Communication systems and robots

Abstract

The present invention provides a communication system (70) that can collect information useful for determining whether the cause of a failure is a cable obstruction or a failure of the lower control unit when there is no response from the lower control unit (71-75). The system includes a main control unit (50), a plurality of lower control units (71-75), and lower power switches (52, 71b-75b) for individually switching the power supply to each lower control unit (71-75). When communication between two control units communicating with each other in an arranged order fails, a confirmation process is performed to confirm whether there is an abnormality in the communication function of the upper control unit while switching the power supply to the lower control unit of the two control units.

Description

Technical Field

[0001] The present invention relates to a communication system and a robot comprising the communication system. Background Art

[0002] Conventionally, a communication system is known that performs communication between a plurality of devices daisy-chained to each other via cables, the system including a top device that is at the top of the arrangement order among the plurality of devices, and a plurality of lower devices that are not at the top of the arrangement order.

[0003] For example, a network system as a communication system described in Patent Document 1 includes a master device as a top-level device and a plurality of slave devices as lower-level devices. The master device and the plurality of slave devices communicate with each other in a daisy-chain connection.

[0004] [Prior art literature]

[0005] [Patent Document]

[0006] Patent Document 1: Japanese Patent Application Laid-Open No. 2013-192012 Summary of the Invention

[0007] Technical problem to be solved by the invention

[0008] In such a network system, when there is no response from a slave device, there is a problem in that it is impossible to determine whether the cause is a cable failure or a failure of the slave device.

[0009] The present invention has been made in view of the above background, and its object is to provide a communication system and a robot as follows: That is, a communication system that can collect information useful for determining whether the cause is a cable failure or a failure of the lower device when there is no response from the lower device.

[0010] Technical means for solving technical problems

[0011] In order to achieve the above-mentioned purpose, one embodiment of the present invention is a communication system that communicates between multiple devices that are daisy-chained with each other via cables, including: a top-level device, which is a device that is at the top of the multiple devices in the arrangement order; and multiple lower-level devices, which are devices that are not at the top in the arrangement order. The communication system includes a power on / off unit that individually turns on and off the power supply to each lower-level device. When communication between two devices that communicate with each other adjacent to each other in the arrangement order fails, a confirmation process is performed. The confirmation process confirms whether there is any abnormality in the communication function of the upper-level device when the power supply to the lower-level device of the two devices is cut off.

[0012] Effects of the Invention

[0013] According to the present invention, there is an excellent effect that, when there is no response from a lower-level device, information useful for determining whether the cause is a cable failure or a failure of the lower-level device can be collected. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 It is a diagram showing the structure of a robot according to an embodiment.

[0015] Figure 2 This is an electrical block diagram showing a control system, a monitoring signal generating unit, each driving unit, and five A / D converters mounted on the robot.

[0016] Figure 3 This is an electrical block diagram showing a main control unit, a first lower control unit, a second lower control unit, a third lower control unit, a fourth lower control unit, and a fifth lower control unit in the control system of the robot.

[0017] Figure 4 This is a flowchart showing the flow of monitoring processing executed by the main control unit of the robot of Example 1.

[0018] Figure 5 This is a flowchart showing the flow of processing in the initial program processing executed by the CPU of the main control unit of the robot together with the flow of processing performed by the lower control units.

[0019] Figure 6 This is a flowchart showing the processing flow in the initial program processing executed by the CPU of the main control unit of the robot of Example 2, together with the processing flow implemented by the lower control unit. DETAILED DESCRIPTION

[0020] Hereinafter, an embodiment of a robot equipped with a communication system according to an embodiment of the present invention will be described with reference to the accompanying drawings. In the following drawings, the actual structure and the scale and number of components may be different to facilitate understanding of the components.

[0021] First, the basic structure of the robot according to the embodiment will be described. Figure 1 This figure shows the structure of a robot 1 according to an embodiment. In this robot 1, multiple arms are mounted in combination on a main body (base) 10, and desired motions are achieved by controlling the motion of each arm. A common arm 11 is mounted on the main body 10. Arms 14 and 15 are mounted on the common arm 11 via connecting arms 12 and 13, respectively.

[0022] The common arm 11 held by the main body 10 is driven to rotate about the rotation axis A1. The arm 14 held by the connecting arm 12 is driven to rotate about the rotation axis A2. The arm 15 held by the connecting arm 13 is driven to rotate about the rotation axis A3.

[0023] A mechanical mechanism for driving the common arm 11 is provided on the main body 10. The rotation axis A1 becomes the axis of the entire robot 1. Therefore, since all components connected to the common arm 11, including the arm 14 and the arm 15, are driven, the load when driving the common arm 11 becomes particularly large. In order to be able to withstand this load, a first drive unit 21 and a second drive unit 22 are provided. The common arm 11 is driven centered on the rotation axis A1 by the first drive unit 21 driving the rotation axis A11 and the second drive unit 22 driving the rotation axis A12. The drive of the rotation axis A11 and the drive of the rotation axis A12 are converted into the drive of the rotation axis A1 by the third drive unit 23. That is, the drive of the rotation axis A1 is directly performed by the third drive unit 23.

[0024] The connecting arm 12 holds the fourth drive unit 24. The fourth drive unit 24 includes a mechanical mechanism for driving the arm 14. Furthermore, the connecting arm 13 holds the fifth drive unit 25. The fifth drive unit 25 includes a mechanical mechanism for driving the arm 15. The fourth drive unit 24 and the fifth drive unit 25 each include a motor, gears, bearings, etc. The first drive unit 21 and the second drive unit 22 also each include a motor, gears, bearings, etc. The third drive unit 23 includes gears, bearings, etc. for converting the drive of the rotational axes A11 and A12 into the drive of the rotational axis A1.

