Ring Network Communication System

Abstract

To allow necessary data to be transmitted and received at an appropriate timing with a short control cycle.SOLUTION: A plurality of nodes 2 of a ring network communication system (1) include a heteronomous node (22) and an autonomous node (23). The heteronomous node (22) operates in a heteronomous mode in which data generated by a data generation unit (8) of its own node is transmitted as transmission data Dt only when reception data Dir received by a data reception unit 13 includes a data transmission request. The autonomous node (23) operates in an autonomous mode in which the data generated by the data generation unit (8) of the own node is transmitted as the transmission data Dt, regardless of whether the reception data Dir including the data transmission request is received. There is no need to transmit data including the data transmission request to the autonomous node, and a control cycle is shortened.SELECTED DRAWING: Figure 7

Description

[Technical Field]

[0001] The present invention relates to a ring network communication system in which a plurality of nodes are communicably connected via a ring network. [Background technology]

[0002] Conventionally, a ring network system in which multiple computers (network nodes) are connected to one another via a ring-shaped network is well known. In ring networks, a token ring communication method is known that can avoid signal collisions by allowing only the node that obtains the token to transmit data (see Patent Document 1). On the other hand, in the token ring system, multiple nodes cannot transmit data simultaneously on the network.

[0003] Therefore, the present applicant has proposed a ring network system in which multiple nodes can transmit data simultaneously (see Patent Documents 2 and 3). In these systems, a node has a data sending unit having a data transmission block that transmits data generated by the node itself as transmission data and a data relay block that relays transmission data transmitted from other nodes as relay data, and an output switching unit. The output switching unit switches between the transmission data and the relay data and outputs it as output data. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2001-326663 [Patent Document 2] Patent No. 6471021 [Patent Document 3] Patent No. 6527399 Summary of the Invention [Problem to be solved by the invention]

[0005] The communication system of Patent Document 2 may include, for example, one node as a main control unit (central control unit), nodes as multiple sub-control units (motor drive control units) that control motor drivers that drive joints, and nodes as multiple sub-control units (sensor control units) that control sensors. In a system in which multiple sensors are connected, such as a multi-link robot, the central control unit sends control commands to all motor drivers at a fixed control cycle and also sends request commands to acquire sensor data.

[0006] However, in the above-described conventional ring network communication system, as the number of nodes increases, data is transmitted continuously or frequently, which may hinder or delay the transmission of necessary data from other nodes.

[0007] For example, if many tactile sensors are connected to a network to measure the distribution of external forces that a robot receives over a specified area, the number of request commands increases depending on the number of sensors, and the control period must be long to transfer all the data.

[0008] In view of the above background, an object of the present invention is to enable necessary data to be transmitted and received at appropriate timing with a short control period in a ring network communication system. [Means for solving the problem]

[0009] In order to solve the above problem, one aspect of the present invention is a ring network communication system (1) in which a plurality of nodes (2) transmit data unidirectionally on a ring network (3) formed in a ring shape, and each node has a data generating unit (8) that generates data to be sent to other nodes, a data transmitting unit (12) having a data transmitting block (16) that transmits the data generated by the data generating unit of the node as generated data (Dp), and a data relay block (15) that transmits the data sent from the other nodes as relay data (Dr) to relay the data, and the data to be sent to the other nodes is determined by comparing the generated data transmitted by the data transmitting block with the The node is provided with an output switching unit (17) that switches between the relay data relayed by the data relay block and the relay data and outputs it as transmission data (Dt), and a data receiving unit (13) that receives the transmission data sent from the other node as reception data (Dir), and the plurality of nodes include a heteronomic node (22) that operates in a heteronomic mode in which data generated by the data generating unit of the node itself is sent as the transmission data only when a transmission request is included in the reception data received by the data receiving unit, and an autonomous node (23) that operates in an autonomous mode in which data generated by the data generating unit of the node itself is sent as the transmission data regardless of whether the reception data includes the transmission request.

[0010] According to this aspect, an autonomous node transmits data generated by its own data generator even without receiving reception data including a transmission request, so other nodes do not need to send data including a transmission request to the autonomous node. Therefore, the control period can be shortened by reducing the data transmission process. Furthermore, the autonomous node can transmit data at appropriate timing. This improves data transfer efficiency.

