Composite fault-tolerant redundant position feedback and electronic control method for robot joint servo

Abstract

The present invention provides a robot joint servo composite fault-tolerant redundant position feedback and its electronic control method. Specifically, it includes a joint servo mechanical actuator unit and a joint servo position feedback electronic control unit, wherein the mechanical actuator is used to execute the command of the robot joint servo position feedback electronic control unit; the position feedback electronic control unit is mainly composed of redundant incremental position feedback, redundant absolute position feedback, etc., and the position feedback electronic control unit is used to detect and feedback the incremental and absolute position signals of the robot joint servo; for the position feedback electronic control unit management strategy, a gradient composite fault-tolerant strategy is adopted, which takes into account the full working condition service process of the robot joint servo. With the mutual cooperation between the mechanical actuator unit, the position feedback electronic control unit and the gradient composite fault-tolerant strategy, it is ensured that the robot joint always works in the position mode and can dynamically follow the position and speed instructions issued by the main controller in real time.

Description

Technical Field

[0001] The present invention belongs to the field of artificial intelligence special equipment robots, and in particular relates to a robot joint servo composite fault-tolerant position redundant feedback and an electric control method thereof. Technical Background

[0002] The harmonic reducer, servo, and main controller are the three core components of a robot system. The harmonic reducer is a crucial component of the robot joint's mechanical structure. Installed in the robot joint, the harmonic reducer can boost the output torque of the large hollow servo joint motor, achieving a deceleration-torque-increasing effect. It can also improve the control resolution and closed-loop accuracy of the robot joint servo, thereby matching the power output parameters. The harmonic reducer consists of an elliptical wave generator, a flexible wheel, and a rigid wheel. During operation, the elliptical wave generator compresses the flexible wheel, causing it to elastically deform. The meshing of the flexible wheel's external teeth with the rigid wheel's internal teeth achieves a deceleration effect. The harmonic reducer's internal mechanical structure is complex and sophisticated, with numerous sources of internal friction. It also exhibits a certain degree of compliance. When assembled with the robot joint, the harmonic reducer also imparts a certain degree of compliance, resulting in significant nonlinearity in power input and output. These characteristics result in high precision for the harmonic reducer, but due to nonlinearity, the specific location of each robot joint's power output is random and uncertain. In theory, it is not a precise position, but rather a fluctuation around a specific location. In addition, the harmonic reducer has a large reduction ratio. The above characteristics make it impossible to directly determine the output of the robot joint based on the relationship between the input and the reduction ratio, especially the absolute position of the robot joint output. Its absolute position also involves the absolute calibration problem at the end position of the joint.

[0003] To address this issue, current engineering practices typically install an absolute position encoder directly at the output of the harmonic reducer, enabling direct physical detection through sensors and hardware circuits, such as a resolver or absolute position sensor for position feedback. A resolver is typically a miniature signal motor that measures angle or speed signals. As a signal motor, the resolver itself is constructed of silicon steel sheets and enameled wire, without any internal electronic components. This construction offers numerous advantages, including high radiation resistance, strong vibration and temperature resistance, and robustness in harsh environments. Furthermore, resolver accuracy generally reaches below 5 arc minutes. For applications with demanding precision, high-end multi-pole logarithmic resolvers are often used to significantly improve accuracy. The electrical error of such high-end multi-pole resolvers can be controlled to within a few arc seconds (0.1-0.01°). While high-end multi-pole resolvers offer a certain degree of accuracy, this still falls short of the high-precision (<0.01°) required for robot servo applications, such as positioning, gripping, welding, and polishing. These resolvers are only suitable for non-high-precision entry / exit and initialization tasks. Furthermore, because resolvers output analog signals, specialized signal conditioning circuits and decoding chips are required, leading to a complex decoding process. Furthermore, in radiation-prone environments, the decoding circuitry is also susceptible to radiation-induced failures.

[0004] However, in response to various problems with resolvers, robot servo joint servo systems usually use absolute position sensors such as photoelectric encoders or magnetic encoders. The advantage of this is that the accuracy can meet the high-precision operation requirements of the robot joint servo, and the volume can be very small. However, since the above-mentioned photoelectric or magnetic position sensors are made of special materials, they are very sensitive to radiation and vibration. They are one of the weak links in the entire robot joint servo system, which limits the radiation resistance of the position sensor and also limits the working performance of the robot joint servo in a radiation environment.

[0005] Typically, the encoder disk of a photoelectric or magnetic position encoder undergoes special absolute position calibration. Through a conditioning circuit, the photoelectric or magnetic position encoder can directly read the position signal at the end of the reducer and feed this position signal back to the MCU controller. This absolute position signal directly participates in the closed-loop position calculation of the robot joint servo system. Therefore, the robot joint servo system must implement a closed-loop position to follow the position commands issued by the master controller and maintain the expected accuracy. Therefore, the accuracy and reliability of the photoelectric or magnetic position encoder in the physical circuit hardware directly determine the dynamic tracking performance, accuracy, interference immunity, and reliability of the robot joint servo. Similarly, the incremental position signal at the output of the robot joint servo motor is currently typically installed directly on the joint motor end of the engineering practice. The incremental position signal is detected through physical hardware and fed directly back to the MCU controller. This incremental position signal directly participates in the speed and current loop calculations of the servo driver, particularly the speed loop of the intermediate loop. Because the position angle signal of the joint motor must be included in the voltage inversion process of the robot joint servo driver, the accuracy and reliability of the incremental position encoder in the physical hardware directly determine whether the servo joint motor can operate properly. However, in the harsh environments of aerospace and the nuclear industry, which have a certain dose of radiation, photoelectric or magnetic absolute position encoders and incremental position encoders are prone to failure due to radiation effects. This can easily cause the robot joint servo system, which must rely on sensors to collect position signals to operate normally, to be unable to obtain position signals and shut down due to sensor failure. Therefore, it is very important to prevent the robot joint servo system from shutting down due to position feedback sensor failure, and how to automatically select the corresponding fault tolerance strategy according to the type and severity of the sensor fault when a sensor fails, so as to compound the fault tolerance and ensure that the robot joint servo driver always operates in position mode and can dynamically follow the position and speed instructions issued by the main controller in real time.