[0025] The robot 1 includes a communication system 70 for controlling the motions of the common arm 11, the arm 14, and the arm 15 by driving the first drive unit 21, the second drive unit 22, the third drive unit 23, the fourth drive unit, and the fifth drive unit 25. The communication system 70 as a communication system includes a CPU and the like. Figure 1 In the illustrated example, the communication system 70 is disposed in the main body (base) 10 , but may be disposed separately from the robot 1 , for example, at a location remote from the robot 1 .

[0026] The first drive unit 21, the second drive unit 22, the third drive unit 23, the fourth drive unit 24, and the fifth drive unit 25 are the main parts that are subject to wear and tear or deterioration over time as the robot 1 works. The robot 1 is equipped with five sensors 30, each of which detects a predetermined characteristic for predicting failures of these drive units. Each sensor 30 is composed of, for example, an acceleration sensor for detecting vibrations generated in the drive unit. The sensor 30 is fixed to the part of the drive unit that detects vibrations. Since the size and weight of the sensor 30 are negligible compared to the above-mentioned parts, the vibration (acceleration) detected by the sensor 30 becomes a value related to the acceleration applied to the above-mentioned parts. A DC voltage of a value corresponding to the magnitude of the vibration is output from the sensor 30 as an analog signal.

[0027] Figure 2 This is an electrical block diagram showing the communication system 70, the monitoring signal generating unit 40, the driving units (21 to 25), and the five A / D converters 31 mounted on the robot 1. In this figure, the area within the dotted line corresponds to the interior of the robot 1.

[0028] The communication system 70 includes a main control unit 50 as the highest-level device, a first lower-level control unit 71 as a lower-level device, a second lower-level control unit 72 as a lower-level device, a third lower-level control unit 73 as a lower-level device, a fourth lower-level control unit 74 as a lower-level device, and a fifth lower-level control unit 75 as a lower-level device. Hereinafter, the first lower-level control unit 71, the second lower-level control unit 72, the third lower-level control unit 73, the fourth lower-level control unit 74, and the fifth lower-level control unit 75 are collectively referred to as the lower-level control units.

[0029] The main control unit 50 and the lower-level control units communicate with each other via daisy-chain cables C1 to C5. The main control unit 50 is the highest-level device, located at the top of the hierarchy of the main control unit 50 and the lower-level control units. Hereinafter, regarding the positional relationship of the lower-level control units, the position closer to the main control unit 50 is referred to as the upper level, and the position farther from the main control unit 50 is referred to as the lower level. Among the lower-level control units, the first lower-level control unit 71, the second lower-level control unit 72, the third lower-level control unit 73, the fourth lower-level control unit 74, and the fifth lower-level control unit 75 are located at the upper level in this order.

[0030] The robot 1 includes five A / D converters 31. Each A / D converter 31 is connected to a different lower-level control unit (71 to 75). The analog signal G1 output from the sensor 30 of the first drive unit 21 is converted into a vibration signal S1 consisting of a digital signal indicating the magnitude of vibration via the A / D converter 31, and then input to the first lower-level control unit 71. The analog signal G2 output from the sensor 30 of the second drive unit 22 is converted into a vibration signal S2 via the A / D converter 31, and then input to the second lower-level control unit 72. The analog signal G3 output from the sensor 30 of the third drive unit 23 is converted into a vibration signal S3 via the A / D converter 31, and then input to the third lower-level control unit 73. The analog signal G4 output from the sensor 30 of the fourth drive unit 24 is converted into a vibration signal S4 via the A / D converter 31, and then input to the fourth lower-level control unit 74. The analog signal G5 output from the sensor 30 of the fifth drive unit 25 is converted into a vibration signal S5 via the A / D converter 31 , and then input to the fifth lower control unit 75 .

[0031] The electrical connection between the sensor 30 and the A / D converter 31 can be made using, for example, a coaxial cable that easily suppresses noise intrusion. If the A / D converter 31 is provided near the corresponding sensor 30, the length of the coaxial cable can be limited to a length that is negligible compared to the overall length of the robot 1.

[0032] The fifth lower control unit 75 transmits the vibration signal S5 to the main control unit 50 via the fourth lower control unit 74, the third lower control unit 73, the second lower control unit 72, and the first lower control unit 71. The fourth lower control unit 74 transmits the vibration signal S4 to the main control unit 50 via the third lower control unit 73, the second lower control unit 72, and the first lower control unit 71. The third lower control unit 73 transmits the vibration signal S3 to the main control unit 50 via the second lower control unit 72 and the first lower control unit 71. The second lower control unit 72 transmits the vibration signal S2 to the main control unit 50 via the first lower control unit 71. The first lower control unit 71 transmits the vibration signal S1 to the main control unit 50. The main control unit 50 transmits each vibration signal (S1 to S5) to the monitoring signal generation unit 40. The monitoring signal generating unit 40 divides each vibration signal ( S1 to S5 ) into time series, converts the divided signals into serial data, and outputs the serial data to the outside of the robot 1 as the monitoring signal S0 .

[0033] The monitoring device 100 receives the monitoring signal S0 via the connectors CN1 (CN11, CN12) on the robot 1, a single external cable C, and the connectors CN2 (CN21, CN22) on the monitoring device 100. The monitoring device 100 can identify and store the output values ​​from each sensor 30 by receiving the signal.

