robot

Abstract

To detect abnormality of a communication cable before the communication cable is broken.SOLUTION: A robot 1 comprises: a plurality of links (7 to 10) which are connected in series to a base body (2) through a plurality of joints (21 to 24); a plurality of actuators (29) which drive the joints so as to relatively displace corresponding pairs of interconnected links: a plurality of controllers (32) which are decentralized and arranged at the base body and links, and control the actuators; communication cables 31 which are composed of optical cables interconnecting the controllers and transmitting information; and a plurality of light quantity measuring devices 40 which measure quantities I of light of light signals transmitted to the controllers through the communication cables 31. Each controller monitors the quantity I of light measured by the corresponding light quantity measuring device 40 to determine a state of the corresponding communication cable 31 based upon the quantity I of light.SELECTED DRAWING: Figure 3

Description

Technical Field

[0001] The present invention relates to a robot, and more particularly to a robot including a base body and a plurality of control devices distributed and arranged on a plurality of links connected in series to the base body.

Background Art

[0002] Conventionally, a ring network system in which a plurality of computers (network nodes) are connected to each other via a ring-shaped network is known. In this communication system, a token ring communication method is known in which signal collisions can be avoided by allowing only the node that has obtained a token to transmit data (see Patent Document 1). On the other hand, in the token ring method, a plurality of nodes cannot transmit data simultaneously on the network.

[0003] Therefore, the applicant has proposed a ring network system in which a plurality of nodes can transmit data simultaneously (see Patent Documents 2 and 3). In these systems, a node includes a data transmission unit (transmission unit) having a data transmission block for transmitting data generated by the node itself as transmission data and a data relay block for relaying transmission data transmitted from other nodes as relay data, and an output switching unit (transmission unit). The output switching unit outputs while switching one of the transmission data and the relay data as output data.

[0004] In the communication system of Patent Document 2, at least one of the data transmission unit and the output switching unit of each node has an error detection unit that detects abnormal data during data output in an on-the-fly manner. When the error detection unit detects abnormal data, the data transmission unit or the output switching unit having the error detection unit interrupts the data output in the middle and adds error data to the end of the interrupted data and outputs it.

Prior Art Documents

Patent Documents

[0005] [Patent Document 1] Japanese Patent Publication No. 2001-326663 [Patent Document 2] Patent No. 6471021 [Patent Document 3] Patent No. 6527399 [Overview of the Initiative] [Problems that the invention aims to solve]

[0006] When a communication system is applied to a robot, the network's communication cables are arranged across multiple links. In this case, the communication cables can break at the joints between links. In the ring network communication system described above, each node can freely output data. Therefore, it is conceivable to configure the system so that each node periodically transmits data, and by having the nodes monitor whether or not they are receiving data, it is possible to identify nodes that are not transmitting data (unable to deliver data) and pinpoint the location of the anomaly in the network. However, when an anomaly occurs, the node cannot determine whether the anomaly is due to a broken communication cable or a node failure.

[0007] In view of the above background, the present invention aims to enable the detection of abnormalities in a communication cable before it breaks, in order to suppress the occurrence of disconnection abnormalities. [Means for solving the problem]

[0008] To solve the above problems, one aspect of the present invention provides a robot (1) comprising: a plurality of links (7-10) connected in series to a base (2) via a plurality of joints (21-24); a plurality of actuators (29) that drive the joints to displace corresponding pairs of links connected to each other; a plurality of control devices (32) distributed on the base and the links and controlling the actuators; a communication cable (31) made of optical fiber that connects the control devices to each other and transmits information; and a plurality of light intensity measuring devices (40) that measure the light intensity (I) of an optical signal transmitted to the control devices via the communication cable, wherein each control device monitors the light intensity measured by the corresponding light intensity measuring device and determines the state of the corresponding communication cable based on the light intensity.

[0009] According to this embodiment, abnormalities in the communication cable can be detected before it breaks. Therefore, the robot can, for example, drive only the joints other than the joint through which the abnormal communication cable passes, thereby achieving degraded operation while maintaining high responsiveness.