[0006] Furthermore, fault tolerance is essentially a strategy for managing software and hardware circuits. Its implementation must rely on corresponding redundant hardware circuits. Therefore, the implementation of a composite fault-tolerance strategy for robot joint servos requires corresponding redundant hardware. Furthermore, when designing specialized equipment for the nuclear industry and aerospace, both software and hardware must adhere to the principle that similar redundancy cannot suppress common-mode failures and the principles of independence, diversity, and redundancy based on radiation-tolerant design. Summary of the Invention

[0007] In view of the problems described in the technical background of the present invention, the purpose of the present invention is to solve the problem of radiation failure effects in the position feedback of robot joint servo systems in nuclear radiation environments, which in turn causes the robot joint servo to stop and cannot function normally. To this end, the present invention provides a robot joint servo composite fault-tolerant redundant position feedback and its electronic control method;

[0008] In the present invention, for the incremental position feedback signal required for the speed closed loop and current closed loop in the robot joint servo system, the present invention designs a dual-redundant incremental position feedback of a resolver and an incremental encoder at the output end of the robot joint servo torque motor from the perspective of redundant hardware. In terms of the composite fault-tolerant strategy, the dual-redundant incremental position feedback adopts a gradient composite fault-tolerant strategy. The fault-tolerant strategy is based on the gradient working conditions of the robot's high-precision operation and non-high-precision operation, and can automatically start and switch different feedback modules in the dual-redundant incremental position feedback. In addition, in terms of the composite fault-tolerant strategy, a virtual incremental position sensor constructed by introducing a high-frequency injection start-up algorithm and a sensorless state observer algorithm can ensure that even if the hardware circuit detection of the dual-redundant incremental position feedback sensor fails completely, relying solely on the above-mentioned composite fault-tolerant strategy can still ensure that the robot joint servo torque motor moves normally without being stuck. This is also one of the problems to be solved and one of the purposes of the invention.

[0009] In addition, in the present invention, for the absolute position feedback signal required for the position closed loop in the robot joint servo system, the present invention designs a triple redundant absolute position feedback system at the output end of the robot harmonic reducer, including a flange force sensor, a resolver, and an absolute position encoder, from the perspective of redundant hardware. In terms of the composite fault-tolerant strategy, the triple redundant absolute position feedback adopts a gradient composite fault-tolerant strategy. This fault-tolerant strategy is based on the gradient operating conditions of the robot's high-precision operation and non-high-precision operation. It can automatically start and switch different feedback modules in the triple redundant absolute position feedback, and provide the robot joint servo system with real-time feedback of the absolute position signal of the joint, ensuring that the robot joint servo driver always operates in position mode and can dynamically follow the position and speed instructions issued by the main controller in real time.

[0010] The technical solution of the present invention provides a robot joint servo composite fault-tolerant redundant position feedback and an electronic control method thereof, comprising a robot joint servo mechanical execution unit and a robot joint servo redundant position feedback electronic control unit, characterized in that:

[0011] The robot joint servo mechanical execution unit includes a servo torque motor, a harmonic reducer, a reduction shaft, a joint transition elbow, an output flange force sensor, and a robot joint housing;

[0012] The servo torque motor, the harmonic reducer, the servo torque motor output disc sleeve, the reduction shaft, the joint brake, the brake disc and the brake fixing member all have a central hole and are coaxial with the central axis of the robot joint housing;

[0013] The deceleration shaft is located inside the robot joint housing, and the deceleration shaft has a two-step shaft, wherein the diameter of the first step shaft is larger than the diameter of the second step shaft; the shaft end of the first step shaft has the output flange force sensor, and the output flange force sensor is connected to the joint transition elbow through a mounting hole and a connecting piece;

[0014] The harmonic reducer, the servo torque motor, the servo torque motor output disc sleeve, the joint brake, the brake disc and the brake fixing member are sequentially installed from the output flange force sensor of the first step shaft of the reduction shaft toward the second step shaft;

[0015] The servo torque motor output disc sleeve is connected to the servo torque motor through a mounting hole and a connector. The second stepped shaft on the reduction shaft passes through the servo torque motor output disc sleeve, ensuring that there is a gap between the servo torque motor output disc sleeve and the reduction shaft, so that the power transmission between the reduction shaft and the servo torque motor output disc sleeve is independent of each other and does not interfere with each other.

[0016] The joint brake, the brake disc and the brake fixing member are fitted onto the servo torque motor output disc sleeve by interference fit, ensuring that the speed torque and incremental position signal of the servo torque motor are directly transmitted to the servo torque motor output disc sleeve and the joint brake;

[0017] The robot joint servo redundant position feedback electronic control unit includes redundant incremental position feedback, redundant absolute position feedback, a low-voltage power supply board, a servo drive board, an MCU control board and a sensor perception board;

[0018] The redundant incremental position feedback in the robot joint servo redundant position feedback electronic control unit includes a first resolver and an incremental position encoder;

[0019] In order to feed back the incremental position of the robot joint servo to the MCU control board, the first resolver and the incremental position encoder must be installed on the second stepped shaft of the reduction shaft, and the first resolver and the incremental position encoder must be interference fitted with the servo torque motor output disc sleeve to ensure that the torque output of the servo torque motor rotor is transmitted to the first resolver and the incremental position encoder through the servo torque motor output disc sleeve, ensuring that the first resolver and the incremental position encoder jointly detect the incremental position signal at the output end of the servo torque motor rotor and feed back the incremental position signal to the MCU control board. The incremental position signal participates in the closed-loop operation of the speed loop and current loop followed by the robot joint servo.

[0020] Furthermore, when the robot servo joint loses power and stops, the joint brake will receive a command from the MCU control board and automatically power on and start. The joint brake tightly attracts the brake disc through electromagnetic force, thereby achieving emergency braking of the servo torque motor. At this time, the first resolver and the incremental position encoder in the redundant incremental position feedback stop feeding back incremental position signals to the MCU control board.

[0021] Furthermore, the low-voltage power supply board provides normal operating voltage for the first resolver and the incremental position encoder of the redundant incremental position feedback in the redundant position feedback electronic control unit of the robot joint servo. The servo drive board provides drive for the entire robot joint servo, thereby driving the first resolver and the incremental position encoder to rotate. The MCU control board is used to receive the robot incremental position signal fed back by the first resolver and the incremental position encoder. The sensor perception board integrates the signal conditioning circuit of the first resolver and the incremental position encoder to ensure that the signals of the first resolver and the incremental position encoder are not distorted when they are working.

[0022] Furthermore, the redundant absolute position feedback in the robot joint servo redundant position feedback electronic control unit includes the output flange force sensor, the second resolver and the absolute position encoder;

[0023] In order to feed back the absolute position of the robot joint servo to the MCU control board, the second resolver and the absolute position encoder must be interference-fitted on the second stepped shaft of the reduction shaft, and the output flange force sensor must be interference-fitted on the first stepped shaft of the reduction shaft. The output flange force sensor is connected to the joint elbow through a mounting hole and a connector, and the joint elbow is connected to the robot connecting rod, ensuring that the output flange force sensor detects the absolute positions of the joint elbow and the robot connecting rod. The absolute positions of the joint elbow and the robot connecting rod are also the absolute positions of the robot joint servo output;

[0024] The harmonic reducer input disk is connected to the servo torque motor rotor through a mounting hole and a connector, and receives the torque of the servo torque motor rotor. The harmonic reducer is connected to the harmonic reducer input disk through a mounting hole and a connector. The first stepped shaft of the reduction shaft is connected to the harmonic reducer through interference fitting. The above assembly relationship ensures that the torque of the servo torque motor rotor is transmitted to the reduction shaft after being decelerated and torque-increased by the harmonic reducer.

