time synchronization unit 300 synchronizes time with other control devices that constitute the distributed control system.

[0037] The time synchronization unit 300 may be realized by an application running on the CPU 1001, and the communication control unit 1003 may be realized by a hardware logic circuit using an IC or FPGA. The time synchronization unit 300 may also be configured by both the software of the CPU 1001 and the hardware of the communication control unit 1003. In this case, the measurement function of the transmission timing and reception timing of the time synchronization packet and the generation of the time synchronization packet format may be processed by the communication control unit 1003.

[0038] 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 that runs 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 about its own control device that it has acquired, and receives information about other control devices that it has acquired.

[0039] The synchronous update unit 302 holds the communication content received from the communication unit 301. The synchronous update unit 302 stores the held information in the shared data storage unit 303, which will be described later, in accordance with synchronous time information (including time notification and time notification interruption) notified from the time management unit 304, which will be described later. In other words, the synchronous update unit 302 stores the shared data (information) in the shared data storage unit 303 of its own control device in synchronization with the storage of the shared data (information) in the shared data storage unit 303 of the other control device, or in synchronization with the storage of the shared data (information) from the shared data storage unit 303 of the other control device.

[0040] 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 control device that receives the communication 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 later). The shared data storage unit 303 stores shared data transmitted from other control devices and stores control commands for the control target calculated by the calculation unit 401 (described later).

[0041] The time management unit 304 manages the synchronized time information in the information storage unit 306 (described later) in each control device based on the synchronized time.

[0042] The input / output control unit 305 acquires information from, for example, the sensor 7 connected to the control device 100, controls the motor 8 and the actuator 9, and inputs and outputs the information. In other words, the input / output control unit 305 acquires information from the detection device, and inputs and outputs information for controlling the control target.

[0043] 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 the sensor information, the information holding unit 306 holds synchronization time information notified from the time management unit 304 (sensor information with the time at which the sensor information was acquired added), 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 a clock master that serves as the clock reference. The amount of clock deviation may be a positive or negative value.

[0044] 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 store remaining life of the sensor, variation in the sensor value, amount of change in the sensor value, battery voltage value of the control device, operating time of the control device, etc. Furthermore, whether the acquired value is a constant value or a variable value, the range of possible values, an approximation formula or estimation method showing how the value fluctuates, etc. The information holding unit 306 also takes in and holds the information stored in the shared data storage unit 303.

[0045] The control command unit 307 adjusts the control command for the control object calculated by the calculation unit 401 (described later) 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 into account the amount of clock deviation. Alternatively, the control period is adjusted taking into account the amount of clock deviation. The control period is the period for issuing a control command.

[0046] 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.

[0047] 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 an 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 running out of control.

[0048] Furthermore, if the variation in the sensor values ​​deviates from an expected range or the amount of change in the sensor values ​​deviates from a relative range derived from an approximation formula for the change, and if the control command value calculated by the calculation unit 401 exceeds a predetermined range, the control command value may be adjusted to stop the control operation of the control device, for example. The control command value is included in the quality information indicating the control quality.

[0049] 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 although the control command unit 307 can be provided in all connected control devices, the adjustment of the control command can be performed, for example, in the control device with the most stable quality information, for example, the control device with the smallest clock deviation.

[0050] In this embodiment, an example has been shown in which the control devices are time-synchronized and periodically share quality information, but the present invention is not limited to this, and a method in which shared data is transmitted and received sequentially may also be used.

[0051] Next, a description will be given of another functional configuration of the 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.

[0052] 4 includes 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 holding unit 306, a control command 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 holding unit 306, and the control command unit 307 are the same as the functional units shown in FIG.

[0053] This control device particularly has a calculation unit 401 and corresponds to the control device 102. Note that the control device shown in FIG.

[0054] 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 executed using acquired information (sensor information) acquired by each control device, which is acquired 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 a control command. The calculated control command is stored in the shared data storage unit 303, and after its value is adjusted by the control command unit 307, it is shared with the other control devices (control device 100 and control device 101). In other words, the calculation unit 401 calculates a control command for the control target based on the shared data transmitted by the communication unit 301.

[0055] A control command assigned to the control device (control device 100 and control device 101) is read from the shared data storage unit 303 of the control device and output to a motor or actuator connected to the input / output unit 1007 shown in Fig. 2 (the input / output control unit 305 shown in Fig. 3). The calculation unit 401 is realized by software that runs on the CPU 1001.

[0056] Next, the operation timing of the control device according to the first embodiment will be described.

[0057] 5A and 5B are timing charts showing operation timings of the control device according to the first embodiment, and show a state in which the control system executes processing based on a predetermined shared period 521. FIG.

