JP2013232847A - Communication system, communication device, relay device, communication device control method, relay device control method and program - Google Patents

Abstract

A part of a transmission line of a bus network that returns a response in a predetermined time while wirelessly relaying a retry while reducing the cost of changing an existing node.
A relay device that relays communication between a first terminal connected to a bus network, a second terminal connected to another bus network, and the first terminal and the second terminal. The first terminal includes a dummy data adding unit for adding dummy data to data to be transmitted, and dummy data addition so as to add dummy data to data to be transmitted via the relay device A dummy data addition control unit that controls the unit, the second terminal includes a response unit that responds in a predetermined time after receiving data from the first terminal, and the relay device receives the response from the first terminal. A dummy data removing unit is provided that removes dummy data included in data transmitted to the second terminal and relays the dummy data.
[Selection] Figure 10

Description

  The present invention relates to a communication system, a communication apparatus, a relay apparatus, a communication apparatus control method, a relay apparatus control method, and a program for relaying a part of a transmission path of a bus network.

  In recent years, in the fields of industrial equipment and information equipment, replacement from wired communication to wireless communication has been performed in order to reduce wiring of equipment. On the other hand, the cost of components required for wireless communication tends to be higher than that for wired communication, and there is a need for a technique for wirelessly relaying only necessary portions without replacing everything wirelessly. For example, a movable part of a wired transmission path has problems such as a decrease in durability and a twist, and therefore, there is a need for wireless relaying even if the movable part alone costs a little.

  By the way, many standard communication protocols stipulate that, for delivery confirmation, a node that has received data outputs an ACK response indicating that the data has been correctly received to the transmission line in a predetermined time. When a wired communication to which such a communication protocol is applied is wirelessly relayed, a delay time for the relay is added, so that if a relay is performed as it is, a response may not be output within a predetermined time.

  Therefore, Patent Document 1 proposes a technique for outputting a response at a correct timing for a retry without outputting a response to the first data transmission.

  Patent Document 2 proposes a technique for securing time for response by adding dummy data to the end of data to be transmitted.

  On the other hand, bus-type networks are widely used in the field of industrial equipment. The bus type network is a network in which one wired transmission path is shared by a plurality of nodes for communication. As an example of such a network, Non-Patent Document 1 discloses a CAN (Controller Area Network). Even in CAN, it is specified that a receiving node outputs an ACK response in a predetermined time.

JP 2008-109711 A JP 2006-197045 A

CAN Specification 2.0 (Robert Bosch GmbH)

  However, when relaying a part of a transmission path of a bus type network that returns a response in a predetermined time using wireless communication, there are the following problems. First, in the method of outputting a response to a retry, a retry occurs every time, so that the bus occupation time increases, and other nodes connected to the same bus cannot transmit data during this time. Further, in the method of adding dummy data, it is necessary to add a function of removing dummy data to all nodes on the same bus, which requires a large change cost.

  In view of the above problems, the present invention provides a technique for relaying a part of a transmission path of a bus network that returns a response in a predetermined time while reducing the occurrence of retries and suppressing the cost of changing an existing node. The purpose is to do.

A communication system according to the present invention that achieves the above object is as follows.
A first terminal connected to the bus network; a second terminal connected to another bus network; and a relay device that relays communication between the first terminal and the second terminal. A communication system,
The first terminal is
Dummy data adding means for adding dummy data to data to be transmitted;
Dummy data addition control means for controlling the dummy data addition means so as to add the dummy data to the data transmitted through the relay device,
The second terminal is
Response means for responding in a predetermined time after receiving data from the first terminal;
The relay device is
It is characterized by comprising dummy data removing means for removing the dummy data added to data transmitted from the first terminal to the second terminal and performing relay.

  According to the present invention, it is possible to relay a part of a transmission line of a bus network that returns a response in a predetermined time while reducing the occurrence of retries and suppressing the cost of changing an existing node.