[0025] The second step shaft of the reduction shaft is interference-fitted with the second resolver and the absolute position encoder. The torque output of the harmonic reducer drives the second resolver and the absolute position encoder to rotate together, and the two together detect the absolute position of the robot joint servo output.

[0026] The interference fit positions of the second resolver, the absolute position encoder, and the output flange force sensor on the first stepped shaft and the second stepped shaft of the reduction shaft cannot be replaced;

[0027] The electromechanical assembly relationship of the redundant absolute position feedback ensures that the second resolver, the absolute position encoder and the output flange force sensor all detect the absolute position of the robot joint servo and feed back the absolute position of the robot joint servo to the MCU control board.

[0028] Furthermore, the low-voltage power supply board provides normal operating voltage for the second resolver, the absolute position encoder and the output flange force sensor of the redundant absolute position feedback in the redundant position feedback electronic control unit of the robot joint servo. The servo drive board provides drive for the entire robot joint servo, thereby driving the second resolver, the absolute position encoder and the output flange force sensor to rotate. The MCU control board is used to receive the robot absolute position signal fed back by the second resolver, the absolute position encoder and the output flange force sensor. The sensor perception board integrates the signal conditioning circuit of the second resolver, the absolute position encoder and the output flange force sensor to ensure that the signals of the second resolver, the absolute position encoder and the output flange force sensor are not distorted when they are working.

[0029] Furthermore, the output flange force sensor in the redundant absolute position feedback includes the output flange force sensor body, the output flange force sensor transmitter and the output flange force sensor rear end;

[0030] The output flange force sensor body includes the spokes, the elastic body, and the strain gauges. The strain gauges are bonded and mounted in multiple groups on the inner wall of the spokes of the elastic body. The multiple groups of strain gauges form a strain matrix bridge. The strain matrix bridge can sense the force / torque applied to the robot joint servo during rotation in real time.

[0031] The output flange force sensor transmitter includes the signal conditioning circuit and the AD converter, which is used to amplify and condition the strain matrix bridge output signal of the output flange force sensor body and perform active filtering, and convert the signal into a digital signal for transmission to the MCU control board;

[0032] The rear end of the output flange force sensor includes the MCU control board, and the MCU lower layer controller and the MCU upper layer controller are respectively integrated into the MCU control board through integrated circuit technology;

[0033] The MCU lower-layer controller further digitally filters and performs state evaluation on the absolute position signal conditioned and transmitted by the output flange force sensor transmitter, and the MCU upper-layer controller participates in the position closed-loop calculation process of the robot joint servo based on the absolute position signal, all of which are completed inside the MCU control board 13;

[0034] The output flange force sensor is controlled by a separate power supply circuit and is in a cold standby state for a long time, without performing absolute position feedback output;

[0035] After the hard decoding circuit and soft decoding circuit of the second resolver in the redundant absolute position feedback, and the absolute position encoder all fail, the output flange force sensor starts working from the cold backup state and feeds back the absolute position of the robot servo joint to the MCU control board.

[0036] Furthermore, the output flange force sensor independent power supply circuit includes a first N-type MOS transistor N1, a first P-type MOS transistor P1 and an operational amplifier follower circuit OP1;

[0037] In terms of the connection mode of the separate power supply circuit of the output flange force sensor, the gate of the first N-type MOS transistor N1 is connected to the MCU lower-layer controller on the MCU control board, the drain of the first N-type MOS transistor N1 is connected to the gate of the first P-type MOS transistor P1, the source of the first P-type MOS transistor P1 is connected to the low-voltage power supply board, and the drain output of the first P-type MOS transistor P1 is connected to the positive input terminal of the operational amplifier follower circuit OP1 through a voltage divider resistor, and the output terminal of the operational amplifier follower circuit OP1 is directly connected to the output flange force sensor transmitter;

[0038] The gate of the first N-type MOS transistor N1 receives the arbitration signal sent by the MCU lower-layer controller, indicating that the hard decoding circuit and the soft decoding circuit of the second resolver, as well as the absolute position encoder, have all failed and are in an abnormal working state. The first N-type MOS transistor N1 is turned on, the first P-type MOS transistor P1 is turned on, the output end of the operational amplifier follower circuit OP1 directly follows the input end, and the output end of the operational amplifier follower circuit OP1 directly supplies power to the output flange force sensor transmitter. The output flange force sensor transmitter starts to work;

[0039] The MCU lower-layer controller does not send an arbitration signal, indicating that the hard decoding circuit and the soft decoding circuit of the second resolver, as well as the absolute position encoder, are operating normally, the first N-type MOS transistor N1 is turned off, the first P-type MOS transistor P1 is turned off, and the output flange force sensor is in an unpowered backup redundant cold standby state.

[0040] Furthermore, the second resolver in the redundant absolute position feedback includes the second resolver hard decoding circuit and the second resolver soft decoding circuit, wherein the second resolver hard decoding circuit includes the hard decoding chip circuit, the current buffer and the MCU control board, and the second resolver soft decoding circuit includes the signal conditioning circuit and the second resolver cold redundant power supply circuit;

[0041] The fault tolerance process of the second resolver in the redundant absolute position feedback can be described as follows:

[0042] Step 1: When the second resolver and the absolute position encoder are working normally, they are used to detect and feed back the absolute position signal of the robot joint servo to the MCU control board. The second resolver hard decoding circuit and the absolute position encoder are directly powered by the low-voltage power supply board 11.