[0011] The plurality of nodes may have an operation mode switchable between the heteronomous mode and the autonomous mode, and may be configured to operate in the selected operation mode.

[0012] According to this aspect, each node switches between the heteronomous mode and the autonomous mode depending on the state, thereby reducing the data transmission process and shortening the control period.

[0013] In the above aspect, the plurality of nodes may be configured to switch the operating mode to a mode corresponding to the mode request when the received data received by the data receiving unit of the node includes a mode request requesting the heteronomic mode or the autonomous mode.

[0014] According to this aspect, for example, one node acting as a central control unit can switch the operating mode of other nodes.

[0015] In the above aspect, the plurality of nodes include a processing unit (4) that executes calculations and a network controller (5) that transmits and receives data, and the processing unit constitutes the data generation unit (8), and the heteronomic mode and the autonomous mode are switched by switching the operation mode of the data generation unit.

[0016] According to this aspect, the heteronomous mode and the autonomous mode can be easily switched by processing by the arithmetic processing unit.

[0017] In the above aspect, the node operating in the heteronomous mode may be a node (22) that drives and controls an actuator (6), and the node operating in the autonomous mode may be a node (23) that acquires sensor data from a sensor (7).

[0018] According to this aspect, the node that drives and controls the actuator transmits the data generated by the data generator (8) of the node only when it receives reception data including a transmission request. This reduces the data transmission process and shortens the control cycle.

[0019] In the above aspect, the data generation unit of the node that acquires the sensor data may be configured to generate data when the value of the acquired sensor data changes, and not to generate data when the value of the acquired sensor data does not change.

[0020] According to this aspect, the node that acquires the sensor data does not generate or transmit the data when the value of the sensor data does not change, which reduces the data transmission process and shortens the control cycle.

[0021] In the above aspect, the node operating as the heteronomous node may be a node that drives and controls an actuator, and may be configured to transition to the autonomous mode when a failure of the actuator is detected.

[0022] According to this aspect, a node operating as a heteronomous node can transition to autonomous mode even without a mode change request from another node, and can send out transmission data generated by the data generation unit in the event of an actuator failure.

[0023] In the above aspect, the ring network communication system is configured to control the operation of a robot, and at least one of the nodes may switch between the heteronomous mode and the autonomous mode in response to switching of the operation state of the robot.

[0024] According to this aspect, the operation mode of the node can be switched at an appropriate timing in response to the switching of the operating state of the robot, thereby effectively achieving both an appropriate reduction in the data transmission process and a shortened control cycle. [Effects of the Invention]

[0025] According to the above aspect, in a ring network communication system, it is possible to transmit and receive necessary data at appropriate timing with a short control period. [Brief explanation of the drawings]

[0026] [Figure 1] 1 is a schematic configuration diagram of a communication system according to an embodiment; [Figure 2] Functional block diagram of each node shown in Figure 1 [Figure 3] Data packet structure diagram [Figure 4] Configuration diagram of a communication system applied to a robot [Figure 5] FIG. 10 is an explanatory diagram of a control method according to a comparative example of a communication system; [Figure 6] FIG. 10 is an explanatory diagram of a control period according to a comparative example of a communication system; [Figure 7] FIG. 1 is an explanatory diagram of a control method for a communication system according to an embodiment; [Figure 8] FIG. 1 is an explanatory diagram of a control period of a communication system according to an embodiment; [Figure 9] 1A and 1B are explanatory diagrams illustrating a control period of a communication system, showing an embodiment and a modified embodiment, respectively; DETAILED DESCRIPTION OF THE INVENTION

[0027] Hereinafter, an embodiment of a ring network communication system (hereinafter simply referred to as a communication system 1) according to the present invention will be described with reference to the drawings.