The figure showing the whole structure of a robot control system. The figure showing the internal structure of a robot control system. The figure showing the structure of the data exchanged between nodes. The figure showing the relationship between a message and a response. The figure showing the internal structure of the whole control part 101. FIG. The figure showing the internal structure of the robot control system when carrying out wireless relay. The figure showing the internal structure of the whole control part 601 when carrying out a radio relay. The figure explaining operation | movement of the dummy data addition part 701. FIG. The figure showing the internal structure of the radio relay apparatus 600. The figure showing a mode that a message is relayed by the wireless relay apparatus. The figure which summarized the content of the communication which generate | occur | produces between each node. The figure showing the information which dummy data addition control part 702 holds. The figure showing the detail of operation | movement of the dummy data removal part 902. FIG. The figure showing the internal structure of the radio relay apparatus 600 in 2nd embodiment. The figure showing the connection information which the connection information holding part 1401 hold | maintains.

(First embodiment)
First, an overall configuration of a robot control system as a communication system to which the present invention can be applied will be described with reference to FIG. The overall control unit 101 controls the arm 100 and the hand 110 attached to the end thereof to perform predetermined processing on the processing target 120. The arm 100 has a plurality of joints such as a joint 102 and a joint 103. The joint 102 at the base of the arm 100 is a joint for adjusting the inclination of the entire arm 100, and the joint 103 is a joint for rotating the hand 110. The hand 110 includes a hand control unit 111 and fingers having a plurality of finger joints such as the finger joint 112. The hand control unit 111 will be described later. The finger joint 112 is a joint for adjusting the bending angle of the finger.

  Next, an internal configuration of a robot control system to which the present invention can be applied will be described with reference to FIG. The joint 102 includes a joint control unit 202, a motor 221, and an encoder 222. The motor 221 generates a force that bends the joint 102. The encoder 222 detects the current bending angle of the joint 102.

  The joint control unit 202 generates a force for bending the joint 102 to the instructed angle by controlling the motor 221 while repeatedly acquiring the current bending angle of the joint 102 from the encoder 222. When the angle acquired from the encoder 222 matches the predetermined angle, the joint control unit 202 stops the motor 221 and fixes the joint 102 at that angle. The joint 103 and the finger joint 112 each have a motor and an encoder, and perform the same control as the joint control unit 202.

  Here, the operation of the robot control system will be described using an example in which the workpiece 120 is gripped and moved to another position.

  The overall control unit 101 notifies the joint control unit 202 of the target angle of the joint 102, thereby instructing the joint 102 to bend to that angle. The joint control unit 202 notifies the overall control unit 101 of the completion of the operation when the joint 102 reaches the target angle. When notified of the completion of the operation from the joint control unit 202, the overall control unit 101 notifies the joint control unit 202 of the next target angle. The overall control unit 101 operates such that the arm 100 is operated by repeating such communication with the joint 102 and the joint 103 so as to control the hand 110 so as to have a position and an angle at which the hand 110 can be gripped. Information on the target angle is set in advance in a ROM or the like in the overall control unit 101.

  The hand control unit 111 performs the same communication with the finger joint control unit 212 as between the overall control unit 101 and the joint control unit 202. As a result, the finger of the hand 110 is controlled to control the workpiece 120 to be gripped.

  When the hand 110 comes close to the workpiece 120, the overall control unit 101 gives an instruction “hold” to the hand control unit 111. In response to this, the hand control unit 111 controls the finger joint control unit 212 of the finger joint 112 and other finger joints to perform an operation of gripping the workpiece 120. When the gripping operation is completed, the hand control unit 111 notifies the overall control unit 101 of the operation completion. Thereafter, the overall control unit 101 controls each joint of the arm 100 to move the hand 110 to a predetermined position, and gives an instruction “release” to the hand control unit 111. In response to this, the hand control unit 111 executes an operation of controlling the finger joint control unit 212 and other finger joints to release the workpiece 120.

  Through the control as described above, the workpiece 120 can be gripped and moved to another position. Here, instructions and responses necessary for control are performed via the wired transmission path 200. The overall control unit 101, the joint control unit 202, the joint control unit 203, the hand control unit 111, and the finger joint control unit 212 are nodes connected to the transmission path 200. These nodes and the transmission line 200 constitute one bus network.