[0043] Step 2: The MCU lower-layer controller on the MCU control board does not send an arbitration signal to the second resolver cold redundant power supply circuit, and the soft decoding circuit of the second resolver is not started. At this time, the first N-type MOS transistor N1 is turned off, the first P-type MOS transistor P1 is turned off, and the drain output end of the first P-type MOS transistor P1 does not supply power to the outside. The soft decoding circuit of the second resolver is always in a no-power cold standby state;

[0044] Step 3: When a fault occurs in the second resolver hard decoding chip circuit in the redundant absolute position feedback, the MCU lower layer controller on the MCU control board sends an arbitration signal to the second resolver cold redundant power supply circuit, and the second resolver soft decoding circuit starts to start;

[0045] Step 4: After the second rotary variable cold redundant power supply circuit receives the arbitration signal from the MCU control board, the first N-type MOS transistor N1 in the second rotary variable cold redundant power supply circuit is turned on, the first P-type MOS transistor P1 is turned on, and the drain output end of the first P-type MOS transistor P1 directly supplies independent power to the signal conditioning circuit in the second rotary variable soft decoding circuit;

[0046] Step 5: The startup and independent power supply of the second resolver soft decoding circuit are completed, the switching of the backup cold redundancy work is completed, the absolute position of the robot joint servo is detected, and the absolute position of the robot joint servo is fed back to the MCU control board, thereby realizing the fault tolerance of the second resolver.

[0047] Furthermore, the output flange force sensor, the second resolver and the absolute position encoder in the redundant absolute position feedback adopt a gradient composite fault-tolerant strategy, which can effectively manage the output flange force sensor, the second resolver and the absolute position encoder in the redundant absolute position feedback;

[0048] The gradient composite fault-tolerance strategy takes into account the robot joint servo's service process under all working conditions, including high-precision operation, non-high-precision operation, and emergency return. When any one or more absolute position feedbacks fail simultaneously under all working conditions, the mutual fault-tolerance strategy between the output flange force sensor, the second resolver, and the absolute position encoder is adopted. The fault-tolerance process can be described as follows:

[0049] Step 1: When the robot joint servo is not operating in high-precision mode, the MCU control board automatically switches to the hard decoding of the second resolver, relying on the hard decoding of the second resolver to meet the non-precision operation. During this process, the soft decoding circuit of the second resolver is not started, and the soft decoding of the second resolver is always in a cold backup redundant state.

[0050] Step 2: When the robot joint servo is operating with high precision, the MCU control board will automatically start the absolute position encoder, the second resolver, and the second resolver hard decoding circuit. The lower-level controller of the MCU control board simultaneously reads the absolute position data of the absolute position encoder and the absolute position data of the second resolver hard decoding. The lower-level controller of the MCU control board fuses the absolute position data of the absolute position encoder and the absolute position data of the second resolver hard decoding circuit through a data fusion algorithm to obtain a robot joint servo absolute position signal with higher precision. The upper-level controller of the MCU control board uses the fused absolute position data signal as the final position closed-loop signal of the robot joint servo to participate in the closed-loop operation of the robot joint servo position loop. During this process, the soft decoding circuit of the second resolver is not started, and the soft decoding of the second resolver is always in a backup cold redundant state.

[0051] Step 3: When the robot joint servo operates normally with high precision, the hard decoding chip circuit of the second resolver and the absolute position encoder work simultaneously and serve as the main decoding circuit. When the absolute position encoder fails, the soft decoding circuit of the second resolver starts to start. At this time, the second resolver's soft decoding and hard decoding circuits continue to provide absolute position feedback for the robot joint servo.

[0052] Step 4: As the working time increases, when the second rotary hard decoding chip circuit fails, the MCU control board starts the output flange force sensor, and the output flange force sensor continues to provide absolute position feedback for the robot joint servo. At this time, the robot is passively in an emergency return to a non-high-precision working state;

[0053] Step 5: All redundant absolute position feedback hardware circuits of the robot joint servo fail simultaneously. The MCU control board adopts variable frequency speed regulation and absolute position open loop. At this time, the robot is passively in an emergency return non-high-precision operation state.

[0054] Furthermore, the redundant incremental position feedback in the robot joint servo redundant position feedback electronic control unit is composed of the first resolver and the incremental position encoder;

[0055] When the redundant incremental position feedback first resolver and the incremental position encoder all fail, the MCU control board will automatically switch to the sensorless high-frequency injection startup algorithm. The MCU control board constructs a state observer virtual sensor for state output, and the state estimates the incremental position signal of the servo torque motor. At the same time, the incremental position signal is fed back to the MCU control board, and the incremental position signal participates in the speed closed-loop control of the MCU control board.

[0056] Beneficial effects of the present invention:

[0057] First, in the present invention, the output flange force sensor used in redundant incremental position feedback does not contain microelectronic circuitry, exhibits strong resistance to harsh environments, possesses high radiation resistance, and, after rigorous physical parameter calibration, achieves high absolute position accuracy. Therefore, it serves as a backup for absolute position feedback in robot joint servos. Furthermore, to ensure the compactness and lightweight nature of the robot joints, the output flange force sensor is designed in the form of an output flange. This not only outputs joint torque but also identifies the absolute position of the robot joint output, thus balancing the dual functions of joint torque output and joint servo absolute position identification.

[0058] Second, in the present invention, based on the principle that similar redundancy cannot suppress common mode failure and the principles of independence, diversity and redundancy based on radiation-resistant design, in the present invention, the accuracy of the four types of absolute position encoders, second rotary hard decoding, second rotary soft decoding and output flange force sensors for obtaining the absolute position of the robot joint servo is successively reduced. When the gradient composite fault-tolerant strategy manages the above-mentioned hardware circuits, combined with the robot joint servo operating conditions, the priority is always given to hardware precision absolute position feedback. The implementation and development of the above-mentioned gradient composite fault-tolerant management strategy can at least ensure that the joint movement will not be stuck, no matter what working state the robot joint servo absolute position feedback circuit is in, and can significantly improve the service time of the robot joint servo in extreme environments such as radiation.

[0059] Third, the gradient composite fault-tolerant strategy of the present invention takes into account the full working condition service process of the robot joint servo in a radiation environment, including high-precision operation, non-high-precision operation, and emergency return. When any one or more absolute position feedback circuits simultaneously experience radiation failure effects under all working conditions, the mutual fault-tolerant strategy between the output flange force sensor, the second resolver and the absolute position encoder in the redundant absolute position feedback is used to ensure as much as possible the absolute position signal required for the robot joint servo position closed loop. The absolute position signal directly determines the positioning accuracy, follow-up response speed and anti-disturbance performance of the robot joint servo.

[0060] Fourth, the gradient composite fault-tolerant strategy of the present invention takes into account the full working condition service process of the robot joint servo in a radiation environment, including high-precision operation, non-high-precision operation, and emergency return. When any one or more incremental position feedback circuits have radiation failure effects at the same time under all working conditions, the mutual fault-tolerant strategy between the first resolver and the incremental position encoder in the redundant incremental position feedback ensures and improves the incremental position signal to the current closed loop and speed closed loop of the robot joint servo motor as much as possible. The incremental position signal directly participates in the inversion operation of the three-phase AC power of the servo drive, which directly determines whether the servo motor can operate normally.