[0028] Fig. 1 is a schematic configuration diagram of a communication system 1 according to an embodiment. As shown in Fig. 1, the communication system 1 is configured with a plurality of (four in the illustrated example) nodes 2 (2A, 2B, 2C, and 2D) and a ring network 3 that communicatively connects these nodes 2 in a ring shape. In this communication system 1, each node 2 has a CPU 4, which is a processing unit that executes arithmetic processing, and a network controller 5 that is configured to send data unidirectionally over the ring network 3. In other words, the plurality of nodes 2 are communicatively connected in a ring shape via the ring network 3 that communicates in one direction around the ring.

[0029] Each node 2 may be equipped with a storage device (memory such as ROM and RAM) in addition to a CPU 4 and a network controller 5, and is configured as a computer that executes various necessary processes. When a node 2 executes various processes, it means that the arithmetic processing device (CPU 4) is programmed to read necessary data and application software from the storage device (memory) and execute the predetermined arithmetic processing using the software.

[0030] The ring network 3 refers to a logical communication configuration and does not necessarily have to be a physical ring configuration. Also, being communicatively connected includes not only being physically connected via a communication line but also being connected wirelessly.

[0031] The plurality of nodes 2 perform arithmetic processing using software by the CPU 4, and control the operation of the corresponding actuator 6 made of hardware based on the data output by the arithmetic processing. Alternatively, the plurality of nodes 2 perform arithmetic processing using software by the CPU 4 on data output from the corresponding sensor 7 made of hardware, to generate and send data in predetermined units (e.g., packets). The plurality of nodes 2 may perform at least one of controlling the operation of the actuator 6 and sending data from the sensor 7, or may perform both.

[0032] Hardware refers to electrical devices electrically connected to a power source, and includes, for example, electric motors, solenoid valves, lighting fixtures, electrical elements, sensors 7, and drivers that control the power supplied to them. For example, the communication system 1 is mounted on a robot that operates autonomously or by remote control, and is configured as a distributed control system in which nodes 2 control each part of the robot. In this case, the power source may be mounted on the robot, or may not be mounted on the robot but connected to the robot via a power line.

[0033] Fig. 2 is a functional block diagram of each node shown in Fig. 1. As shown in Fig. 2, each node 2 has the above-mentioned network controller 5 configured by hardware, and a software-driven data generation unit 8 and control unit 9, which are functional units controlled by a CPU 4. The data generation unit 8 performs calculations using software by the CPU 4, and generates data D to be sent to other nodes 2. The control unit 9 performs calculations using software by the CPU 4 based on data received from other nodes 2, and drives and controls the actuators 6.

[0034] In each node 2, data sent from the upstream side of the ring network 3 is input to the network controller 5. In this embodiment, data is transmitted on the ring network 3 in packet units, i.e., as data packets. As shown in FIG. 3, a data packet is composed of a frame including a header, data, a trailer, and a CRC. The header is composed of a code, a start of packet (SOP), a number of hops (HOP), and a local node ID (SID). The trailer is composed of an end of packet (EOP), a free buffer size (FBC), a destination node ID (DID), and a packet priority (PRI).

[0035] 2, the network controller 5 has a data distributor 11. Data input to each node 2 (hereinafter referred to as input data Di) is distributed by the data distributor 11 to a data transmitter 12 and a data receiver 13, respectively.

[0036] The data generation unit 8 writes the generated data D for the other node 2 into the transmission / reception buffer 14, and transmits information about the data such as code and priority (hereinafter referred to as data information DI) to the data transmission unit 12.

[0037] The data transmitter 12 has a data relay block 15 and a data transmission block 16. When the input data Di distributed from the data distributor 11 is data that includes another node as a destination, the data relay block 15 transmits the input data Di as relay data Dr. The data transmission block 16 reads data D corresponding to the data information DI written by the data generator 8 from the transmission / reception buffer 14, and transmits it as generated data Dp.

[0038] When the input data Di distributed from the data distributor 11 is data to be received that includes the node itself as a destination, the data receiving unit 13 receives the input data Di as received data Dir and writes it to the transmission / reception buffer 14. The data receiving unit 13 also transmits data information DI of the received data Dir to the control unit 9. The received data Dir written to the transmission / reception buffer 14 is read by the control unit 9 based on the data information DI and provided to the control unit 9.