[0010] In the above embodiment, each control device may determine that the state of the corresponding communication cable is abnormal when the decrease in the amount of light per unit time (ΔI / Δt) measured by the corresponding light intensity measuring device is greater than a predetermined first threshold (TH1).

[0011] According to this embodiment, it is possible to detect abnormalities in a communication cable caused by sudden bending deformation of the optical fiber.

[0012] In the above embodiment, each control device may determine that the state of the corresponding communication cable is abnormal when the amount of light measured by the corresponding light intensity measuring device is less than a predetermined second threshold (TH2).

[0013] According to this embodiment, it is possible to detect abnormalities in a communication cable caused by the deterioration of the durability of the optical fiber.

[0014] In the above embodiment, the control device constitutes a node (32) of a ring network communication system (30) that transmits data in one direction on a ring network formed in a ring shape, and each node has a data transmission unit (52) having a data generation unit (43) that generates data to be sent to other nodes, a data transmission block (56) that transmits the data generated by the data generation unit of the node as generated data (Dp), and a data relay block (55) that transmits relay data (Dr) to relay data sent from the other nodes, and the data to be sent to the other nodes is the generated data transmitted by the data transmission block and the data relay block The system includes an output switching unit (57) that switches between the relay data transmitted by the node and outputs it as transmitted data (Do), and a data receiving unit (53) that receives data sent from the other node as received data (Dir). At least one of the data transmission unit and the output switching unit of each node has an error detection unit (61) that detects abnormal data during on-the-fly data output. When the corresponding error detection unit detects the abnormal data, each node may determine that the state of the source node of the abnormal data is abnormal, and if there is an abnormality in the light intensity measured by the corresponding light intensity measuring device, it may determine that the state of the corresponding communication cable is abnormal.

[0015] According to this embodiment, when each node detects abnormal data, it can determine that the node that generated the data containing the abnormal data is in an abnormal state. Furthermore, each node can determine, based on the amount of light, that the state of the corresponding communication cable is abnormal. Therefore, the robot can, for example, drive only the joints other than the joint associated with the abnormality, thereby achieving degraded operation while maintaining high responsiveness.

[0016] In the above embodiment, each node sends out data indicating the abnormality of the source node when the corresponding error detection unit detects the abnormal data and determines that the state of the source node of the abnormal data is abnormal, and at least one of the nodes is a host node (32A) that transmits control commands for the corresponding actuator to the other nodes, and when the host node receives data indicating the abnormality of the source node, it does not need to transmit the control commands to the related source node.

[0017] According to this embodiment, the host node can perform degraded operation control that drives only a portion of the joint while maintaining high responsiveness by sending control commands only to nodes other than the source node of the data containing abnormal data.

[0018] In the above embodiment, each node sends out data indicating an abnormality in the communication cable when it determines that the state of the corresponding communication cable is abnormal based on the light intensity measured by the corresponding light intensity measuring device, and at least one of the nodes is a host node (32A) that transmits control commands for the corresponding actuator to the other nodes, and when the host node receives data indicating an abnormality in the communication cable, it does not need to transmit the control commands to the node associated with the abnormality in the communication cable.

[0019] According to this embodiment, the host node can perform degraded operation control that drives only a portion of the joint while maintaining high responsiveness by transmitting control commands only to nodes other than those related to the abnormality in the communication cable. [Effects of the Invention]

[0020] According to the above embodiment, it is possible to detect abnormalities in the communication cable before it breaks. [Brief explanation of the drawing]

[0021] [Figure 1] Front view of a robot according to an embodiment [Figure 2] Layout diagram of the communication system provided in the robot shown in FIG. 1 [Figure 3] Configuration diagram of each node shown in FIG. 1 [Figure 4] Configuration diagram of data packet [Figure 5] Functional block diagram of each node shown in FIG. 1 [Figure 6] Functional block diagram of the data relay block shown in FIG. 5 [Figure 7] Graph for explaining the abnormal modes of communication cables [Figure 8] Explanation diagram of the abnormal determination of communication cables in the communication system in the embodiment [Figure 9] Explanation diagram of the control method of the robot using the communication system in the embodiment

Embodiment for Carrying out the Invention

[0022] An embodiment of the robot 1 according to the present invention will be described with reference to the drawings.