  With reference to FIG. 11, a table 1100 showing communication contents occurring between these nodes will be described. In table 1100, each row represents a transmitting node and each column represents a receiving node. For example, a column 1101 indicates that an instruction for a target angle is transmitted from the overall control unit 101 that is a transmission node to the joint control unit 202 that is a reception node. A blank field indicates that communication does not occur between the corresponding nodes. For example, a column 1102 indicates that data transmission from the joint control unit 202 to the hand control unit 111 does not occur. In the example of FIG. 11, the overall control unit 101 transmits a target angle instruction to the joint control unit 202 and the joint control unit 203, and transmits a grip / release instruction to the hand control unit 111. The joint control unit 202 and the joint control unit 203 transmit an operation completion notification to the overall control unit 101. The hand control unit 111 transmits an operation completion notification to the overall control unit 101 and transmits a target angle instruction to the finger joint control unit 212. The finger joint control unit 212 transmits an operation completion notification to the hand control unit 111.

  FIG. 3A shows a data structure exchanged between nodes connected to the transmission path 200. The communication protocol between the nodes conforms to a CAN (Controller Area Network) protocol widely used in the field of device control. In FIG. 3A, a data frame 300 is a frame that is a unit of communication performed between the nodes. The data frame 300 includes a message 301 output from the transmission node, a response 302 output from the reception node, and a CRC delimiter therebetween.

  The message 301 has a header, a payload, and a CRC (Cyclic Redundancy Check). The header includes at least an SOF (Start Of Frame) representing the beginning of the data frame, an ID representing the type of data, and a data length representing the number of bytes of the payload. The ID has a fixed length of 11 bits. In this embodiment, 8 bits out of 11 bits are used as the destination address.

  The destination address is information indicating to which node the data frame 300 is addressed. Each node connected to the transmission line 200 has an address represented by a unique numerical value that does not overlap with other nodes on the same bus. For example, the address of the overall control unit 101 is “101” as shown in FIG. 2, and the address of the joint control unit 202 is “202”. For example, when the destination address of the received message frame is “202”, the joint control unit 202 determines that the message frame is addressed to itself and processes the received data. Of the 11-bit ID, 8 bits are used as the destination address, but the remaining 3 bits are unused. Unused bits are set to 0.

  The payload stores data indicating the content notified from the transmission node to the reception node. For example, the target angle of the joint 102 is notified from the overall control unit 101 to the joint control unit 202. At this time, an identifier indicating that the content of the payload is angle information and a numerical value of the angle are stored in the payload. The The length of the payload is variable.

  CRC is information for error detection. The CRC stores a 15-bit value calculated from each bit of the header and payload. The receiving node calculates a CRC value from the header and payload of the received message, and determines that it has been received correctly if the value matches the CRC included in the received message.

  The response 302 is a response output by the receiving node, and has 9-bit information including a 1-bit ACK slot, a 1-bit ACK delimiter, and a 7-bit EOF (End Of Frame). When the CRC of the received data frame is correct, that is, in the case of ACK, the receiving node transmits the ACK slot as 0 and EOF as all 1. When the CRC of the received data frame is different, that is, in the case of NACK, the receiving node transmits the ACK slot as 1, and the higher 6 bits of EOF as 0. The ACK delimiter is always 1 and fixed. FIG. 3B shows a table 310 that summarizes these. Table 310 is a table in which the value of the 9-bit response output by the receiving node is expressed in binary. That is, the response 302 can be used as delivery confirmation information to the transmission source.

  There is a one-bit free time between the message 301 output from the transmission node and the response 302 output from the reception node. This section is called a CRC delimiter. FIG. 4 shows the relationship between messages and responses in the data frame. When receiving the message 301 from the transmitting node, the receiving node must start transmitting the response 302 after time T1 from the end of the message 301. T1 is a time corresponding to the CRC delimiter, that is, one bit. For example, if the bit rate is 1 megabit per second, T1 is 1 microsecond.

  FIG. 5 shows the internal configuration of the overall control unit 101. The overall control unit 101 includes a reception unit 501, an error detection unit 502, a reception data processing unit 503, a transmission data generation unit 504, and a transmission unit 505.