[0039] The relay data Dr transmitted from the data relay block 15 and the generated data Dp transmitted from the data transmission block 16 are input to the output switching unit 17. The output switching unit 17 switches the data to be sent to other nodes between the generated data Dp transmitted by the data transmission block 16 and the relay data Dr transmitted by the data relay block 15, and outputs it as transmission data Dt. Since the transmission data Dt is switched in this way and data collisions do not occur, multiple nodes 2 can send data onto the ring network 3 simultaneously.

[0040] It is not necessary for all nodes 2 to have all of these functions. For example, in a node 2 that does not control the operation of an actuator 6, the control unit 9 does not control the operation of the actuator 6 based on data received from other nodes 2. Instead, in this node 2, the data generation unit 8 may generate data including a data transmission request to the other nodes 2, or a control command including a request to drive the actuator 6 and a data transmission request to the other nodes 2. In a configuration in which one of multiple nodes 2 issues a transmission request or a control command to the other nodes 2, this node 2 functions as a central ECU (Electronic Control Unit) 21 (FIG. 4) that is a central control device that controls the other nodes 2.

[0041] Next, the communication system 1 applied to a robot will be described with reference to FIGS.

[0042] FIG. 4 is a configuration diagram of a communication system 1 applied to a robot. The robot has a multi-link structure having a plurality of joints. Each joint is configured to be rotatable around two axes. In other embodiments, the joints may be configured to be rotatable around one axis or three axes, or may be configured to be slidable in one or more directions. Each joint (more specifically, the link portion beyond each joint) constitutes an actuator 6 (FIG. 3). The actuator 6 has two motors 18 as a drive unit provided for each axis. In other embodiments, the actuator 6 has a pump as a drive unit, and may be driven by hydraulic pressure or air pressure.

[0043] The actuator 6 (more specifically, the link portion beyond each joint) is provided with sensors 7. The sensors 7 (7A, 7B) include a six-axis inertial sensor 7A and a contact sensor 7B. The six-axis inertial sensor 7A detects acceleration in three mutually orthogonal axis directions and angular velocity around the three axes. The contact sensor 7B has a matrix structure in which multiple sensor elements are arranged in two mutually orthogonal directions, and detects contact pressure or load in a predetermined area on the outer surface of the robot.

[0044] The communication system 1 includes a central ECU 21 consisting of a node 2, a plurality of motor driver ECUs 22 that drive and control the motors 18 of the actuators 6, and a plurality of sensor ECUs 23 that control the sensors 7 (7A, 7B). Each motor driver ECU 22 consists of a node 2, controls the motor 18 connected to its own node, and transmits data. Each sensor ECU 23 consists of a node 2, acquires sensor data from the sensors 7 (7A, 7B) connected to its own node, and transmits the sensor data. The sensors 7 (7A, 7B) may be connected to the motor driver ECU 22. In this case, the motor driver ECU 22 further acquires sensor data and transmits the sensor data.

[0045] Before describing the control method of the communication system 1 according to the embodiment, a conventional control method by the communication system 1 will be described with reference to Fig. 5 and Fig. 6. Fig. 5 is an explanatory diagram of a control method according to a comparative example of the communication system 1. As shown in Fig. 5, a central ECU 21 controls a motor driver ECU 22 and a sensor ECU 23.

[0046] Specifically, the central ECU 21 sends motor control commands (motor drive requests and data transmission requests) or data transmission requests to all other ECUs (motor driver ECU 22 and sensor ECU 23, i.e., other nodes 2) in order. The motor control commands (motor drive requests and data transmission requests) are sent to the motor driver ECU 22. The data transmission requests are sent to the sensor ECU 23. In FIG. 3, the order of data transmission is indicated by numbers in circles. The order of data transmission performed by the central ECU 21 is odd-numbered.

[0047] The motor driver ECU 22 that has received the motor control command controls the corresponding motor 18 based on the motor control command, and sends data including the state of its own node, the angle of the motor 18, the angular velocity of the motor 18, the motor torque (current value), etc. to the central ECU 21. The order of data transmission performed by the motor driver ECU 22 is an even number that is one greater than the order of the motor control command for its own node.