[0023] As shown in FIG. 1, the robot 1 according to the embodiment is a two-legged walking humanoid robot that autonomously walks and runs, and includes a torso 2, a waist 3, a head 4, left and right arms 5, and left and right legs 6 that form a base. Each arm 5 is a multi-link mechanism composed of a shoulder 7, an upper arm 8, a forearm 9, and a hand 10 that form links. Each leg 6 is also a multi-link mechanism composed of a thigh 11, a lower leg 12, and a foot 13 that form links. The robot 1 carries an electrical component box 14 on the back of the torso 2. The electrical component box 14 houses a battery, a DC-DC converter, and the like.

[0024] The waist 3 is connected to the torso 2 by the waist joint 20. The shoulder 7 is connected to the torso 2 by the first shoulder joint 21. The upper arm 8 is connected to the shoulder 7 by the second shoulder joint 22. The forearm 9 is connected to the upper arm 8 by the elbow joint 23. The hand 10 is connected to the forearm 9 by the wrist joint 24. The thigh 11 is connected to the waist 3 by the hip joint 25. The lower leg 12 is connected to the thigh 11 by the knee joint 26. The foot 13 is connected to the lower leg 12 by the ankle joint 27. In other words, multiple links that make up the arms 5 and legs 6 are connected in series to the torso 2. The head 4 is connected to the torso 2 by the neck joint 28. In Figure 1, the approximate centers of each joint (20-28) are indicated by dashed circles. Each joint may be connected to a corresponding pair of links so as to be rotatable around one axis, or so as to be rotatable around two axes.

[0025] As shown in Figure 2, each joint is provided with a number of electric motors 29 corresponding to the number of connecting parts around the axis. Each joint changes the relative angle of the corresponding pair of links by rotating the connecting parts around the corresponding axis using the electric motors 29. Each electric motor 29 constitutes an actuator that drives the corresponding joint.

[0026] Robot 1 is equipped with multiple ring-shaped ring network communication systems (hereinafter simply referred to as "communication systems 30") (30A to 30E) as a network communication system for controlling the movement of each part. Specifically, it is equipped with a first communication system 30A for controlling the movement of the right arm 5, a second communication system 30B for controlling the movement of the left arm 5, a third communication system 30C for controlling the movement of the right leg 6, a fourth communication system 30D for controlling the movement of the left leg 6, and a fifth communication system 30E for controlling the movement of the head 4. Although not shown in the figures, Robot 1 may also be equipped with a sixth communication system for controlling the movement of the waist 3, etc.

[0027] The first communication system 30A comprises multiple nodes 32 (32A-32E), indicated by "N" in the figure, which are connected to each other via a communication cable 31. The multiple nodes 32 (32A-32E) are distributed across the links (7-9) that make up the torso 2 and the right arm 5. The second communication system 30B has a similar configuration, symmetrical to the first communication system 30A. The third communication system 30C comprises multiple nodes 32 distributed across the links (3, 11, 12) that make up the torso 2, waist 3 and the right leg 6. The multiple nodes 32 are connected to each other via a communication cable 31. The fourth communication system 30D has a similar configuration, symmetrical to the third communication system 30C. The fifth communication system 30E comprises multiple nodes 32 distributed across the torso 2 and the head 4, which are connected to each other via a communication cable 31.

[0028] Each communication system 30 is configured as a similar control system. Below, the configuration and control will be described in detail using the first communication system 30A as an example.

[0029] Node 32A, located on the torso 2 of the first communication system 30A, functions as a host node that generates and transmits control commands to other nodes 32B to 32E in its own communication system 30. Nodes 32B to 32E, other than the host node, each serve as a control device that controls one of the joints from the first shoulder joint 21 to the wrist joint 24, and are agent nodes that operate according to the control commands of the host node.

[0030] The agent nodes, nodes 32B to 32E, are located on the links from the shoulder 7 to the forearm 9. Some of the agent nodes may be located on the torso 2 or the hand 10. The first communication system 30A coordinately controls the movement of the right arm 5. Each of the first to fifth communication systems 30 forms a distributed control system in which nodes 32 are distributed to control various parts of the robot 1, which consists of multiple links connected in series to the torso 2 via multiple joints.