[0061] Fifth, in the present invention, the mechanical structure and assembly corresponding to the redundant incremental position feedback and redundant absolute position feedback in the robot joint servo position feedback, the circuit system architecture, the power supply method, the cold redundant power supply circuit, and the gradient composite fault-tolerant strategy for managing redundant position feedback are not only applicable to robot joint servos, but also to intelligent tracked chassis with position feedback, CNC machine tools, radars and other equipment with high-precision position feedback, and have certain scalability. BRIEF DESCRIPTION OF THE DRAWINGS

[0062] Figure 1 It is a diagram of the composition of the robot joint servo composite fault-tolerant redundant position feedback;

[0063] Figure 2 This is a schematic diagram of the robot joint servo composite fault-tolerant redundant position feedback architecture;

[0064] Figure 3 This is the assembly diagram of the robot joint redundant servo position feedback hardware circuit;

[0065] Figure 4 This is the overall assembly diagram of the mechanical and electrical structure of the robot joint redundant servo position feedback hardware;

[0066] Figure 5 This is a schematic diagram of the mechanical structure of the output flange force sensor in absolute position feedback;

[0067] Figure 6 It is a schematic diagram of the transmission process between force and absolute position signal of robot joint;

[0068] Figure 7 This is a schematic diagram of the separate power supply circuit for the output flange force sensor transmitter;

[0069] Figure 8 This is a diagram of the redundant absolute position feedback circuit;

[0070] Figure 9 This is a schematic diagram of the entire process of rotational hard decoding and backup cold redundancy soft decoding;

[0071] Figure 10 This is a schematic diagram of the resolver soft decoding backup cold redundant independent power supply circuit;

[0072] Figure 11 This is a schematic diagram of a redundant absolute position feedback gradient composite fault-tolerant management strategy;

[0073] Figure 12 This is a working diagram of the redundant incremental position state observer virtual sensor;

[0074] Figure 13This is a schematic diagram of the relationship between the robot joint servo position feedback and three-loop control.

[0075] Among them: 1-output flange force sensor, 2-harmonic reducer, 3-harmonic reducer input disk, 4-servo torque motor, 5-servo torque motor rotor, 6-servo torque motor output disk sleeve, 7-first resolver, 8-joint brake, 9-second resolver, 10-absolute position encoder, 11-low-voltage power supply board, 12-servo drive board, 13-MCU control board, 14-sensor sensing board, 15-brake disc, 16-brake fixing part, 17-incremental position encoder, 18-reduction shaft, 19-joint transition elbow, 20-spoke, 21-elastic body, 22-strain gauge, 23-robot joint housing, 24-robot connecting rod. DETAILED DESCRIPTION

[0076] In order to more clearly understand the above-mentioned objectives, features and advantages of the present application, the present application is further described in detail below in conjunction with the accompanying drawings and specific embodiments. It should be noted that the embodiments of the present application and the features therein can be combined with each other in the absence of conflict.

[0077] like Figure 1 、 Figure 2 、 Figure 3 and Figure 4 As shown, this embodiment provides a robot joint servo composite fault-tolerant redundant position feedback and an electronic control method thereof, specifically including a robot joint servo mechanical execution unit and a robot joint servo redundant position feedback electronic control unit.

[0078] like Figure 4 As shown, the robot joint servo mechanical execution unit consists of a servo torque motor 4, a harmonic reducer 2, a reduction shaft 18, a joint transition elbow 19, an output flange force sensor 1, a robot joint housing 23 and necessary connectors. The robot joint servo mechanical execution unit is used to execute the commands of the robot joint servo redundant position feedback electronic control unit and plays an indispensable hardware support role in the execution of the robot joint servo composite fault-tolerant redundant position feedback and its electronic control method.

[0079] like Figure 4 As shown, the assembly relationship of the robot joint servo mechanical actuator can be described as follows: the servo torque motor 4, the harmonic reducer 2, the servo torque motor output disc sleeve 6, the reduction shaft 18, the joint brake 8, the brake disc 15 and the brake fixing member 16 all have a center hole and are coaxial with the center axis of the robot joint housing 23;

[0080] The reduction shaft 18 is located inside the robot joint housing 23. The reduction shaft 18 has a two-step shaft, and the diameter of the first step shaft is larger than the diameter of the second step shaft. The shaft end of the first step shaft has an output flange force sensor 1, and the output flange force sensor 1 is connected to the joint transition elbow 19 through a mounting hole and a connector. The harmonic reducer 2, servo torque motor 4, servo torque motor output disc sleeve 6, joint brake 8, brake disc 15, and brake fixing part 16 are sequentially installed from the output flange force sensor 1 of the first step shaft of the reduction shaft 18 toward the second step shaft.

[0081] The servo torque motor output disc sleeve 6 is connected to the servo torque motor 4 through the mounting holes and the connector. The second stepped shaft on the reduction shaft 18 passes through the servo torque motor output disc sleeve 6. This ensures that there is a gap between the servo torque motor output disc sleeve 6 and the reduction shaft 18, so that the power transmission between the reduction shaft 18 and the servo torque motor output disc sleeve 6 is independent of each other and will not interfere with each other.

[0082] In the present invention, the joint brake 8, the brake disc 15 and the brake fixing part 16 are assembled onto the servo torque motor output disc sleeve 6 by interference fit. The above assembly relationship ensures that the speed torque and incremental position signal of the servo torque motor 4 are directly transmitted to the servo torque motor output disc sleeve 6 and the joint brake 8.

[0083] like Figure 1 、 Figure 2 、 Figure 3 and Figure 4 As shown, the robot joint servo redundant position feedback electronic control unit consists of redundant incremental position feedback, redundant absolute position feedback, a low-voltage power supply board 11, a servo drive board 12, an MCU control board 13, and a sensor sensing board 14. The robot joint servo redundant position feedback electronic control unit is used to detect and feedback the incremental position and absolute position signals of the robot joint servo to the MCU control board 13. It is the core link in the execution process of the robot joint servo composite fault-tolerant redundant position feedback and its electronic control method. It ensures that the robot joint servo always works in the position mode and can dynamically follow the position and speed instructions issued by the main controller in real time.

[0084] like Figure 4 As shown, the redundant incremental position feedback in the robot joint servo redundant position feedback electronic control unit is composed of a first resolver 7 and an incremental position encoder 17;

[0085] The incremental position feedback in the robot joint servo position feedback is to feed back the incremental position signal of the robot joint servo motor to the MCU control board 13. This signal directly participates in the inversion operation of the three-phase AC power of the servo drive and directly determines whether the servo motor can operate normally.