[0048] Upon receiving the data transmission request, the sensor ECU 23 acquires sensor data from the sensor 7 based on the data transmission request, and transmits data including the state of its own node, the sensor data, etc. to the central ECU 21. The data transmission performed by the sensor ECU 23 is an even number that is one greater than the order of the data transmission request to its own node.

[0049] Fig. 6 is an explanatory diagram of a control period according to a comparative example of the communication system 1. The vertical axis in Fig. 6 represents time. In the control according to the comparative example, the central ECU 21 sends data to all of the motor driver ECUs 22 and sensor ECUs 23 in this manner, and all of the motor driver ECUs 22 and sensor ECUs 23 send data to the central ECU 21. One cycle of control is made up of the data transmission by the central ECU 21 to all of the other nodes 2 (motor driver ECUs 22 and sensor ECUs 23) and the data transmission by all of the other nodes 2 to the central ECU 21. The control period is determined by the time required for one cycle of control.

[0050] Next, a control method for the communication system 1 according to the embodiment will be described with reference to Fig. 7 and Fig. 8. Fig. 7 is an explanatory diagram of the control method for the communication system 1 according to the embodiment. As shown in Fig. 7, the central ECU 21 controls the motor driver ECUs 22. Specifically, the central ECU 21 sends motor control commands (motor drive requests and data transmission requests) to all of the motor driver ECUs 22 in turn.

[0051] The motor driver ECU 22 that receives the motor control command controls the corresponding motor 18 based on the motor control command, and sends data including the state of the own node, the angle of the motor 18, the angular velocity of the motor 18, the motor torque (current value), etc. to the central ECU 21. In other words, the motor driver ECU 22 is a heteronomic node that operates in a heteronomic mode in which it sends the data generated by the data generation unit 8 of its own node as transmission data Dt only when the reception data Dir received by the data reception unit 13 in Fig. 2 includes a data transmission request.

[0052] On the other hand, the sensor ECU 23 operates autonomously to transmit data, rather than being controlled by the central ECU 21. That is, the sensor ECU 23 is an autonomous node that operates in an autonomous mode to transmit data generated by the data generator 8 of the own node as transmission data Dt, regardless of whether or not it receives reception data Dir including a data transmission request.

[0053] 8 is an explanatory diagram of the control cycle of the communication system 1 according to the embodiment. FIG. 8 corresponds to FIG. 6, and the vertical axis indicates time. In the control according to the embodiment, the central ECU 21 thus sends data to the motor driver ECU 22 operating in the heteronomous mode, but does not send data to the sensor ECU 23. The sensor ECU 23 operating in the autonomous mode sends data at appropriate timing.

[0054] In other words, the sensor ECU 23 operating in autonomous mode sends the data generated by the data generator 8 of its own node even if it does not receive the reception data Dir including a data transmission request. Therefore, the central ECU 21 does not need to send data including a data transmission request to the sensor ECU 23 operating in the autonomous node. This reduces the data transmission process, and the control period required for one cycle of control can be shortened compared to the comparative example in Figure 6. Furthermore, since the sensor ECU 23 operating in autonomous mode can send data at appropriate timing, data transfer efficiency is improved.

[0055] The sensor ECU 23 operating in autonomous mode may transmit data at appropriate timing for each control cycle. Alternatively, the sensor ECU 23 may transmit data when the detection value of the 6-axis inertial sensor 7A changes, or when the contact sensor 7B detects contact or when a contact value such as pressure or load changes. In particular, for the contact sensor 7B having multiple sensor elements arranged in a matrix, transmitting sensor data from all the sensor elements for each control cycle would increase the amount of data transmitted, resulting in a longer control cycle. Therefore, it is preferable for the sensor ECU 23 to operate in an event-driven manner, transmitting a signal when an event occurs, including a change in the value of the sensor 7, as described above.

[0056] 9A and 9B are explanatory diagrams of control periods of a communication system 1 according to an embodiment and a communication system 1 according to a modified embodiment that operates in an event-driven manner. In the embodiment of FIG. 9A, the sensor ECU 23 transmits sensor data to the central ECU 21 at each control period. In contrast, in the modified embodiment of FIG. 9B, the sensor ECU 23 transmits sensor data to the central ECU 21 when a contact event occurs. Therefore, compared to the embodiment of FIG. 9A, the amount of data transmitted when no event occurs is significantly reduced.