[0031] The communication cable 31 of the first communication system 30A is laid on the robot 1 so as to pass through four joints (21-24) from the torso 2 to the forearm 9. In the communication system 30, the signal transmission direction is predetermined. In the first communication system 30A, the signal is transmitted in the following order from node 32A, which forms the host node on the torso 2, to node 32B, which forms the agent node on the shoulder 7, to node 32C, which is on the upper arm 8, to node 32D and node 32E, which are on the forearm 9, and then returns to node 32A. In this embodiment, an optical fiber cable is used for the communication cable 31, and optical signals are transmitted through the communication cable 31.

[0032] In the first communication system 30A, node 32B controls the electric motor 29 that drives the first shoulder joint 21. Node 32C controls the electric motor 29 that drives the second shoulder joint 22. Node 32D controls the electric motor 29 that drives the elbow joint 23. Node 32E controls the electric motor 29 that drives the wrist joint 24.

[0033] Figure 3 is a diagram showing the configuration of each node shown in Figure 1. As shown in Figure 3, each node 32 includes a CPU 34 which constitutes the processing unit, a network controller 35, an optical receiving device 36, an optical transmitting device 37, an A / D converter 38, and memory (storage device) which is not shown. The network controller 35 is configured to send data D in one direction along the communication system 30.

[0034] The optical receiving device 36 is a device that receives optical signals transmitted from the upstream node 32 through the communication cable 31, and includes a photoelectric conversion unit 39 that converts optical signals into electrical signals, and an optical intensity measuring device 40 that measures the amount of light I. The data D converted into an electrical signal by the photoelectric conversion unit 39 is input to the network controller 35. If the destination of the data D is the local node, the data D is used by the CPU 34.

[0035] The analog signal indicating the light intensity I of the optical signal measured by the light intensity measuring device 40 is converted into a digital signal by the A / D converter 38 and supplied to the CPU 34. When the CPU 34 generates data D, it sends the data D to the network controller 35. The network controller 35 sends the data D sent from the CPU 34 and the data D sent from the optical receiving device 36 to the optical transmitting device 37.

[0036] The optical transmission device 37 is a device that converts electrical signals sent from the network controller 35 into optical signals and transmits them, and is equipped with an electro-optical conversion unit 41 that converts electrical signals into optical signals. The data D converted into optical signals by the electro-optical conversion unit 41 is transmitted to the downstream node 32 via the communication cable 31.

[0037] Each node 32 is a control device that controls a corresponding control target consisting of hardware, either according to a control command received from the host node or based on data D calculated by software processing by the CPU 34. Hardware refers to electrical devices electrically connected to a power supply, and may be a driver that controls the power supplied to the electric motor 29 that forms an actuator. Hardware may also include solenoid valves, lighting fixtures, electrical elements, and their drivers.

[0038] The data D transmitted over the communication system 30 consists of two types: normal data used for normal hardware control performed by the control unit 44 (described later), and interrupt data generated when controlling hardware without going through the control unit 44. Interrupt data takes precedence over normal data. A detailed explanation of the two types of data D is omitted here. If necessary, please refer to Japanese Patent Publication No. 2017-175231 by the present applicant.

[0039] Data D is transmitted over the ring network as a data packet, i.e., in packet units having the structure shown in Figure 4. As shown in Figure 4, a packet containing data D consists of a frame containing a header, data section (data D), trailer, and CRC (periodic redundancy check) in that order from the beginning. The header consists of a code, packet beginning (SOP), number of relays (HOP), and source node ID (SID). The trailer consists of packet end (EOP), free buffer size (FBC), destination node ID (DID), and packet priority (PRI). The data section has no size (bytes) limit and may be configured as a single block containing all the data D necessary for a series of commands. Alternatively, the data section may be limited to a predetermined size and may be one block of data D divided into multiple parts if the data D required for a series of commands is larger than the predetermined size.