  The receiving unit 501 detects a data frame on the transmission path 200. The error detection unit 502 confirms the CRC value of the message detected by the reception unit 501 to determine ACK or NACK, and instructs the transmission unit 505 to output a response at the timing shown in FIG. However, no response is output for the data frame from which the station outputs a message. When the destination address of the header of the message received by the receiving unit 501 matches the local address, the received data processing unit 503 analyzes the contents of the payload and performs processing. For example, when the reception unit 501 receives a message having a payload indicating that the target angle has been reached from the joint control unit 202, the reception data processing unit 503 transmits the transmission data so as to transmit the next target position to the joint control unit 202. The generation unit 504 is controlled. The transmission data generation unit 504 generates a message 301 in the format of FIG. 3 based on an instruction from the reception data processing unit 503 and outputs the message 301 to the transmission unit 505. The transmission unit 505 outputs the response instructed from the error detection unit 502 and the message output from the transmission data generation unit 504 to the transmission line 200.

  The internal control unit 101 is different from the internal control unit 202, the joint control unit 203, the hand control unit 111, and the finger joint control unit 212 except for the processing contents of the reception data processing unit 503 and the transmission data generation unit 504. It is the same composition as. For example, the reception data processing unit 503 of the joint control unit 202 extracts target angle information and controls the motor 221 in FIG. The transmission data generation unit 504 acquires the current angle information from the encoder 222 of FIG. 2, and generates a message in which information indicating that the target has been reached is stored in the payload when it matches the last received target angle information.

  Next, in the robot control system described above, a configuration when wirelessly relaying between the arm 100 and the hand 110 in FIG. 1 will be described.

  FIG. 6 shows the internal configuration of the robot control system when wirelessly relaying between the arm 100 and the hand 110. The difference from FIG. 2 in the case where wireless relay is not performed is that the wireless relay device 600 and the wireless relay device 610 are provided in the middle of the wired transmission path 200, and the overall control unit 101 and the hand control unit 111 are all The point is that the control unit 601 and the hand control unit 611 are replaced. The wireless relay device 600 and the wireless relay device 610 relay and transmit data flowing through the transmission path 200 between the arm 100 and the hand 110 by wireless communication.

  Further, in the bus network divided by the wireless relay device 600 and the wireless relay device 610, the side to which the wireless relay device 600 belongs is defined as cluster C0, and the side to which the wireless relay device 610 belongs is defined as cluster C1.

  In the following description, there are places where the addresses of the overall control unit 601 and the hand control unit 611 are referred to. The overall control unit 601 has the same address “101” as the overall control unit 101, and the hand control unit 611 has the same address “111” as the hand control unit 111.

  FIG. 7 shows the internal configuration of the overall control unit 601. A difference from the overall control unit 101 described in FIG. 5 is that the overall control unit 601 further includes a dummy data addition unit 701 and a dummy data addition control unit 702. The operation of the dummy data adding unit 701 will be described with reference to FIG. The dummy data adding unit 701 generates a message 801 by adding a header 802, dummy data 803, and CRC 804 to the message 301 generated by the transmission data generating unit 504. In the header 802, 3 bits that are unused and always 0 in the header 810 of the message 301 are dummy data identifiers indicating whether or not dummy data is added. The values of the dummy data identifiers are all 1. The data length stored in the header 802 is set to the payload in the message 801, that is, the number of bytes of the entire message 301. Other configurations of the header 802 are the same as the header 810 of the message 301.

  The dummy data 803 is a bit string having a length specified by the dummy data addition control unit 702. The value of each bit of the dummy data 803 is arbitrary, for example, all 0. The CRC 804 is a 15-bit CRC calculated from the header 802, the message 301, and the dummy data 803.

  The dummy data addition control unit 702 monitors the message generated by the transmission data generation unit 504, and controls the dummy data addition unit 701 so that dummy data is added only when a condition described later is satisfied. Here, the length of the dummy data 803 is determined based on the relay delay time generated between the radio relay apparatus 600 and the radio relay apparatus 610. The method will be described later with reference to FIG.

  Next, conditions for adding dummy data will be described. The dummy data addition control unit 702 of the overall control unit 601 controls the dummy data addition unit 701 so that dummy data is added only when a message is transmitted to a node belonging to a cluster different from the own node. In order to execute this control, the dummy data addition control unit 702 holds information as shown in the table 1200 of FIG. Table 1200 shows to which cluster each node belongs. For example, since the overall control unit 601 has the address “101”, it belongs to the cluster C 0 as shown in the column 1201. The dummy data addition control unit 702 monitors the destination address of the message generated by the transmission data generation unit 504, and checks whether or not the cluster corresponding to the destination address in the table 1200 is the same as the own node. If they are different, the dummy data adding unit 701 is controlled to add dummy data to the message. On the contrary, control is performed so that dummy data is not added if they are the same.