[0034] Figure 3 This is an electrical block diagram illustrating the main control unit 50, first lower-level control unit 71, second lower-level control unit 72, third lower-level control unit 73, fourth lower-level control unit 74, and fifth lower-level control unit 75 of the communication system 70. The main control unit 50 includes a CPU (Central Processing Unit) 51, a lower-level power switch 52, a communication driver 53, and a lower-level power supply 54. The lower-level power supply 54 outputs power to each lower-level control unit and is connected to the lower-level power switch 52. The lower-level power switch 52 is a switch for turning the power supply to the first lower-level control unit 71 on and off. It is in the "off" state when it does not receive a power-on command signal from the CPU 51. The CPU 51 switches the lower-level power switch 52 to the "on" state by outputting a power-on command signal to the lower-level power switch 52, thereby supplying power to the first lower-level control unit 71. The CPU 51 of the main control unit 50 can communicate with the CPU 71 a of the first lower control unit 71 via the communication driver 53 , the cable A ( C1 ), and a higher-level communication driver 71 c of the first lower control unit 71 described later.

[0035] The main control unit 50 and the first lower control unit 71 are connected to each other by a cable A (C1) including at least four lines including a power line Vcc, a ground line GND, a first data line D+, and a second data line D−, and communicate with each other via the cable A (C1).

[0036] The first lower control unit 71 includes a CPU 71a, a lower power switch 71b, an upper communication driver 71c, a lower communication driver 71d, a communication switching switch 71e, an ammeter / voltmeter 71f, etc. The lower power switch 71b is a switch for turning on and off the power supply to the second lower control unit 72, and is in an "off" state when it does not receive a power-on command signal output from the CPU 71a. The CPU 71a outputs a power-on command signal to the lower power switch 71b, thereby enabling the lower power switch 71b to be in an "on" state and supplying power to the second lower control unit 72. The main control unit 50 controls the first drive unit ( Figure 2 In addition, the CPU 71a of the first lower control unit 71 can communicate with the lower side communication driver 71d, the cable ( Figure 2The communication switch 71e switches between connecting the transmit terminal Tx1 of the CPU 71a to the transmit element of the upper-side communication driver 71c and connecting the receive element of the lower-side communication driver 71d to the transmit element of the upper-side communication driver 71c. The current / voltage meter 71f measures the power supply current flowing through the first lower-level control unit 71 and the power supply voltage applied to the first lower-level control unit 71, and transmits the results to the CPU 71a.

[0037] The CPU 71a, serving as the controller of the first lower-level control unit 71, includes zeroth to fifth internal switches (SW0-SW5), a transmit terminal Tx1, a first receive terminal Rx1, and a second receive terminal Rx2. When the zeroth internal switch SW0 of the CPU 71a is turned on, the output from the zeroth internal switch SW0 is turned on, and the lower-level power supply switch 71b is turned on. When the first internal switch SW1 of the CPU 71a is turned on, signals can be output from the upper-level communication driver 71c. When the second internal switch SW2 of the CPU 71a is turned on, signals can be received by the upper-level communication driver 71c. When the fourth internal switch SW4 of the CPU 71a is turned on, signals can be output from the lower-level communication driver 71d. When the fifth internal switch SW5 of the CPU 71a is turned on, signals can be input from the lower-level communication driver 71d. When the third internal switch SW3 of the CPU 71a is turned on, the communication switching switch 71e connects the transmit terminal Tx1 to the transmit element of the upper-side communication driver 71c. Conversely, when the third internal switch SW3 of the CPU 71a is turned off, the communication switching switch 71e connects the receive element of the lower-side communication driver 71d to the transmit element of the upper-side communication driver 71c. Consequently, the signal output from the receive element of the lower-side communication driver 71d is transmitted to the upper-side via the communication switching switch 71e and the transmit element of the upper-side communication driver 71c.

[0038] Signals received by the upper-side communication driver 71c are transmitted to the CPU 71a via the first receiving terminal Rx1 of the CPU 71a and then to the lower-side communication driver 71d. Signals transmitted from the lower-side are transmitted to the CPU 71a via the lower-side communication driver 71d and the second receiving terminal Rx2. Furthermore, depending on the state of the communication switch 71e, the signal is also transmitted to the upper-side communication driver 71c.

[0039] The second lower control unit 72 , the third lower control unit 73 , the fourth lower control unit 74 , and the fifth lower control unit 75 described later each include similar internal switches ( SW0 to SW5 ), a transmission terminal Tx1 , a first reception terminal Rx1 , and a second reception terminal Rx2 .

[0040] The first lower control unit 71 and the second lower control unit 72 are connected to each other by a cable B (C2) including at least four lines including a power line Vcc, a ground line GND, a first data line D+, and a second data line D−, and communicate with each other via the cable B (C2).

[0041] The second lower control unit 72 includes a CPU 72a, a lower power switch 72b, an upper communication driver 72c, a lower communication driver 72d, a communication switching switch 72e, an ammeter / voltmeter 72f, etc. The lower power switch 72b is a switch for turning on and off the power supply to the third lower control unit 73, and is in an "off" state when it does not receive a power-on command signal output from the CPU 72a. The CPU 72a outputs a power-on command signal to the lower power switch 72b, thereby turning the lower power switch 72b into an "on" state and providing power to the third lower control unit 73. The main control unit 50 controls the second drive unit ( Figure 2 In addition, the CPU 72a of the second lower control unit 72 can communicate with the lower side via the communication driver 72d, the cable ( Figure 2 The communication switch 72e switches between connecting the transmit terminal Tx1 of the CPU 72a to the transmit element of the upper-side communication driver 71c and connecting the receive element of the lower-side communication driver 72d to the transmit element of the upper-side communication driver 72c. The current / voltage meter 72f measures the power supply current flowing through the second lower-level control unit 72 and the power supply voltage applied to the second lower-level control unit 72, and transmits the results to the CPU 72a.