[0040] Figure 5 is a functional block diagram of each node 32. As shown in Figure 5, each node 32 has the above-mentioned network controller 35, which is made up of hardware, and a software-driven data generation unit 43 and control unit 44, which are functional units of the CPU 34. The data generation unit 43 performs calculation processing using software by the CPU 34 to generate data D to be transmitted to other nodes 32, and data-related information such as codes and priorities to be added to the data D (hereinafter referred to as data information DI). The data generation unit 43 is configured to generate data D according to a predetermined repeating pattern (for example, at predetermined time intervals). The control unit 44 performs calculation processing using software by the CPU 34 based on the data D contained in packets transmitted from at least other nodes 32 and drives and controls the electric motor 29.

[0041] At each node 32, data D transmitted from the upstream side of the communication system 30 is input to the network controller 35. The network controller 35 has a data distributor 51. The data D input to each node 32 (hereinafter referred to as input data Di) is distributed by the data distributor 51 to the data transmission unit 52 and the data reception unit 53, respectively.

[0042] The data generation unit 43 writes the generated data D for the other node 32 to the transmit / receive buffer 54 and transmits data information DI to the data transmission unit 52.

[0043] The data transmission unit 52 includes a data relay block 55 and a data transmission block 56. The data relay block 55 transmits the input data Di distributed from the data distributor 51 as relay data Dr when the input data Di includes other nodes as destinations. The data transmission block 56 reads the data D corresponding to the data information DI written by the data generation unit 43 from the transmit / receive buffer 54 and transmits it as generated data Dp.

[0044] The data receiving unit 53 receives the input data Di distributed from the data distributor 51 as received data Dir and writes it to the transmit / receive buffer 54 when the input data Di includes its own node as a destination and should be received. The data receiving unit 53 also transmits the data information DI of the received data Dir to the control unit 44. The received data Dir written to the transmit / receive buffer 54 is read by the control unit 44 based on the data information DI and provided to the control unit 44.

[0045] The relay data Dr transmitted from the data relay block 55 and the generated data Dp transmitted from the data transmission block 56 are input to the output switching unit 57. The output switching unit 57 switches the data D to be sent to other nodes between the generated data Dp transmitted by the data transmission block 56 and the relay data Dr transmitted by the data relay block 55, and outputs it as transmitted data Do. Because the transmitted data Do is switched in this way and there are no data D collisions, multiple nodes 32 can simultaneously send data D onto the ring network.

[0046] It should be noted that not all nodes 32 need to possess all of these functions. For example, node 32A, which is a host node, does not control the operation of the electric motor 29, so the control unit 44 does not control the operation of the electric motor 29 based on the received data Dir received from other nodes 32. Instead, in node 32A, the data generation unit 43 generates data D which includes a data transmission request to other nodes 32 or a control command which includes a request to drive the electric motor 29 and a data transmission request to other nodes 32. The host node functions as a central control unit that controls other agent nodes.

[0047] Detailed explanations of each of these parts are omitted here, but if necessary, please refer to the applicant's Japanese Patent Publication No. 2017-11519 and Japanese Patent Publication No. 2017-175231. The data relay block 55 will be explained below.

[0048] As shown in Figure 6, in the data relay block 55, the error detection unit 61 performs relay determination on the input data Di. Specifically, the error detection unit 61 determines whether the input data Di was generated by the local node based on the local node ID (SID) of the data information DI. The error detection unit 61 also determines whether there is a relay abnormality based on the number of relays (HOP), specifically whether the number of relays is greater than or equal to the number of nodes on the network. Furthermore, the error detection unit 61 checks the CRC value of the input data Di and determines whether this value is an abnormal value (whether error display data is attached). The error detection unit 61 outputs the determination result to the relay control unit 62. In this way, the error detection unit 61 detects abnormal data during the on-the-fly output of data D.

[0049] The relay control unit 62 relays or discards the input data Di based on the judgment result of the error detection unit 61. Specifically, if the input data Di was generated by its own node, the relay control unit 62 discards the input data Di, considering it to have circulated once around the network ring. Also, if the number of relays of the input data Di is greater than or equal to the number of nodes, the relay control unit 62 determines that the input data Di is abnormal data. The relay control unit 62 then supplies an output data selection signal to the data selector 63 instructing the output of error display data and idle data so that the input data Di is discarded. If the CRC value is an abnormal value, the relay control unit 62 also determines that the input data Di is abnormal data and supplies an output data selection signal to the data selector 63 instructing the output of error display data and idle data so that the input data Di is discarded. The relay control unit 62 receives an output waiting signal Sw from the output switching unit 57 (see Figure 5).