  FIG. 9 shows the internal configuration of the wireless relay device 600. The wireless relay device 600 includes a wired reception unit 901, a dummy data removal unit 902, a wireless transmission unit 903, a wireless reception unit 904, a wired transmission unit 905, a response relay control unit 906, and a response delay control unit 907. Is provided.

  The wired receiving unit 901 samples the data on the transmission line 200 bit by bit and outputs the sampled data to the dummy data removing unit 902 and the response relay control unit 906.

  The dummy data removal unit 902 detects the message 801 in FIG. 8 from the data acquired from the wired reception unit 901, and further outputs the data obtained by deleting the dummy data from the message to the wireless transmission unit 903 in a predetermined size. . Further, the dummy data removing unit 902 discards a message that does not include dummy data.

  Here, the details of the operation of the dummy data removing unit 902 will be described with reference to the flowchart of FIG.

  In step S <b> 1301, the dummy data removing unit 902 determines whether or not the SOF of the header of the message flowing through the transmission path 200 has been detected. If it is determined that the SOF has been detected (S1301; YES), the process proceeds to S1302. On the other hand, if it is determined that the SOF is not detected (S1301; NO), the process waits until it is detected.

  In step S1302, the dummy data removing unit 902 waits until the end of the header is received.

  In step S1303, the dummy data removal unit 902 refers to the dummy data identifier in the header and determines whether or not the current message includes dummy data. If it is determined that there is dummy data (S1303; YES), the process proceeds to S1304. On the other hand, if it is determined that there is no dummy data (S1303; NO), the process is terminated. If dummy data is included, the message has the structure of message 801 in FIG.

  In step S1304, the dummy data removing unit 902 refers to the data length value of the header 802 in FIG. 8 and determines whether the payload in the message 801, that is, the end of the message 301 has been received. If it is determined that the end of the message 301 has been received (S1304; YES), the process proceeds to S1308. On the other hand, if it is determined that the end of the message 301 has not been received yet (S1304; NO), the process proceeds to S1305.

  In step S1305, the dummy data removal unit 902 holds the bit value received from the wired reception unit 901 in the buffer. This buffer exists in the dummy data removal unit 902 and has a predetermined size.

  In step S1306, the dummy data removal unit 902 determines whether the buffer is full. If it is determined that the buffer is full (S1306; YES), the process proceeds to S1307. On the other hand, if it is determined that the buffer is not full (S1306; NO), the process returns to S1304.

  In step S1307, the dummy data removal unit 902 clears the buffer after outputting the buffer contents to the wireless transmission unit 903. Thereafter, the process returns to S1304.

  In step S1308, the dummy data removing unit 902 outputs the buffer contents to the wireless transmission unit 903, clears the buffer contents, and ends the process.

  The wireless transmission unit 903 wirelessly transmits data input from the dummy data removal unit 902 and the response relay control unit 906. The other party of transmission is the other party of the radio relay apparatus 600, that is, the radio relay apparatus 610. At this time, a header for wireless communication is added as necessary so as not to interfere with other wireless communication, and modulation processing or the like is performed.

  The wireless reception unit 904 demodulates a signal received by wireless communication from the wireless relay device 610 and outputs the demodulated signal to the wired transmission unit 905. The wired transmission unit 905 outputs the data received from the wireless reception unit 904 to the transmission path 200.

  The response relay control unit 906 acquires 9 bits appearing across the 1-bit CRC delimiter immediately after the wired transmission unit 905 outputs the message from the wired reception unit 901, and outputs the 9 bits to the wireless transmission unit 903. These 9 bits are a response to the message output from the wired transmission unit 905.

  The response delay control unit 907 detects the CRC delimiter next to the message received by the wired reception unit 901. Here, when the wired transmission unit 905 receives a response from the wireless reception unit 904 at a timing earlier than the CRC delimiter, the wired transmission unit 905 is controlled to output a response immediately after the CRC delimiter. Such a case occurs when the dummy data length determined by the dummy data addition control unit 702 is longer than the relay delay time in the radio relay apparatuses 600 and 610.