[0042] The second lower control unit 72 and the third lower control unit 73 are connected to each other through a cable C ( C3 ) composed of at least four lines including a power line Vcc, a ground line GND, a first data line D+, and a second data line D−, and communicate with each other via the cable C ( C3 ).

[0043] The third lower control unit 73 includes a CPU 73a, a lower power switch 73b, an upper communication driver 73c, a lower communication driver 73d, a communication switching switch 73e, an ammeter / voltmeter 73f, etc. The lower power switch 73b is a switch for turning on and off the power supply to the fourth lower control unit 74, and is in an "off" state when it does not receive a power-on command signal output from the CPU 73a. The CPU 73a outputs a power-on command signal to the lower power switch 73b, thereby enabling the lower power switch 73b to be in an "on" state and supplying power to the fourth lower control unit 74. The main control unit 50 controls the third drive unit ( Figure 2 In addition, the CPU 73a of the third lower control unit 73 can communicate with the lower side via the communication driver 73d, the cable ( Figure 2 The communication switch 73e switches between connecting the transmit terminal Tx1 of the CPU 73a with the transmit element of the upper-side communication driver 73c, and connecting the receive element of the lower-side communication driver 73d with the transmit element of the upper-side communication driver 73c. ​​The current / voltage meter 73f measures the power supply current flowing through the third lower-level control unit 73 and the power supply voltage applied to the third lower-level control unit 73, and transmits the results to the CPU 73a.

[0044] The third lower control unit 73 and the fourth lower control unit 74 are connected to each other by a cable D (C4) consisting of at least four lines including a power line Vcc, a ground line GND, a first data line D+, and a second data line D−, and communicate with each other via the cable D (C4).

[0045] The fourth lower control unit 74 includes a CPU 74a, a lower power switch 74b, an upper communication driver 74c, a lower communication driver 74d, a communication switching switch 74e, an ammeter / voltmeter 74f, etc. The lower power switch 74b is a switch for turning on and off the power supply to the fifth lower control unit 75, and is in an "off" state when it does not receive a power-on command signal output from the CPU 74a. The CPU 74a can turn the lower power switch 74b to an "on" state by outputting a power-on command signal to the lower power switch 74b, thereby supplying power to the fifth lower control unit 75. The main control unit 50 controls the fourth drive unit ( Figure 2 In addition, the CPU 74a of the fourth lower control unit 74 can communicate with the lower side via the communication driver 74d, the cable ( Figure 2The communication switch 74e switches between connecting the transmit terminal Tx1 of the CPU 74a to the transmit element of the upper-side communication driver 74c and connecting the receive element of the lower-side communication driver 74d to the transmit element of the upper-side communication driver 74c. The current / voltage meter 74f measures the power supply current flowing through the fourth lower-level control unit 74 and the power supply voltage applied to the fourth lower-level control unit 74, and transmits the results to the CPU 74a.

[0046] The fourth lower control unit 74 and the fifth lower control unit 75 are connected to each other by a cable E (C5) consisting of at least four lines including a power line Vcc, a ground line GND, a first data line D+, and a second data line D−, and communicate with each other via the cable E (C5).

[0047] The fifth lower control unit 75 includes a CPU 75a, a lower power switch 75b, an upper-side communication driver 75c, a lower-side communication driver 75d, a communication switching switch 75e, an ammeter / voltage meter 75f, and the like. The lower power switch 75b is a switch for turning on and off the power supply to the lower control unit located below the fifth lower control unit 75, and is in the "off" state when it does not receive the power-on command signal output from the CPU 75a. The CPU 75a outputs a power-on command signal to the lower power switch 75b, causing the lower power switch 75b to be in the "on" state, thereby being able to supply power to the lower control unit located below the fifth lower control unit 75. However, in the illustrated example, no lower control unit is configured below the fifth lower control unit 75. The main control unit 50 controls the fifth drive unit ( Figure 2 25). The communication switch 75e switches between connecting the transmit terminal Tx1 of the CPU 75a and the transmit element of the upper-level communication driver 75c, and connecting the receive element of the lower-level communication driver 75d and the transmit element of the upper-level communication driver 75c. The current / voltage meter 75f measures the power supply current flowing through the fifth lower-level control unit 75 and the power supply voltage applied to the fifth lower-level control unit 75, and transmits the results to the CPU 75a.

[0048] The lower power switch 52 of the main control unit 50 and the lower power switches ( 71 b , 72 , 73 b , 74 b , 75 b ) of each lower control unit function as a power-on stamp stage for individually turning on and off the power supply to each lower device.

[0049] Each lower control unit (71-75) can cause the CPU 71a to receive a signal transmitted from the upper side via the receiving element of the upper-side communication driver (e.g., 71c) and the first receiving terminal Rx1 of the CPU (e.g., 71a). Furthermore, each lower control unit can cause the CPU to receive a signal transmitted from the lower side via the receiving element of the lower-side communication driver (e.g., 71d) and the second receiving terminal Rx2 of the CPU. Furthermore, each lower control unit can transmit a signal transmitted from the CPU's transmitting terminal Tx to the upper side via the transmitting element of the upper-side communication driver.