[0050] On the other hand, if the error detection unit 61 determines that the input data Di is normal and should be relayed as relay data Dr, the relay control unit 62 increments the relay count of the relay data Dr and performs data selection control to the data selector 63. The relay control unit 62 also performs data input / output control to the data holding unit 64 in response to the output waiting signal Sw. The data selector 63 selects one of the idle data, the error display data, and the input data Di according to the command of the relay control unit 62 and writes the relay data Dr to the data holding unit 64. If the output waiting signal Sw is not input to the relay control unit 62 and the relay control unit 62 issues a command to output data, the data holding unit 64 transmits the relay data Dr it is holding.

[0051] The relay control unit 62 of the data relay block 55 is composed of hardware programmed to perform the predetermined operations described above. The hardware constituting the relay control unit 62 can include hardware logic circuits such as ASICs (Application Specific Integrated Circuits), PLDs (Programmable Logic Devices), and ASSPs (Application Specific Standard Produce). When using an ASIC, it may be a master-slice type such as a gate array or structured ASIC, or a custom type such as a cell-based ASIC. When using a PLD, it may be a PLD in the narrow sense, including Simple PLDs and CPLDs (Complex PLDs), or a PLD in the broad sense, further including FPGAs (Field-Programmable Gate Arrays). The hardware is preferably a PLD (Programmable Logic Device).

[0052] If the relay data Dr transmitted from the data holding unit 64 contains error display data, the node 32 that receives this relay data Dr determines that the state of the node 32 corresponding to the source (SID) of the relay data Dr is abnormal. In other words, each node 32 can determine that the node 32 that generated the relay data Dr containing this abnormal data is in an abnormal state.

[0053] Furthermore, when the host node, node 32A, receives this relay data Dr, node 32A does not send a control command to node 32, the source of the relay data Dr containing the abnormal data. In other words, node 32A can perform degraded operation control, which drives only a portion of the joint, while maintaining high responsiveness, by sending control commands only to node 32 other than node 32, the source of the relay data Dr containing the abnormal data.

[0054] In this embodiment, the error detection unit 61 is provided in the data relay block 55, but in other embodiments, the error detection unit 61 may be provided in the output switching unit 57.

[0055] Next, the nature of the abnormality in the communication cable 31 in the communication system 30 will be explained with reference to Figures 2 and 7. As shown in Figure 2, the communication cable 31 is routed so that it passes through a joint, and when the joint is driven by the electric motor 29, the communication cable 31 is bent. When the optical fiber undergoes a sudden bending deformation, the transmission of optical signals is hindered. As shown in Figure 7(A), when such a problem occurs, the amount of light I passing through the communication cable 31 decreases rapidly. If the bending deformation progresses further and the amount of light I decreases to the threshold I_th at which optical communication is possible, it becomes impossible to read the data D from the optical signal.

[0056] On the other hand, even if the communication cable 31 is not bent or deformed to the extent that it obstructs the transmission of optical signals, as shown in Figure 7(B), the optical fiber deteriorates in durability as the amount of joint movement (integral amount of drive angle) increases. Due to this deterioration in durability, the amount of light I passing through the communication cable 31 gradually decreases. If the joint movement continues and the amount of light I decreases to the threshold I_th at which optical communication is possible, it becomes impossible to read the data D from the optical signal.

[0057] As shown in Figure 3, the CPU 34 of each node 32 monitors the light intensity I of the optical signal measured by the light intensity measuring device 40 and determines the state of the corresponding communication cable 31 based on the light intensity I. This allows the node 32 to detect an abnormality before the communication cable 31 is broken. Therefore, as will be described later, the robot 1 can drive only the joints other than the joint through which the abnormal communication cable 31 passes, thereby achieving degraded operation while maintaining high responsiveness.