  With reference to FIG. 10, a state in which a message including dummy data is relayed by the wireless relay device will be described. The message 801 generated by the transmission node (first terminal) is partially removed by the dummy data removal unit 902 of the wireless relay device 600 on the transmission side, and the message 301 reaches the reception node (second terminal). The response output by the receiving node is relayed by the transmitting and receiving radio relay apparatuses and reaches the transmitting node. In FIG. 10, a header 1001 is a wireless communication header added by the wireless transmission unit 903 of the wireless relay device 600. The payload 1002 is a payload for wireless communication, and the contents are obtained by modulating the contents of one transmission data buffered by the dummy data removing unit 902.

  Here, T2 is a delay time caused by the message 301 being relayed wirelessly. T3 is a delay time caused by the response being relayed wirelessly. T4 is the time required for the transmission node to output dummy data and CRC. Here, when T4 = T2 + T3 holds, the time T1 between the tail of the message 801 and the head of the response matches the length of the CRC delimiter 1 bit. For this reason, the dummy data addition control unit 702 of the transmission node determines the length of the dummy data so that T4 = T2 + T3 holds. For example, suppose T2 is 30 microseconds, T3 is 10 microseconds, and the communication bit rate is 1 megabit per second. Since the CRC is fixed at 15 bits, the dummy data length is 25 bits in order to set T4 = 30 + 10 = 40 microseconds.

  Here, T2 and T3 are times based on physical transmission delay, whereas T4 can be set only by an integer multiple of the bit length. Therefore, when the fraction is not obtained and T4 = T2 + T3 cannot be obtained, the dummy data addition control unit 702 selects T4 such that T4> T2 + T3. Even in the case of T4> T2 + T3, the response delay control unit 907 of the radio relay apparatus 600 on the transmission side can delay the response output timing to adjust T1 to the length of 1 bit.

  The wireless relay device 610 has the same configuration as the wireless relay device 600. However, the wireless relay device 610 is the counterpart of the wireless communication with the wireless relay device 610.

  The difference between the hand control unit 611 and the hand control unit 111 is the same as the difference between the overall control unit 601 and the overall control unit 101. That is, the hand control unit 611 is obtained by adding a dummy data addition unit 701 and a dummy data addition control unit 702 to the hand control unit 111.

  With the configuration as described above, even when a message is transmitted from the overall control unit 601 to the hand control unit 611 beyond the radio relay device 600 and the radio relay device 610, the response of the hand control unit 611 is determined according to the protocol. Can be returned after T1. The same applies when a message is transmitted from the hand control unit 611 to the overall control unit 601 beyond the radio relay device 600 and the radio relay device 610.

  By the way, when the joint control unit 202 transmits a message to the hand control unit 111 and the finger joint control unit 212, the joint control unit 202 needs to pass through the wireless relay device 600 and the wireless relay device 610. However, as shown in Table 1100 of FIG. 11, the joint control unit 202 has no opportunity to transmit a message to the hand control unit 111 and the finger joint control unit 212. Such a node does not need to include the dummy data addition unit 701 and the dummy data addition control unit 702, and the configuration of FIG. Similarly, the configuration of the joint control unit 203 and the finger joint control unit 212 may be the configuration shown in FIG.

  Here, the message 801 addressed from the overall control unit 601 to the hand control unit 611 is also received by the joint control unit 202 and the joint control unit 203 connected to the same transmission path 200. Since the message 801 is also in the correct format as the protocol like the message 301 in FIG. 3, it does not affect the operation of the joint control unit 202 such that communication cannot be performed. In other words, the joint control unit 202 that does not need to transmit a message beyond the wireless relay device 600 and the wireless relay device 610 operates as usual without adding any changes when the wireless relay devices 600 and 610 are added. To do. The same applies to the joint control unit 203 and the finger joint control unit 212.