[0058] 5A shows that the control devices 100, 101, and 102 are sharing their respective shared data at the beginning of a sharing period 521. First, in a data sharing period 501, the control device 100 transmits the data it holds to the other control devices 101 and 102, and the data of the control device 100 is shared. When the data sharing period 501 of the control device 100 ends, in the next data sharing period 502, the control device 101 transmits the data it holds to the other control devices 100 and 102, and the data of the control device 101 is shared. When the data sharing period 502 of the control device 101 ends, in the next data sharing period 503, the control device 102 transmits the data it holds to the other control devices 100 and 101, and the data of the control device 102 is shared.

[0059] During data sharing periods 501 to 503, each control device performs 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 calculation or 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.

[0060] 5B shows that the control device 102 performs a control command calculation 531 and shares the calculation result (control command). 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 in the control device 102.

[0061] 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 device 100 and the control device 101), and the control device 100 and the control device 101 execute control of the corresponding motors and actuators based on the control commands transmitted from the control device 102. At this 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.

[0062] Next, an example of the contents of the information storage unit 306 of the control device according to the first embodiment will be described. Figures 6A to 6C are diagrams illustrating an example of the contents of the information storage unit 306 of the control device according to the first embodiment. Figures 6A to 6C illustrate an example of the contents of the storage area of ​​the information storage unit 306 of each control device at time t1.

[0063] Fig. 6A shows a holding area 60, which is an example of the contents of the holding area of ​​the information holding unit 306 of the control device 100. Fig. 6B shows a holding area 61, which is an example of the contents of the holding area of ​​the information holding unit 306 of the control device 101. Fig. 6C shows a holding area 62, which is an example of the contents of the holding area of ​​the information holding unit 306 of the control device 102.

[0064] The holding area 60 stores sensor information a acquired by the sensor 7 connected to the control device 100 and time synchronization information at together with the acquisition time. The holding area 61 stores sensor information b acquired by the sensor 10 connected to the control device 101 and time synchronization information bt together with the acquisition time. The holding area 62 stores sensor information c1, c2 acquired by the sensors 12 and 13 connected to the control device 102 and time synchronization information ct together with the acquisition time.

[0065] 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.

[0066] The calculation unit 401 of the control device 102 calculates a control command based on data information acquired from the other control devices and the control device itself, which is stored in the shared data storage unit 303 of the control device 102. That is, for this calculation, the sensor information of the sensor 7 acquired by the control device 100, the sensor information of the sensor 10 acquired by the control device 101, and the sensor information of the sensors 12 and 13 acquired by the control device 102 are used.

[0067] Next, a description will be given of an example of the contents of the shared data storage unit 303 of the control device according to the first embodiment. Fig. 7 is an explanatory diagram illustrating an example of the contents of the shared data storage unit 303 of the control device according to the first embodiment.

[0068] In the control device 102, before the calculation of the control command, 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.

[0069] Then, the control device 102 calculates a control command based on the sensor information, and stores the calculation result (control command value) in the shared data storage unit 303.

[0070] 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 .

[0071] Next, an example of time synchronization information of the control device according to the first embodiment will be described. Fig. 8 is a diagram showing an example of time synchronization information of the control device according to the first embodiment, which is extracted from the shared data 70 of Fig. 7. Time synchronization information 80 is shown when the control device 102 is the clock master, and for example, the amount of clock deviation from the clock master is stored. 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.

[0072] Similarly, the time synchronization bt stores the difference Δb1 in time change between the clock of the control device 101 and the clock of the control device 102, and the time difference Δb2. The time synchronization ct has a value of zero because the control device 102 is the clock master that provides the reference time. These values ​​are also stored in the holding area 60 of each control device. The CPU 1001 (calculation unit 401) adds the difference in time change and the time difference to correct the clock.

[0073] If the network becomes unstable and 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, an obstacle, radio wave interference, or momentary interruption or disconnection due to attenuation of radio wave strength due to movement, the control command unit 307 mentioned above will adjust the control command value by referencing the shared time synchronization information. At this time, the control command value is adjusted using this clock deviation as, for example, a 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.

[0074] FIG. 9 is a diagram showing the state of the time synchronization operation of the control device 100 according to the first embodiment, and shows a state in which the network state becomes unstable at time td.

[0075] Line 111 indicates 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 time changes of the clocks 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.

[0076] Next, a process of sharing shared information by the control device (control system) according to the first embodiment will be described. Fig. 10 is a flowchart of a process of sharing shared data (acquired information and time synchronization information) acquired from the sensor by the control device (control system) according to the first embodiment.

[0077] In step S91, the operation flow of the control system starts. In step S92, the control system is started. 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.

[0078] Next, a process in which the control device (control system) according to the first embodiment calculates a control command and the control device (control system) shares the control command will be described. Fig. 11 is a flowchart of the process in which the control device (control system) according to the first embodiment calculates a control command and the control device (control system) shares the control command.

[0079] 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, each control device shares the shared data, which corresponds to step S95.

[0080] 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.

[0081] As described above, according to the first embodiment, it is possible to provide a control device that can continue stable control operation and ensure product quality. [Example]

[0082] Next, an embodiment in which the above-described control device is applied to an iron and steel system will be described.