[0050] In the communication system 70, it is assumed that the communication between the main control unit 50 and the second lower control unit 72 is blocked. In this case, it is difficult to determine whether the communication between the first lower control unit 71 and the second lower control unit 72 is blocked due to a fault in the first lower control unit 71, or whether the communication between the first lower control unit 71 and the second lower control unit 72 is blocked due to a fault in the cable B (C2). The so-called cable failure is specifically a fault caused by a short circuit of at least two of the four wires or a breakage of at least one wire. If such a fault occurs, even if a response request signal is sent from the lower control unit on the upper side to the lower control unit on the lower side, it cannot reach the lower control unit on the lower side normally, so a response signal is not sent from the lower control unit on the lower side, and a response timeout occurs.

[0051] Next, a characteristic configuration of the robot 1 according to the embodiment will be described.

[0052] Assume that the communication between adjacent control units (between the main control unit 50 and the first lower control unit 71, or between two adjacent lower control units) is blocked. In this case, the communication system 70 performs a confirmation process to confirm whether there is any abnormality in the communication function of the upper-level control unit while cutting off the power supply to the lower-level control unit of the two control units. For example, in the case where the communication between the first lower-level control unit 71 and the second lower-level control unit 72 is blocked, the main control unit 50 confirms whether there is any abnormality in the communication function of the first lower-level control unit 71 on the upper side while cutting off the power supply to the second lower-level control unit 72 on the lower side.

[0053] In this configuration, if there is an abnormality in the communication function of the upper-side control unit, the cause of the communication failure can be determined to be a failure of the upper-side control unit, not a failure in the cable connecting the upper-side control unit and the lower-side control unit. In contrast, if there is no abnormality in the communication function of the upper-side control unit, the cause of the communication failure can be determined to be a failure in the cable connecting the upper-side control unit and the lower-side control unit, not a failure in the upper-side control unit. Therefore, according to the robot 1, when there is no response from the lower-side control unit, information useful for determining whether the cause is a cable failure or a failure in the lower-side control unit can be collected.

[0054] Next, each embodiment will be described in which a more characteristic structure is added to the robot 1 of the embodiment. Unless otherwise specified, the structure of the robot 1 of each embodiment is the same as that of the embodiment.

[0055] [Example 1]

[0056] In order to enable normal communication between daisy-chained devices, each lower-level control unit must be assigned a unique identification code. Each lower-level control unit sends various signals along with its unique identification code, allowing the CPU 51 of the main control unit 50 to determine which lower-level control unit the signal is from. In addition, the main control unit 50 sends a signal to any lower-level control unit along with the unique identification code of the lower-level control unit, allowing each lower-level control unit to determine whether the signal is intended for it.

[0057] Each lower-level control unit does not have a unique identification code when it is shipped from the factory. Therefore, it is necessary to assign a unique identification code to each lower-level control unit during initial startup. The identification code assignment process described below is used to assign a unique identification code to each lower-level control unit.

[0058] Figure 4 This is a flowchart showing the process flow of the monitoring process executed by the main control unit 50 of the robot 1 of Example 1. The CPU 51 of the main control unit 50 monitors whether there is a communication error between the control units through this monitoring process. If there is no response signal from any of the five lower control units (71 to 75), the CPU 51 of the main control unit 50 determines that there is a communication error and turns on its own lower power switch ( Figure 3 After the lower power switch of the main control unit 50 is turned off, the initial program processing described below is executed. By turning off the lower power switch of the main control unit 50, the power supply to all lower control units (71 to 75) is stopped, and the lower power switches of all lower control units are turned off.

[0059] Figure 5 This flowchart shows the process flow of the initial program processing executed by the CPU 51 of the main control unit 50, together with the process flow implemented by the lower control units. The initial program processing is executed immediately after the main control unit 50 is initially started, or when a communication error is detected in the monitoring processing described later.

[0060] When the CPU 51 of the main control unit 50 starts the initial program processing, it first turns on its own lower power switch 52 to supply power to the first lower control unit 71. Figure 5 The steps s7 to s20 in FIG. 1 do not represent steps performed only by the first lower control unit 71 , but are steps commonly performed by all lower control units.

[0061] Next, after updating the identification code according to the prescribed rules, the main control unit 50 transmits the updated identification code to the lower-level side (s2). This identification code is used by the first lower-level control unit 71 during initial issuance, and by the second, third, fourth, and fifth lower-level control units (72, 73, 74, and 75) during subsequent issuances. The prescribed rules for updating the identification code include, for example, the following rule: the last three digits of the identification code are numeric, and these three digits are incremented by one each time, starting from the default value "000."

[0062] The lower control unit to which power is supplied (for example, the first lower control unit 71 when the lower power switch of the main control unit 50 is turned on) sets the communication mode to the alternating mode (s8). The alternating mode is a mode in which a transmission mode for transmitting signals and a reception mode for receiving signals are alternately executed. In the transmission mode, only the first internal switch SW1, the third internal switch SW3, and the fifth internal switch SW5 of the first internal switch SW1 to the fifth internal switch SW5 are turned on (become in the on state). In the reception mode, only the second internal switch SW2 and the fourth internal switch SW4 of the first internal switch SW1 to the fifth internal switch SW5 are turned on. In addition, in the transmission mode, when the CPU (for example, 71a) receives a signal transmitted from the lower side via the receiving element of the lower-side communication driver (for example, 71d) and its own second reception terminal Rx2, it transmits the signal from the transmission terminal Tx to the upper side.