  Therefore, according to the present embodiment, the robot control system operating with the configuration of FIG. 2 can be operated with the configuration of FIG. 6 only by adding the dummy data addition function to the overall control unit and the hand control unit. it can. Since the communication between the arm and the hand can be relayed by wireless communication with only such a small change, the following effects by the wireless relay can be obtained at low cost. First, since control errors due to wiring deflection and weight are reduced, the operation accuracy can be improved. Furthermore, by not passing the wiring through the movable part, the life of the wiring can be improved and the cost for maintenance can be reduced. In addition, there is no operational limitation due to the twisting of the wiring of the movable part, and the work throughput can be improved.

  In the present embodiment, the configuration has been described in which each node connected to the transmission path 200 performs communication according to the CAN communication protocol. However, the present invention can also be applied to communication protocols other than CAN. . For example, the response delay control unit 907 detects the end of the message instead of detecting the CRC delimiter. In this way, the present invention can also be applied when each node connected to the transmission line 200 communicates with a communication protocol that returns a response to the received message within a predetermined time. Further, the response returned by the receiving node may be information other than the delivery confirmation. For example, when the joint control unit 202 receives a target angle instruction message, the present invention can be applied even if it is configured to return the current bending angle information of the joint as a response.

(Second Embodiment)
The second embodiment is different from the first embodiment in the internal configuration of the wireless relay device 600 and the wireless relay device 610, and the operation of the dummy data addition control unit 702 of the overall control unit 601 and the hand control unit 611 is different. Except for this, it is the same as the first embodiment. Only the differences will be described below.

  FIG. 14 shows the internal configuration of the wireless relay device 600. Note that the internal configuration of the wireless relay device 610 is the same as that of the wireless relay device 600. The connection information holding unit 1401 holds the address of a node belonging to the same cluster as the own station as connection information. The connection information held by the connection information holding unit 1401 of the wireless relay device 600 is shown in a table 1501 in FIG. In FIG. 6, nodes belonging to the same cluster as the wireless relay device 600 are nodes with addresses “101”, “202”, and “203”. Further, the cluster of the wireless relay device 600 is defined as the cluster C0. A table 1501 represents such connection information. Similarly, the connection information holding unit 1401 of the wireless relay device 610 has connection information as shown in Table 1502.

  These connection information may be set in the connection information holding unit 1401 by the user after determining where to connect the wireless relay device 600 and the wireless relay device 610 in the transmission line 200, or automatically by communication during initial communication. It may be generated. For example, the connection information holding unit 1401 controls the wired transmission unit 905 to transmit a connection confirmation message with an empty payload in order of destination addresses “0”, “1”, and “2” during initial communication, and determines whether there is a response. Check. The node having the destination address when there is a response exists in the same cluster as the own node. In this way, the connection information holding unit 1401 can also obtain connection information as shown in Table 1501 or Table 1502.

  The wireless relay device 600 and the wireless relay device 610 exchange information held by each connection information holding unit 1401 by wireless communication to obtain information as shown in Table 1503. A table 1503 is obtained by merging the table 1501 and the table 1502.

  The relay time storage unit 1402 holds information on the relay delay time when data is relayed between the wireless relay device 600 and the wireless relay device 610. Specifically, this time is the sum of T2 and T3 in FIG. 10, and is a known value. The dummy data addition condition generation unit 1403 uses the information in the table 1503 held by the connection information holding unit 1401 and the relay delay time held by the relay time storage unit 1402 as the dummy data addition condition. Furthermore, the dummy data addition condition generation unit 1403 generates a message including the generated dummy data addition condition, and controls the wired transmission unit 905 so as to transmit the node address belonging to the same cluster as the own station as a destination. In determining the transmission destination, the dummy data addition condition generation unit 1403 of the wireless relay device 600 uses the information in the table 1501. Similarly, the dummy data addition condition generation unit 1403 of the wireless relay device 610 uses the information in the table 1502 to determine the transmission destination of the message including the dummy data addition condition.

  Here, the dummy data addition control unit 702 of the overall control unit 601 and the hand control unit 611 holds information in Table 1510 as an initial value in place of the information in Table 1200 in the second embodiment. When the dummy data addition control unit 702 receives a message including the dummy data addition condition, the dummy data addition control unit 702 rewrites the information in the table 1510 held therein to the condition included in the message. In the configuration of FIG. 6, the information in the table 1503 is transmitted, so the table 1510 is rewritten with the contents of the table 1503. The dummy data addition control unit 702 determines the length of the dummy data from the relay delay time T2 + T3 included in the message including the dummy data addition condition in the same procedure as in the first embodiment.