[0086] The redundant incremental position feedback of the robot servo joint is closely related to its electromechanical assembly position. Therefore, in order to detect and feedback the incremental position of the robot joint servo to the MCU control board 13, the first resolver 7 and the incremental position encoder 17 must be installed at the second stepped shaft of the reduction shaft 18, and the first resolver 7 and the incremental position encoder 17 must be interference fitted with the servo torque motor output disc sleeve 6. This electromechanical assembly relationship ensures that the torque output of the servo torque motor rotor 5 is transmitted to the first resolver 7 and the incremental position encoder 17 through the servo torque motor output disc sleeve 6, thereby ensuring that the first resolver 7 and the incremental position encoder 17 jointly detect the incremental position signal of the output end of the servo torque motor rotor 5, and feed the incremental position signal back to the MCU control board 13. The incremental position signal participates in the closed-loop operation of the speed loop and current loop followed by the robot joint servo.

[0087] In the present invention, when the robot servo joint loses power and stops, the joint brake 8 receives a command from the MCU control board 13 and automatically powers on and starts. The joint brake 8 tightly attracts the brake disc 15 through electromagnetic force, thereby achieving emergency braking of the servo torque motor 4. At this time, the first resolver 7 and the incremental position encoder 17 in the redundant incremental position feedback stop feeding back incremental position signals to the MCU control board 13.

[0088] like Figure 2 and Figure 3 As shown, in the present invention, the low-voltage power supply board 11 provides normal operating voltage for the first resolver 7 and the incremental position encoder 17 of the redundant incremental position feedback in the redundant position feedback electronic control unit of the robot joint servo, the servo drive board 12 provides drive for the entire robot joint servo, thereby driving the first resolver 7 and the incremental position encoder 17 to rotate, the MCU control board 13 is used to receive the robot incremental position signal fed back by the first resolver 7 and the incremental position encoder 17, and the sensor perception board 14 integrates the signal conditioning circuit of the first resolver 7 and the incremental position encoder 17 to ensure that the signals of the first resolver 7 and the incremental position encoder 17 are not distorted when they are working.

[0089] like Figure 1 、 Figure 2 、 Figure 3 and Figure 4 As shown, the redundant absolute position feedback in the robot joint servo redundant position feedback electronic control unit is composed of an output flange force sensor 1, a second resolver 9 and an absolute position encoder 10;

[0090] The absolute position feedback in the robot joint servo position feedback is the absolute position signal of the robot joint servo output end fed back to the MCU control board. This signal directly participates in the position loop of the servo drive three-loop control and is the true value of the position closed-loop control. This position signal directly determines the positioning accuracy, following response speed and anti-disturbance performance of the robot joint servo.

[0091] The redundant absolute position feedback of the robot servo joint is closely related to its electromechanical assembly position. Therefore, in order to detect and feedback the absolute position of the robot joint servo to the MCU control board 13, the second resolver 9 and the absolute position encoder 10 must be interference fitted at the second stepped shaft of the reduction shaft 18, and the output flange force sensor 1 is interference fitted at the first stepped shaft of the reduction shaft 18. The output flange force sensor 1 is connected to the joint elbow 19 through the mounting hole and the connector, and the joint elbow 19 is connected to the robot connecting rod 24. Therefore, this electromechanical assembly relationship ensures that the output flange force sensor 1 detects the absolute position of the joint elbow 19 and the robot connecting rod 24. The absolute position of the joint elbow 19 and the robot connecting rod 24 is also the absolute position of the robot joint servo output.

[0092] The harmonic reducer input disc 3 is connected to the servo torque motor rotor 5 through the mounting holes and connectors, and receives the torque of the servo torque motor rotor 5. The harmonic reducer 2 is connected to the harmonic reducer input disc 3 through the mounting holes and connectors. The first step shaft of the reduction shaft 18 is connected to the harmonic reducer 2 by interference fit, which ensures that the torque of the servo torque motor rotor 5 is transmitted to the reduction shaft 18 after being decelerated and torque-increased by the harmonic reducer 2.

[0093] The second step shaft of the reduction shaft 18 is interference-fitted with the second resolver 9 and the absolute position encoder 10. The torque output of the harmonic reducer 2 drives the second resolver 9 and the absolute position encoder 10 to rotate together. The two together detect the absolute position of the robot joint servo output.

[0094] The interference fit positions of the second resolver 9, the absolute position encoder 10 and the output flange force sensor 1 on the first and second step shafts of the reduction shaft 18 cannot be replaced;

[0095] In the present invention, the electromechanical assembly relationship of the redundant absolute position feedback ensures that the second resolver 9, the absolute position encoder 10 and the output flange force sensor 1 all detect the absolute position of the robot joint servo and feed back the absolute position of the robot joint servo to the MCU control board 13.

[0096] like Figure 2 and Figure 3As shown, in the present invention, the low-voltage power supply board 11 provides normal operating voltage for the second resolver 9, absolute position encoder 10 and output flange force sensor 1 of redundant absolute position feedback in the robot joint servo redundant position feedback electronic control unit, and the servo drive board 12 provides drive for the entire robot joint servo, thereby driving the second resolver 9, absolute position encoder 10 and output flange force sensor 1 to rotate, and the MCU control board 13 is used to receive the robot absolute position signal fed back by the second resolver 9, absolute position encoder 10 and output flange force sensor 1, and the sensor sensing board 14 integrates the signal conditioning circuit of the second resolver 9, absolute position encoder 10 and output flange force sensor 1 to ensure that the signals of the second resolver 9, absolute position encoder 10 and output flange force sensor 1 are not distorted when working.

[0097] like Figure 5 and Figure 6 As shown, the output flange force sensor 1 in the redundant absolute position feedback is composed of the output flange force sensor 1 body, the output flange force sensor 1 transmitter and the output flange force sensor 1 rear end;

[0098] The output flange force sensor 1 consists of spokes 20, an elastomer 21, and strain gauges 22. Multiple groups of strain gauges 22 are adhesively mounted on the inner wall of the spokes 20 of the elastomer 21. These multiple groups of strain gauges form a strain matrix bridge, which can sense the forces / torques acting on the robot joint servo in real time. Based on the principle of vectorial force, different angles of robot joint rotation produce forces of varying magnitude and direction, corresponding to different output values ​​from the strain matrix bridge. The bridge output value has a one-to-one correspondence with the robot joint servo rotation angle, allowing parameter calibration to determine the absolute position signal of the robot joint servo rotation angle.