[0057] In these embodiments, the node 2 operating in the heteronomous mode is the motor driver ECU 22 that drives and controls the actuator 6, and the node 2 operating in the autonomous mode is the sensor ECU 23 that acquires sensor data from the sensor 7. In other words, the motor driver ECU 22 that drives and controls the actuator 6 transmits the generated data Dp generated by the data generator 8 of the own node only when it receives reception data Dir including a transmission request. This reduces the data transmission process and shortens the control cycle.

[0058] Furthermore, the data generation unit 8 of the sensor ECU 23 that acquires sensor data is configured to generate data when the value of the acquired sensor data changes, and not generate data when the value of the acquired sensor data does not change. In other words, the sensor ECU 23 that acquires sensor data does not generate or transmit data when the value of the sensor data does not change. This also reduces the data transmission process, making it possible to shorten the control cycle.

[0059] Returning to Fig. 6, another embodiment of the present invention will be described. In the above embodiment, the motor driver ECU 22 operates in a heteronomous mode, and the sensor ECU 23 operates in an autonomous mode. In another embodiment, these nodes 2 (the motor driver ECU 22 and the sensor ECU 23) have an operation mode that can be switched between the heteronomous mode and the autonomous mode.

[0060] Specifically, the data generator 8 has an autonomous mode in which data is generated at an appropriate timing regardless of whether a data transmission request is received, and a heteronomous mode in which data is generated only when a data transmission request is received. The data generator 8 is configured to send data in the selected operating mode. The appropriate timing may be, for example, when an event occurs that changes the value of the sensor 7.

[0061] In this way, by each node 2 switching between the heteronomous mode and the autonomous mode depending on the state, the data transmission process is reduced, and the control period is thereby shortened.

[0062] The operation mode is switched based on a control command from the central ECU 21. Specifically, in the central ECU 21, the data generation unit 8 generates data including a mode request for requesting the other node 2 to switch to a heteronomous mode or an autonomous mode, and the output switching unit 17 outputs this data as transmission data Dt. In the node 2 to which this data is sent, when the data receiving unit 13 receives the data including the mode request, the data generation unit 8 is configured to switch the operation mode to a mode corresponding to the mode request.

[0063] This allows the central ECU 21 to switch the operation mode of the other nodes 2.

[0064] As described above, in the nodes 2 other than the central ECU 21, the CPU 4, which is a calculation processing device, constitutes the data generation unit 8, and switches between the heteronomic mode and the autonomous mode by switching the operation mode of the data generation unit 8. This allows easy switching between the heteronomic mode and the autonomous mode through processing by the CPU 4.

[0065] Another embodiment will now be described. In this embodiment, the motor driver ECU 22 that controls the drive of the actuator 6 also operates in the heteronomous mode, and the sensor ECU 23 operates in the autonomous mode. Meanwhile, the motor driver ECU 22 is configured to detect a failure of the actuator 6, and transition to the autonomous mode when a failure of the actuator 6 is detected.

[0066] In this embodiment, the node 2 constituting the motor driver ECU 22 operating as a heteronomous node can transition to the autonomous mode without receiving a mode change request from another node 2 such as the central ECU 21. This allows the motor driver ECU 22 operating as a heteronomous node to send the transmission data Dt generated by the data generator 8 to the other node 2 when the actuator 6 fails.

[0067] Alternatively, the motor driver ECU 22 that drives and controls the actuator 6 may be configured to switch between the heteronomous mode and the autonomous mode in response to switching of the operating state of the robot.

[0068] For example, in the case of a walking robot, when a leg switches from a swing leg to a support leg, the motor driver ECU 22 switches from a heteronomic mode to an autonomous mode. Also, when a leg switches from a support leg to a swing leg, the motor driver ECU 22 switches from the autonomous mode to a heteronomic mode.