  The joint control unit 202, the joint control unit 203, and the finger joint control unit 212 do not have the dummy data addition control unit 702. Therefore, no special processing is performed even if a message including dummy data addition conditions is received.

  Here, a case will be considered in which the wireless relay device 600 and the wireless relay device 610 are removed and the configuration is such that all nodes are connected to one transmission line 200. At this time, the dummy data addition control unit 702 determines whether or not to add dummy data based on the information in Table 1510. In Table 1510, since all nodes belong to the same cluster, dummy data is not added. On the other hand, when relaying is performed by the wireless relay device 600 and the wireless relay device 610, the dummy data addition control unit 702 determines whether or not to add dummy data based on the information in the table 1503. In this case, for example, when a message is transmitted from the overall control unit 601 to the hand control unit 611, dummy data is added.

  That is, according to the second embodiment, the same overall control unit 601 can be used when the wireless relay device 600 and the wireless relay device 610 are used and when not used. Further, even when the position where the wireless relay device 600 and the wireless relay device 610 are inserted is changed, or when the cluster configuration changes due to increase or decrease of the nodes, the table 1503 is set according to the cluster configuration. For this reason, the same overall control unit 601 can be used regardless of the presence / absence of wireless relay and the cluster configuration. The same can be said for the hand control unit 611. Therefore, it is not necessary to change the processing of the node connected to the transmission path 200 every time the presence / absence of the wireless relay or the cluster configuration is changed, and the work cost for the wireless relay can be reduced.

(Other embodiments)
The present invention can also be realized by executing the following processing. That is, software (program) that realizes the functions of the above-described embodiments is supplied to a system or apparatus via a network or various storage media, and a computer (or CPU, MPU, or the like) of the system or apparatus reads the program. It is a process to be executed.

Claims (11)

A first terminal connected to the bus network; a second terminal connected to another bus network; and a relay device that relays communication between the first terminal and the second terminal. A communication system,
The first terminal is
Dummy data adding means for adding dummy data to data to be transmitted;
Dummy data addition control means for controlling the dummy data addition means so as to add the dummy data to the data transmitted through the relay device,
The second terminal is
Response means for responding in a predetermined time after receiving data from the first terminal;
The relay device is
A communication system comprising dummy data removing means for removing the dummy data added to data transmitted from the first terminal to the second terminal and performing relaying.   The dummy data adding means determines the length of the dummy data based on a relay delay time required for the relay device to relay data, and adds the dummy data. The communication system described.   The communication system according to claim 1, wherein the response unit responds with delivery confirmation information for notifying a transmission source whether or not data has been correctly received.   The communication system according to any one of claims 1 to 3, wherein the dummy data adding means adds information indicating presence / absence of dummy data addition to the data to be transmitted.   The communication system according to claim 4, wherein the relay device does not relay data to which the dummy data is not added. A communication device connected to a bus network,
Dummy data adding means for adding dummy data to data to be transmitted;
Dummy data addition control means for controlling the dummy data adding means so as to add the dummy data to data transmitted via a relay device to another communication device connected to another bus type network;
A communication apparatus comprising: A relay device that relays data transmitted from a first terminal connected to a bus network to a second terminal connected to another bus network,
A relay apparatus comprising dummy data removing means for removing dummy data added to the data by the first terminal and relaying the dummy data. A method for controlling a communication device connected to a bus network,
A dummy data adding step for adding dummy data to the data to be transmitted;
A dummy data addition control step for controlling to add the dummy data to the data transmitted via the relay device to another communication device connected to another bus type network;
A method for controlling a communication apparatus, comprising: A control method for a relay device that relays data transmitted from a first terminal connected to a bus network to a second terminal connected to another bus network,
A method for controlling a relay apparatus, comprising: a dummy data removing step of performing relay by removing dummy data added to the data by the first terminal.   The program for making a computer perform each process of the control method of the communication apparatus of Claim 8.   The program for making a computer perform the process of the control method of the relay apparatus of Claim 9.

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