[0063] When the lower control unit receives an identification code in receive mode ("Yes" in s9), it stores the identification code in its own storage circuit (s10), and then transmits a storage completion signal in transmit mode (s11). This storage completion signal is combined with the identification code assigned to the lower control unit and transmitted. Subsequently, all identification codes are combined in a signal sent from the lower control unit's CPU to the upper side.

[0064] The lower-level control unit, having transmitted the storage completion signal as described above, sets the communication mode to test mode (s12) to diagnose whether its lower-level communication driver (e.g., 71d) has any faults. In this test mode, five of the CPU's internal switches, SW1 through SW5, excluding the first internal switch SW1, are turned on. By turning on the first internal switch SW1, the fourth internal switch SW4, and the fifth internal switch SW5, the CPU can receive signals transmitted from the upper-level side as follows. Specifically, the CPU can receive signals via the receiving element of the upper-level communication driver (e.g., 71c), the transmitting and receiving elements of the lower-level communication driver, and the second receiving terminal Rx2.

[0065] On the other hand, if the main control unit 50 receives a storage completion signal from the lower control unit ("Yes" in s3), it transmits a test signal in combination with the identification code of the lower control unit being tested (s4). When the lower control unit, which has set its communication mode to test mode as described above, receives the test signal along with its own identification code ("Yes" in S13), it sets its communication mode to alternating mode (s14) and, in transmit mode, transmits an OK signal indicating that there is no abnormality in the lower-side communication driver (s15). Conversely, if the lower control unit does not receive a test signal ("No" in s13), it sets its communication mode to alternating mode (s16) and, in transmit mode, transmits an NG signal indicating that there is an abnormality in the lower-side communication driver (s17). The lower control unit then turns on its own lower power switch (e.g., 71b) to supply power to the lower control unit adjacent to it on the downstream side. The lower control unit thus supplied with power executes the processing flow of s8 to s18 and s19, described later.

[0066] When the main control unit 50 receives a result signal (result OK signal or result NG signal) transmitted from the lower control unit ("YES" in s5), it stores the result signal together with the identification code of the lower control unit that sent the signal in its own storage circuit (s6), and then loops the processing flow back to the above-mentioned s2. Through this loop, a new identification code is transmitted.

[0067] If the main control unit 50, which loops the process back to step s2, does not receive a storage completion signal after a predetermined period of time despite sending an identification code (s2) ("No" in s3), it determines that the assignment of identification codes to all lower-level control units and the testing of the communication functions of the lower-level communication drivers (confirmation of abnormalities) have been completed. The main control unit 50 then transmits a completion signal in combination with the identification code to each of the lower-level control units (s7), terminating the series of processing flows. Furthermore, any lower-level control unit that receives this completion signal ("Yes" in s19) also terminates the series of processing flows.

[0068] In addition, Figure 5 Among them, steps s1 to s3 and s8 to s11 correspond to the identification code assignment process for assigning an identification code to the lower control unit, and steps s4 to s6 and s12 to s18 correspond to the confirmation process for confirming whether there is any abnormality in the communication function of the lower control unit.

[0069] The operator can determine that the cause of the communication failure is the cable (for example, cable B) if the result information stored in the storage circuit of the main control unit 50 is OK, and can determine that the cause is the lower-side communication driver of the lower control unit (for example, 71) if it is NG.

[0070] Furthermore, normal completion of the identification code assignment process means that the first internal switch, the second internal switch, and the upper-side communication driver (for example, 71 c ) of the CPU of the lower-level control unit to which the identification code is assigned are operating normally.

[0071] During the monitoring process, for example, it is assumed that the response from the fourth lower control unit 74 disappears. In this case, if the communication function of the lower-side communication driver 74d of the third lower control unit 73 is determined to be normal on the basis of cutting off the power supply to the fourth lower control unit 74, the following actions can be performed. That is, it is possible to determine which of the lower-side communication driver 74d and the cable C (C3) is the cause of the failure to respond. However, in this case, it is necessary to perform a dedicated control for determining whether the communication function of the third lower control unit 73 is normal. In contrast, in the robot 1 involved in Example 1, regardless of which of the multiple lower control units cannot respond, the initial program processing is executed when the failure to respond is detected. Then, in the initial program processing, it is confirmed whether there is any abnormality in the communication function of the lower-side communication driver in each lower control unit.

[0072] This configuration allows the presence of an abnormality to be confirmed without using a dedicated control program for confirming the presence of an abnormality in the communication function of a lower-level communication driver in a lower-level control unit that is one level higher than the unresponsive lower-level control unit. Therefore, according to the robot 1, a dedicated control program for confirming the presence of an abnormality in the communication function of a lower-level communication driver in a lower-level control unit that is one level higher than the unresponsive lower-level control unit is not required, thereby reducing the information capacity of the control program.

[0073] [Example 2]

[0074] The CPU 51 of the main control unit 50 of the robot 1 of the second embodiment executes Figure 4 The monitoring process shown and Figure 5 Initial program processing shown.

[0075] Figure 6 This is a flowchart showing the processing flow of the initial program processing executed by the CPU 51 of the main control unit 50 of the robot 1 of the second embodiment together with the processing flow executed by the lower control unit. Figure 6 The processing flow shown is only for Figure 5 The differences in the processing flow shown will be described.