[0099] Among them, the transmitter of the output flange force sensor 1 is composed of a signal conditioning circuit and an AD converter, which is used to amplify and condition the output signal of the strain matrix bridge of the output flange force sensor 1 body, actively filter and condition it, and convert it into a digital signal and transmit it to the MCU control board 13;

[0100] The back end of the output flange force sensor 1 is composed of an MCU control board 13. The MCU lower-layer controller and the MCU upper-layer controller are integrated into the MCU control board 13 through integrated circuit technology. The MCU lower-layer controller further digitally filters and evaluates the robot joint servo absolute position signal conditioned and transmitted by the output flange force sensor 1 through the transmitter, and transmits the absolute position signal to the MCU upper-layer controller. The MCU upper-layer controller participates in the position closed-loop calculation of the robot joint servo based on this absolute position signal.

[0101] The above-mentioned MCU lower-level controller further digitally filters and performs state evaluation on the absolute position signal conditioned and transmitted by the output flange force sensor 1 transmitter, and the MCU upper-level controller participates in the position closed-loop calculation process of the robot joint servo based on this absolute position signal, all of which are completed inside the MCU control board 13.

[0102] like Figure 5 and Figure 6 As shown, in order to further deepen the understanding, the transmission process between the output flange force sensor 1 and the robot joint servo absolute position signal can be further described as;

[0103] The output torque of the harmonic reducer 2 drives the robot servo joint to rotate, and the output flange force sensor 1 is connected to the joint elbow 19 through the mounting hole and the connector. This assembly connection relationship causes a reverse force on the output flange force sensor 1 when the robot servo joint rotates. This force causes the elastomer 21 inside the output flange force sensor 1 to produce a slight deformation. This slight deformation breaks the balance of the strain matrix bridge on the inner wall of the spoke 20 in the elastomer 21. Based on the vectorial principle of force, the robot joint will have forces of different sizes and directions when it rotates at different angles, and the corresponding strain matrix bridge will output different values, and the unbalanced output value of the strain matrix bridge is one-to-one corresponding to the rotation angle of the robot joint. Through strict physical parameter calibration, the absolute position signal of the robot joint angle is conditioned and transmitted by the output flange force sensor 1 transmitter, and the absolute position signal of the robot joint is transmitted to the MCU lower-level controller of the MCU control board 13. The MCU lower-level controller further digitally filters and evaluates the state of the absolute position signal of the output flange force sensor 1, and transmits the absolute position signal to the upper-level control of the MCU board of the MCU control board 13 to participate in the position closed-loop calculation of the robot joint servo;

[0104] In the present invention, the output flange force sensor 1 is advantageous for absolute position feedback of robot servo joints because it contains no microelectronic circuitry, exhibits strong resistance to harsh environments, possesses high radiation resistance, and, after rigorous physical parameter calibration, exhibits high absolute position accuracy. Therefore, it serves as a backup for absolute position feedback of robot joint servo joints in the present invention. Furthermore, to ensure the compactness and lightweight nature of the robot joints, the output flange force sensor 1 is designed in the form of an output flange. This not only functions as a flange for outputting joint torque, but also for identifying the absolute position of the robot joint output, thus balancing the dual functions of outputting joint torque and identifying the absolute position of the joint servo.

[0105] Therefore, the above-mentioned second resolver 9, absolute position encoder 10 and output flange force sensor 1 together constitute the redundant absolute position feedback of the robot joint servo, which is managed by the corresponding fault-tolerant method of the MCU control board 13, and jointly feeds back the absolute position of the robot joint servo, ensuring that the robot joint servo works in position mode and can dynamically follow the position and speed instructions issued by the main controller in real time.

[0106] like Figure 7 As shown, in the fault-tolerant electronic control method of the output flange force sensor 1, the output flange force sensor 1 is controlled by a separate power supply circuit, and the output flange force sensor 1 is in a cold standby state for a long time, and does not output absolute position feedback. When the hard decoding circuit and the soft decoding circuit of the second resolver 9 in the redundant absolute position feedback, and the absolute position encoder 10 all fail under a radiation environment, the output flange force sensor 1 starts working from the cold standby state and feeds back the absolute position of the robot servo joint to the MCU control board 13;

[0107] like Figure 7 As shown, the independent power supply circuit of the output flange force sensor 1 is mainly composed of a first N-type MOS transistor N1, a first P-type MOS transistor P1 and an operational amplifier follower circuit OP1;

[0108] In terms of the connection mode of the separate power supply circuit of the output flange force sensor 1, the gate of the first N-type MOS transistor N1 is connected to the MCU lower-layer controller on the MCU control board 13, the drain of the first N-type MOS transistor N1 is connected to the gate of the first P-type MOS transistor P1, the source of the first P-type MOS transistor P1 is connected to +V5, and the drain output of the first P-type MOS transistor P1 is connected to the positive input terminal of the operational amplifier follower circuit OP1 through a voltage divider resistor, and the output terminal +V7 of the operational amplifier follower circuit OP1 is directly connected to the transmitter of the output flange force sensor 1;

[0109] Among them, the working process of the independent power supply circuit of the output flange force sensor 1 can be further described as follows: the gate of the first N-type MOS tube N1 receives the arbitration signal sent by the MCU lower controller, indicating that the hard decoding circuit and the soft decoding circuit of the second resolver 9 and the absolute position encoder 10 have all failed in the radiation environment and are in an abnormal working state. The first N-type MOS tube N1 is turned on, the first P-type MOS tube P1 is turned on, and the output end +V7 of the operational amplifier follower circuit OP1 directly follows the input end +V5. At this time, +V5=+V7, +V7 directly supplies power to the output flange force sensor 1 transmitter separately, and the output flange force sensor 1 transmitter starts to work;

[0110] Among them, the MCU lower-level controller does not send an arbitration signal, indicating that the hard decoding circuit and the soft decoding circuit of the above-mentioned second resolver 9, as well as the absolute position encoder 10 are working normally, the first N-type MOS tube N1 is turned off, the first P-type MOS tube P1 is turned off, +V5=+V7=0, no external power supply, and the output flange force sensor 1 is in a no-power backup redundant cold standby state.

[0111] like Figure 8 As shown, the second resolver 9 in the redundant absolute position feedback is composed of a second resolver 9 hard decoding circuit and a second resolver 9 soft decoding circuit. The second resolver 9 hard decoding circuit is composed of a hard decoding chip circuit, a current buffer, and an MCU control board 13, while the second resolver 9 soft decoding circuit is composed of a signal conditioning circuit composed of a low-pass active filter and a second resolver 9 cold redundant power supply circuit.

[0112] like Figure 9 and Figure 10 As shown, the fault tolerance process of the second resolver 9 in the redundant absolute position feedback can be described as follows:

[0113] Step 1: When the second resolver 9 and the absolute position encoder 10 are working normally, they are used to detect and feed back the absolute position signal of the robot joint servo to the MCU control board 13. The second resolver 9 hard decoding circuit and the absolute position encoder 10 are directly powered by the low-voltage power supply board 11. +V1 is the hard decoding chip circuit and current buffer in the second resolver 9 hard decoding circuit, and +V2 is the power supply for the absolute position encoder 10.