[0083] FIG. 12 is an explanatory diagram illustrating an example in which the control device according to the second embodiment is applied to an iron and steel system.

[0084] In the steel system, hot rolling equipment 800 for steel is controlled by control devices 100, 101, 102, 104, and 105. Control devices 100, 101, 102, 104, and 105 are controlled by a terminal 500 connected to a common network 600. Furthermore, control devices 100, 101, 102, 104, and 105, and terminal 500, all connected to common network 600, are time-synchronized with each other using control device 105 as a clock master, for example.

[0085] 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 .

[0086] 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 .

[0087] The control device 105 controls the winding control / thickness sensor / speed sensor unit 704, adjusts the rotation speed of the winding machine 805, and detects the thickness of the steel 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.

[0088] Here, even if the network connection state 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 the 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, after the connection is restored, operation can be safely resumed. [Example]

[0089] Next, an embodiment in which the above-described control device is applied to an FA (Factory Automation) control system will be described. Fig. 13 is an explanatory diagram illustrating an example in which the control device according to the third embodiment is applied to an FA system.

[0090] A server 520, a monitoring terminal 524, a wireless bridge 522, and a wireless bridge 523 are connected to the LAN 620. The control devices 120 and 121 are wirelessly connected to the wireless bridge 522, and the control devices 122 and 123 are wirelessly connected to the wireless bridge 523. This allows the control devices 120, 121, 122, and 123 to be controlled. The control devices 121, 122, and 123 are time-synchronized with each other using the control device 120 as a clock master.

[0091] The control device 120 controls a connected PLC (Programmable Logic Controller) 720, and the control device 121 controls a connected PLC 721. The control device 122 controls the PLC 722, and the control device 123 controls the PLC 723.

[0092] The PLC 720 controls the picking robot 822 , the PLC 721 controls the conveyor motor 823 and the camera 821 , the PLC 722 controls the painting robot 824 , and the PLC 723 controls the camera 825 .

[0093] Products (products to be manufactured) placed on the belt conveyor 826 are placed in a predetermined position and orientation (for example, the correct orientation of the product) by a picking robot 822 controlled by the PLC 720. The belt conveyor 826 moves at a predetermined speed by a conveyor motor 823 controlled by the PLC 721. Products moving on the belt conveyor 826 are photographed by a camera 821 controlled by the PLC 721, and this camera 821 observes whether or not the products are placed in the predetermined position.

[0094] PLC 721 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 PLC 722 paints the surface of the product. A camera 825 controlled by PLC 723 takes images of the painted product and observes whether the product has been painted correctly. PLC 723 acquires images of the product taken by camera 825 and performs an inspection to determine whether the product has been painted correctly.

[0095] 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.

[0096] Based on the input camera information, the control devices 121 and 122 select shared data, which is camera information for the same product, and the control device 120 calculates a control command for the picking robot 822 based on the shared data. Also, the control device 122 calculates a control command for the painting robot 824 based on the shared data.

[0097] A picking robot 822 places the product, a camera 821 photographs the product, and a 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.

[0098] Here, if the wireless connection between the control device 120 and the wireless bridge 522 becomes unstable, as described in the first embodiment, the movement speed of the belt conveyor 826, for example, can be reduced based on the time synchronization information in the shared memory, and the processing cycles of the picking robots 822 and 824 can be reduced accordingly, thereby enabling 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 a normal speed, and there is no need to reduce the painting speed. In other words, it is sufficient to reduce the processing speed to the minimum necessary extent.

[0099] As described above, control commands to controlled devices can be adjusted according to quality information indicating the quality of control shared among multiple control devices, thereby maintaining stable control operation and ensuring product quality and accuracy.

[0100] The control device of Example 1 can be used in various control systems such as FA systems, steel systems, water and sewage treatment systems, power generation control systems, elevator control systems, railway control systems, automobile control systems, and construction machinery control systems.

[0101] The present invention is not limited to the above-described embodiments, but includes various modifications and equivalent configurations within the spirit and scope 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 including 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, deleted, or replaced with other configurations.

[0102] 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 may be realized in software by a processor interpreting and executing a program that realizes each function.

[0103] Information such as programs, tables, and files that realize each function can be stored in a storage device such as a memory, a hard disk, or an SSD (Solid State Drive), or in a recording medium such as an IC card, an SD card, or a DVD.

[0104] In addition, the control lines and information lines shown are those that are considered necessary for explanation, and do not necessarily represent all the control lines and information lines that are necessary for implementation. In reality, it can be assumed that almost all components are interconnected. [Explanation of symbols]

[0105] 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...arithmetic 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

1. 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.

2. A control device included in a distributed control system that includes multiple 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.

3. A 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.

4. A 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.

5. A 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.

6. A 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.

7. A 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.

8. A 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.

9. A 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.

10. 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.

11. 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.

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