[0058] Specifically, the CPU 34 determines the state of the communication cable 31 as follows. Figure 8 is an explanatory diagram illustrating the abnormality detection of the communication cable 31 in the communication system 30 in an embodiment.

[0059] As shown in Figure 8, the CPU 34 monitors the decrease in light intensity I per unit time ΔI / Δt measured by the light intensity measuring device 40. The CPU 34 determines that the state of the corresponding communication cable 31 is abnormal when the decrease in light intensity I per unit time ΔI / Δt is greater than a predetermined first threshold TH1. This allows the CPU 34 to detect abnormalities in the communication cable 31 caused by rapid bending deformation of the optical fiber.

[0060] Furthermore, the CPU 34 monitors the light intensity I measured by the light intensity measuring device 40, and determines that the state of the corresponding communication cable 31 is abnormal when the light intensity I is less than a predetermined second threshold TH2. The second threshold TH2 is set to a value that is a predetermined amount α greater than the threshold I_th for optical communication. This allows the CPU 34 to detect abnormalities in the communication cable 31 caused by the deterioration of the durability of the optical fiber. Because the second threshold TH2 is set to a value that is greater than the threshold I_th for optical communication, the CPU 34 can detect abnormalities in the communication cable 31 before it becomes impossible to read data D from the optical signal.

[0061] In this way, each node 32 can determine that the state of the corresponding communication cable 31 is abnormal if there is an abnormality in the light intensity I measured by the corresponding light intensity measuring device 40.

[0062] When the CPU 34 determines that the state of the communication cable 31 is abnormal, the data generation unit 43 generates data D indicating that the state of the communication cable 31 is abnormal, and sends data D to the host node, node 32A. Upon receiving data D, node 32A executes degraded operation control, which drives only the joints that are not driven through the joints through which the abnormal communication cable 31 passes. In this way, the host node, node 32A, can achieve degraded operation while maintaining high responsiveness. This will be explained in detail below.

[0063] Figure 9 is an explanatory diagram of a control method for robot 1 using a communication system 30 in an embodiment. As shown in Figure 9, in this example, an abnormality in the communication cable 31 has occurred at node 32C, one of the agent nodes 32B to 32E, and node 32C has detected the abnormality in the communication cable 31 (step ST1). That is, as shown in Figure 2, an abnormality has occurred in the optical fiber of the communication cable 31 that transmits optical signals from node 32B to node 32C. This optical fiber passes through the second shoulder joint 22 (see Figure 2), and the electric motor 29 that drives the second shoulder joint 22 is controlled by node 32C. When node 32C detects the abnormality in the communication cable 31, it generates data D (abnormality notification) indicating the abnormality in the communication cable 31 and sends it to the host node, node 32A (step ST2).

[0064] When the host node, node 32A, receives a notification of an anomaly in the communication cable 31 from node 32C, it generates an operation that does not use the second shoulder joint 22 (step ST3). Subsequently, node 32A sends a control command to the agent node, node 32B (step ST4). When node 32B receives the control command for itself, it controls the electric motor 29 based on the control command (step ST5). Node 32A also sends a control command to the agent node, node 32D (step ST6). When node 32D receives the control command for itself, it controls the electric motor 29 based on the control command (step ST7). Furthermore, node 32A sends a control command to the agent node, node 32E (step ST8). When node 32E receives the control command for itself, it controls the electric motor 29 based on the control command (step ST9).

[0065] Thus, when the host node 32A receives data D indicating an abnormality in the communication cable 31, it does not send a control command to the node 32C associated with the abnormality (i.e., the node 32C that drives the joint through which the abnormal communication cable 31 passes). In other words, by sending control commands only to the nodes 32 (32B, 32D, 32E) other than the node 32C associated with the abnormality in the communication cable 31, node 32A can perform degraded operation control that drives only a portion of the joint while maintaining high responsiveness.

[0066] This concludes the description of specific embodiments, but the present invention is not limited to the above embodiments and can be broadly modified and implemented. For example, in the above embodiment, robot 1 is configured as a humanoid walking robot. On the other hand, robot 1 only needs to have multiple joints and may be configured as a robot other than a humanoid, a robot equipped with a driving unit such as wheels, tracks, or omni-wheels as a means of movement, or a robot that cannot move. Robot 1 does not need to be configured to perform actions programmed by a control device, and may be an avatar robot that acts as a human's doppelganger and is operated by remote control.