[0069] In the case of an arm robot, when the arm switches from an action of approaching an object (reaching: low-response action without contact with the environment) to an action of grasping an object (high-response action involving contact with the environment and humans), the motor driver ECU 22 switches from heteronomous mode to autonomous mode.

[0070] In this way, the node 2 switches between the heteronomous mode and the autonomous mode in response to the change in the operating state of the robot. This allows the node 2 to switch the operating mode at an appropriate timing. This effectively achieves both an appropriate reduction in data transmission processing and a shortened control cycle. Note that it is not necessary for all motor driver ECUs 22 to be configured in this way; the above effect can be obtained by configuring at least one motor driver ECU 22 in this way.

[0071] Although the description of the specific embodiment has been completed above, the present invention is not limited to the above embodiment and can be widely modified and implemented. For example, in the above embodiment, the communication system 1 applied to a robot has been described as an example, but the present invention can also be widely applied to systems other than robots. In addition, the specific configuration, arrangement, quantity, and control method of each member and part can be changed as appropriate within the scope of the spirit of the present invention. Meanwhile, not all of the components shown in the above embodiment are necessarily required and can be selected as appropriate. [Explanation of symbols]

[0072] 1: Communication Systems 2: Node 3: Ring network 4: CPU (Central Processing Unit) 5: Network Controller 6: Actuator 7: Sensor 7A: 6-axis inertial sensor 7B: Contact sensor 8: Data generation section 9: Control section 11: Data distributor 12: Data transmission unit 13: Data receiving unit 14: Send / receive buffer 15: Data relay block 16: Data transmission block 17: Output switching section 18: Motor (actuator) 21: Central ECU (node) 22: Motor driver ECU (node) 23: Sensor ECU (node) Dir: Received data Dp: Generated data Dr: Relay data Dt: Transmission data

Claims

1. A ring network communication system in which a plurality of nodes transmit data in one direction over a ring network formed in a ring shape, Each node is a data generation unit that generates data to be sent to other nodes; a data transmission unit having a data transmission block that transmits data generated by the data generation unit of the node as generated data, and a data relay block that transmits data sent from the other node as relay data to relay the data; an output switching unit that switches the data to be sent to the other node between the generated data transmitted by the data transmission block and the relayed data relayed by the data relay block, and outputs the data as transmission data; a data receiving unit that receives data transmitted from the other node as received data; The plurality of nodes a heteronomic node that operates in a heteronomic mode and transmits data generated by the data generation unit of the node as the transmission data only when the reception data received by the data reception unit includes a transmission request; an autonomous node that operates in an autonomous mode to send data generated by the data generating unit of the node as the transmission data regardless of whether the reception data includes the transmission request; A ring network communication system, wherein the plurality of nodes have an operating mode switchable between the heteronomous mode and the autonomous mode, and are configured to operate in the selected operating mode.

2. 2. The ring network communication system of claim 1, wherein the plurality of nodes are configured to switch the operating mode to a mode corresponding to the mode request when the received data received by the data receiving unit of the node includes a mode request requesting the heteronomic mode or the autonomous mode.

3. The plurality of nodes each include a processing unit that executes arithmetic processing and a network controller that transmits and receives data, 3. The ring network communication system according to claim 2, wherein the arithmetic processing unit constitutes the data generating unit, and switches between the heteronomic mode and the autonomous mode by switching the operation mode of the data generating unit.

4. 2. The ring network communication system according to claim 1, wherein the node operating in the heteronomous mode is a node that drives and controls an actuator, and the node operating in the autonomous mode is a node that acquires sensor data from a sensor.

5. 5. The ring network communication system according to claim 4, wherein the data generation unit of the node acquiring the sensor data is configured to generate data when the value of the acquired sensor data changes, and not generate data when the value of the acquired sensor data does not change.

6. 2. The ring network communication system according to claim 1, wherein the node operating as the heteronomous node is a node that drives and controls an actuator, and is configured to transition to the autonomous mode when a failure of the actuator is detected.

7. The ring network communication system of claim 1, wherein the ring network communication system is configured to control the operation of a robot, and at least one of the nodes switches between the heteronomous mode and the autonomous mode in response to switching of the operation state of the robot.

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