[0076] The main control unit 50 sends a predetermined identification code in the process of s2. This identification code is a code assigned to the first lower control unit 71. In addition, after storing the signal of the result information sent from the lower control unit (the result OK signal or the result NG signal) (s7), the main control unit 50 causes the processing flow to loop back to s3 instead of s2. Therefore, the main control unit 50 only sends the initial identification code assigned to the first lower control unit 71 once in the initial program processing. In addition, the main control unit 50 sets the sent flag (s6) after sending the test signal (s5) only when the sent flag described later is not set ("No" in s4). This test signal is a test signal for testing the communication function of the lower-side communication driver 71d of the first lower control unit 71, and is sent in combination with the identification code of the first lower control unit 71. That is, the main control unit 50 only sends the test signal once in the initial program processing.

[0077] In the test mode set in s14, the CPU's five internal switches, SW1 through SW5, are turned on. The CPU in the lower-level control unit, with the communication mode set to the test mode described above, transmits a test signal. This test signal is received by the CPU via the transmit terminal TX, the upper-side communication driver (e.g., 71c), the lower-side communication driver (e.g., 71d), and the second receive terminal Rx2. However, if there is an error in the lower-side communication driver, the CPU will not receive the signal. The lower-level control unit CPU transmits a result signal (a result OK signal or a result NG signal) corresponding to the reception result (s17, s19).

[0078] When the lower control unit turns on its own lower power switch to supply power to the lower control unit on the lower side (s20), it issues and transmits an identification code (s21). This identification code is issued based on the identification code of the lower control unit that issued the identification code.

[0079] The signal is output from the transmission terminal Tx together with the signal (s7). The output signal is received by the main control unit 50 via the upper communication driver (for example, 71c).

[0080] As described above, in the robot according to the second embodiment, the upper-side lower-level control unit of two adjacent lower-level control units issues an identification code of the lower-side lower-level control unit and transmits a test signal to the lower-side lower-level control unit.

[0081] In this configuration, the presence or absence of a failure in the lower-side communication driver (for example, 71d) can be determined by the confirmation process executed by the lower-level control unit including the lower-side communication driver.

[0082] While preferred embodiments and examples of the present invention have been described above, the present invention is not limited to the embodiments and examples, and various modifications and variations are possible within the scope of the gist of the invention. The embodiments and examples are intended to be included within the scope and gist of the invention, as well as within the scope of the invention set forth in the claims and their equivalents.

[0083] The present invention exhibits unique effects through the following aspects.

[0084] [First method]

[0085] The first method is a communication system (such as communication system 70), which communicates between multiple devices daisy-chained to each other via cables, including: a top-level device (such as a main control unit 50), which is a device that is at the top of the multiple devices in the arrangement order; and multiple lower-level devices (such as a first lower-level control unit 71 to a fifth lower-level control unit 75), which are devices that are not at the top in the arrangement order. The communication system is characterized in that it includes a power on / off unit (such as a lower power switch 52, 71b, 72b, 73b, 74b, 75b), which individually turns on and off the power supply to each lower-level device. When communication between two devices that are adjacent to each other in the arrangement order fails, a confirmation process is performed. The confirmation process confirms whether there is any abnormality in the communication function of the upper-side device in the state where the power supply to the lower-side device of the two devices is cut off.

[0086] In the first embodiment, if a communication malfunction occurs in a higher-level device, the cause of the communication failure can be determined to be a failure in the upper-level device, not a problem with the cable connecting the upper-level device and the lower-level device. In contrast, if a communication malfunction does not occur in the higher-level device, the cause of the communication failure can be determined to be a failure in the cable connecting the upper-level device and the lower-level device, not a problem with the upper-level device. Therefore, according to the first embodiment, when there is no response from a lower-level device, information useful for determining whether the cause is a problem with the cable or a failure in the lower-level device can be collected.

[0087] [Second method]

[0088] The second mode is characterized in that, in the communication system of the first mode, each lower device (e.g., the first lower control unit 71 to the fifth lower control unit 75) includes a controller (e.g., CPU 71a to 75a), an upper-side communication driver (e.g., 71c to 75c), and a lower-side communication driver (e.g., 71d to 75d), and the upper-side communication driver sends a signal sent from the controller to the uppermost device or the lower device on the upper side, and sends a signal sent from the uppermost device or the lower device on the upper side to the controller and the lower-side communication driver, and the lower-side communication driver sends a signal to the lower device on the lower side. The controller sends a signal sent from an upper-side communication driver and sends a signal sent from a lower-level device on the lower side to the upper-side communication driver. The controller includes: a first receiving terminal (for example, a first receiving terminal Rx1), which is connected to a receiving line, and the receiving line connects the receiving element of the upper-side communication driver with the sending element of the lower-side communication driver; and a second receiving terminal (for example, a second receiving terminal Rx2), which is connected to a sending line, and the sending line connects the sending element of the upper-side communication driver with the receiving element of the lower-side communication driver.

[0089] According to the second aspect, in each lower device, the controller can receive, via the second receiving terminal, the test signal that has sequentially passed through the transmitting element and the receiving element of the lower-side communication driver.

[0090] [Third Method]

[0091] The third aspect is characterized in that, in the communication system of the second aspect, the confirmation process initiated when communication between two lower devices adjacent to each other in arrangement order becomes unavailable includes a step of sending a test signal from the highest device (e.g., Figure 5 and confirming in the lower device of the upper side of the two lower devices whether the controller receives the test signal received by the upper side communication driver via the lower side communication driver and the second receiving terminal (eg, Figure 5 s13).

[0092] According to the third method, for the test signal sent from the highest-level device, by confirming whether it is received by the controller of the upper-side communication driver, the lower-side communication driver and the second receiving terminal in the lower-level device that becomes the confirmation object, it is possible to confirm whether there is any abnormality in the communication function of the lower-level device.