[0067] Furthermore, in the above embodiment, the communication system 30 is configured as a ring network communication system equipped with a ring-shaped communication cable 31, but other configurations such as bus type, star type, or mesh type may be adopted. In addition, the specific configuration, arrangement, quantity, or control procedure of each component or part can be changed as appropriate, as long as it does not depart from the spirit of the present invention. Moreover, not all of the components and procedures shown in the above embodiment are necessarily essential, and can be selected as appropriate. [Explanation of symbols]

[0068] 1: Robot 2: Body (base body) 7: Shoulder area (link) 8: Upper arm (link) 9: Forearm (link) 10: Hand (link) 21: First shoulder joint 22: Second shoulder joint 23: Elbow joint 24: Wrist 29: Electric motor (actuator) 30: Communication systems (ring network communication systems) 30A~30E: Communication systems 1 to 5 31: Communication cable 32: Node (control device) 32A: Node (Host Node) 32B~32E: Nodes (Agent Nodes) 34:CPU 35: Network Controller 36: Optical receiving device 37: Optical Transmitter 38: A / D converter 39: Photoelectric conversion unit 40: Light intensity measuring device 41: Light Conversion Unit 43: Data Generation Unit 44: Control Unit 52: Data transmission unit 53: Data receiving unit 55: Data relay block 56: Data transmission block 57: Output switching section 61: Error detection unit D: Data DI: Data Information Di: Input data Dir: Received data Do: Send data Dp: Generated data Dr: Relay data I: Light intensity ΔI / Δt: Decrease amount TH1: First threshold TH2: Second threshold

Claims

1. It is a robot, Multiple links connected in series to the base via multiple joints, A plurality of actuators that drive the joint to displace a relative pair of the links that are connected to each other, Multiple control devices are distributed and arranged on the base and the link to control the actuator, A communication cable consisting of optical fibers that connects the aforementioned control devices to each other and transmits information, The system comprises a plurality of light intensity measuring devices that measure the amount of light in an optical signal transmitted to the control device via the aforementioned communication cable, The aforementioned base includes a torso and a waist, Each control device monitors the light intensity measured by the corresponding light intensity measuring device, and determines the state of the corresponding communication cable based on the light intensity. The control device constitutes a node in a ring network communication system that transmits data in one direction on a ring network formed in a ring shape. Each node, 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 its own node as generated data, and a data relay block that transmits data sent from other nodes as relay data, An output switching unit that switches the data to be sent to the other node between the generated data sent by the data transmission block and the relay data sent by the data relay block, and outputs it as transmission data, The system includes a data receiving unit that receives data transmitted from the aforementioned other nodes as received data, At least one of the data transmission unit and the output switching unit of each node has an error detection unit that detects abnormal data during on-the-fly data output. Each node, when the corresponding error detection unit detects the abnormal data, determines that the state of the source node of the abnormal data is abnormal, and if there is an abnormality in the light intensity measured by the corresponding light intensity measuring device, determines that the state of the corresponding communication cable is abnormal. Each node, when it determines that the state of the corresponding communication cable is abnormal based on the light intensity measured by the corresponding light intensity measuring device, sends out data indicating the abnormality of the communication cable. A robot characterized in that at least one of the nodes is a host node provided on the torso that transmits control commands for the corresponding actuator to the other nodes, and when the host node receives data indicating an abnormality in the communication cable, it does not transmit the control commands to the node that drives the joint through which the abnormal communication cable passes.

2. The robot according to claim 1, wherein each control device determines that the state of the corresponding communication cable is abnormal when the amount of decrease per unit time of the light quantity measured by the corresponding light quantity measuring device is greater than a predetermined first threshold.

3. The robot according to claim 1 or 2, wherein each control device determines that the state of the corresponding communication cable is abnormal when the amount of light measured by the corresponding light intensity measuring device is less than a predetermined second threshold.

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