[0093] [Form 4]

[0094] The fourth mode is characterized in that, in the communication system of the first mode, the confirmation processing started based on the situation where the communication between two lower devices adjacent to each other in the arrangement order becomes unavailable includes: a process of sending a test signal from the lower device adjacent to each other on the upper side to the lower device on the upper side of the two lower devices; and a process of confirming in the lower device on the upper side of the two lower devices whether the controller receives the test signal received by the upper side communication driver via the lower side communication driver and the second receiving terminal.

[0095] According to the fourth aspect, the presence of an abnormality in the lower-side communication driver of the lower device to be checked for communication function can be checked based on a test signal transmitted from the lower device adjacent upstream of the lower device.

[0096] [Fifth Method]

[0097] The fifth mode is characterized in that, in the communication system of the third mode or the fourth mode, the power on / off unit (for example, the lower power switch 52, the lower power switches 71b~75b) is a switch configured in each lower device, and the switch turns on and off the transmission of power sent from the upper side to the lower side.

[0098] According to the fifth aspect, the power supply to each lower-level device can be turned on and off by turning each switch on and off.

[0099] [Sixth Method]

[0100] The sixth mode is characterized in that, in the communication system of the fifth mode, the controller of each lower device includes a communication switching switch, which switches the connection state between the state of connecting the sending terminal of the controller and the sending element of the upper-side communication driver, and the state of connecting the receiving element of the lower-side communication driver and the sending element of the upper-side communication driver. When sending a signal, the controller uses the communication switching switch to perform the processing of connecting the sending terminal of the controller and the sending element of the upper-side communication driver.

[0101] In the sixth aspect, in the lower device on the upper side, the controller can receive the signal transmitted from the lower side through the second receiving terminal and then transmit the signal from the transmitting terminal of the controller to the upper side.

[0102] [Seventh Method]

[0103] A seventh aspect is a robot characterized by including a communication system for performing communication between a plurality of devices daisy-chain-connected to each other via cables, wherein the communication system is the communication system of any one of the first to sixth aspects.

[0104] According to the seventh aspect, when there is no response from the lower device, communication can be performed using a communication system capable of collecting information useful for determining whether the cause is a cable failure or a failure of the lower device.

[0105] Description of labels

[0106] 50…main control unit (top-level device), 71…first lower-level control unit (lower-level device), 72…second lower-level control unit (lower-level device), 73…third lower-level control unit (lower-level device), 74…fourth lower-level control unit, 75…fifth lower-level control unit (lower-level device), C1 to C5…cables.

Claims

1. A communication system for performing communication between a plurality of devices connected to each other in a daisy chain via a cable, comprising: The highest-level device is a device that is at the highest level in the arrangement order among the multiple devices; and a plurality of lower-level devices, the plurality of lower-level devices being devices that are not located at the highest level in the arrangement order, wherein the communication system is characterized in that: It includes a power on / off unit, which switches on and off the power supply to each lower device individually. If communication fails between two devices that are arranged adjacent to each other, a confirmation process is performed to confirm whether there is any abnormality in the communication function of the upper-level device while power is cut off to the lower-level device of the two devices. Each lower device includes a controller, an upper-side communication driver, and a lower-side communication driver. The upper-side communication driver transmits a signal sent from the controller to the uppermost device or the lower-level device on the upper side, and transmits a signal sent from the uppermost device or the lower-level device on the upper side to the controller and the lower-side communication driver. The lower-side communication driver transmits a signal transmitted from the upper-side communication driver to the lower-level device on the lower-level side, and transmits a signal transmitted from the lower-level device on the lower-level side to the upper-side communication driver. The controller includes: a first receiving terminal connected to a receiving line, the receiving line connecting a receiving element of the upper-side communication driver and a transmitting element of the lower-side communication driver; and a second receiving terminal connected to a transmission line connecting the transmitting element of the upper-side communication driver and the receiving element of the lower-side communication driver.

2. The communication system according to claim 1, wherein The confirmation processing started based on the situation where communication between two lower devices adjacent to each other in the arrangement order is unsuccessful includes: a process of sending a test signal from the highest device; and a process of confirming in the lower device on the upper side of the two lower devices whether the controller receives the test signal received by the upper side communication driver via the lower side communication driver and the second receiving terminal.

3. The communication system according to claim 1, wherein The confirmation processing started based on the situation where communication between two lower devices adjacent to each other in the arrangement order is unsuccessful includes: a process of sending a test signal from the lower device adjacent to the upper side to the lower device on the upper side of the two lower devices; and a process of confirming in the lower device on the upper side of the two lower devices whether the controller receives the test signal received by the upper side communication driver via the lower side communication driver and the second receiving terminal.

4. The communication system according to claim 2 or 3, wherein: The power on / off unit is a switch configured on each lower device. The switch switches on and off the conduction of power sent from the upper side to the lower side.

5. The communication system according to claim 4, wherein: The controller of each lower device includes a communication switching switch, which switches the connection state between the state of connecting the sending terminal of the controller and the sending element of the upper-side communication driver, and the state of connecting the receiving element of the lower-side communication driver and the sending element of the upper-side communication driver. When transmitting a signal, the controller uses the communication switch to execute a process of connecting a transmission terminal of the controller and a transmission element of the upper-level communication driver.

6. A robot comprising a communication system for communicating between a plurality of devices daisy-chained to each other via cables, wherein: The communication system is the communication system according to any one of claims 1 to 5.

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