[0114] Step 2: The MCU lower-layer controller on the MCU control board 13 does not send an arbitration signal to the cold redundant power supply circuit of the second resolver 9, and the soft decoding circuit of the second resolver 9 does not start. At this time, the first N-type MOS transistor N1 is turned off, the first P-type MOS transistor P1 is turned off, and the drain output end of the first P-type MOS transistor P1 does not supply power to the outside. The soft decoding circuit of the second resolver 9 is always in a cold standby state without power supply;

[0115] Step 3: When a radiation fault effect occurs in the hard decoding chip circuit of the second resolver 9 in the redundant absolute position feedback of the robot joint servo, the MCU lower-layer controller on the MCU control board 13 sends an arbitration signal to the cold redundant power supply circuit of the second resolver 9, and the soft decoding circuit of the second resolver 9 starts to start;

[0116] Step 4: After the cold redundant power supply circuit of the second resolver 9 receives the arbitration signal from the MCU control board 13, the first N-type MOS transistor N1 and the first P-type MOS transistor P1 in the cold redundant power supply circuit of the second resolver 9 are turned on, and the drain output end of the first P-type MOS transistor P1 directly supplies independent power to the signal conditioning circuit in the soft decoding circuit of the second resolver 9;

[0117] Step 5: The startup of the soft decoding circuit and independent power supply of the second resolver 9 are completed, the switching of the backup cold redundancy work is completed, the absolute position of the robot joint servo is detected, and the absolute position of the robot joint servo is fed back to the MCU control board 13, thereby realizing the fault tolerance of the second resolver 9.

[0118] like Figure 11 As shown, the output flange force sensor 1, the second resolver 9 and the absolute position encoder 10 in the redundant absolute position feedback adopt a gradient composite fault-tolerant method, which can effectively manage the hardware circuits of the output flange force sensor 1, the second resolver 9 and the absolute position encoder 10 in the redundant absolute position feedback;

[0119] The gradient composite fault-tolerance method considers the full working process of the robot joint servo in a radiation environment, including high-precision operation, non-high-precision operation, and emergency return. When any one or more absolute position feedback circuits experience radiation fault effects at the same time under all working conditions, the mutual fault tolerance strategy between the output flange force sensor 1, the second resolver 9, and the absolute position encoder 10 is considered. The gradient composite fault-tolerance strategy process of redundant absolute position feedback can be described as follows:

[0120] Step 1: When the robot joint servo is performing non-high-precision operations such as entering and exiting the field and initializing the posture in a radiation environment, the MCU control board 13 will automatically switch to the hard decoding of the second resolver 9. The accuracy of the hard decoding of the second resolver 9 can meet the non-precision operation. During this step, the soft decoding circuit of the second resolver 9 is not started, and the soft decoding of the second resolver 9 is always in a backup cold redundancy state;

[0121] Step 2: When the robot joint servo starts high-precision operation, the MCU control board 13 will automatically start the absolute position encoder 10 and the second resolver 9 and the second resolver 9 hard decoding circuit. The lower controller of the MCU control board 13 simultaneously reads the absolute position data of the absolute position encoder 10 and the absolute position data of the second resolver 9 hard decoding circuit. The lower controller of the MCU control board 13 fuses the absolute position data of the absolute position encoder 10 and the absolute position data of the second resolver 9 hard decoding circuit through a data fusion algorithm to obtain a more accurate robot joint servo absolute position signal. The upper controller of the MCU control board 13 uses the fused absolute position data signal as the final position closed-loop signal of the robot joint servo to participate in the closed-loop operation of the robot joint servo position loop. During this step, the soft decoding circuit of the second resolver 9 is not started, and the soft decoding of the second resolver 9 is always in a backup cold redundant state.

[0122] Step 3: When the robot joint servo operates normally with high precision in a radiation environment, the hard decoding chip circuit of the second resolver 9 and the absolute position encoder 10 work simultaneously and serve as the main decoding circuit. When the absolute position encoder 10 experiences a radiation fault effect, the soft decoding circuit of the second resolver 9 starts to start. At this time, the soft decoding and hard decoding circuits of the second resolver 9 continue to provide absolute position feedback for the robot joint servo.

[0123] Step 4: As the working time increases, the cumulative effect of radiation continues to increase. When the second resolver 9 hard decoding chip circuit has a radiation failure effect, the MCU control board 13 starts the output flange force sensor 1, and the output flange force sensor 1 continues to provide absolute position feedback for the robot joint servo. At this time, the robot can only passively return to the non-high-precision operation state in an emergency;

[0124] Step 5: All redundant absolute position feedback hardware circuits of the robot joint servo fail simultaneously, and the MCU control board 13 adopts variable frequency speed regulation operation, adopts absolute position open loop, and performs emergency return non-high-precision operation in the current loop and speed loop working mode of the inverter;

[0125] The accuracy of the four methods of obtaining the absolute position of the robot joint servo, namely the absolute position encoder 10, the hard decoding of the second resolver 9, the soft decoding of the second resolver 9 and the output flange force sensor 1, decreases successively. When the gradient composite fault-tolerant strategy manages the above hardware circuits, combined with the operating conditions of the robot joint servo, the priority is always given to the use of hardware precision absolute position feedback. The implementation and development of the above gradient composite fault-tolerant management strategy can at least ensure that the joint movement will not be stuck, no matter what working state the robot joint servo absolute position feedback circuit is in, and can significantly improve the service life of the robot joint servo in extreme environments such as radiation.

[0126] like Figure 12 and 13 As shown, the redundant incremental position feedback in the robot joint servo redundant position feedback electronic control unit is composed of a first resolver 7 and an incremental position encoder 17;

[0127] The composition and fault tolerance process of the first resolver 7 in the redundant incremental position feedback are exactly the same as the composition and fault tolerance process of the second resolver 9 in the redundant absolute position feedback, and will not be repeated here;

[0128] The gradient composite fault-tolerant strategy between the first resolver 7 and the incremental position encoder 17 of the redundant incremental position feedback is the same as the first step, the second step, and the third step corresponding to the composite fault-tolerant strategy process between the second resolver 9 and the absolute position encoder 10 in the redundant absolute position feedback, and will not be repeated here;

[0129] The difference of the redundant incremental position feedback is that: when the redundant incremental position feedback first resolver 7 and the incremental position encoder 17 all have radiation fault effects, the robot joint servo torque motor 4 will not be able to start normally. At this time, based on the saturated salient pole effect of the robot joint servo torque motor, the MCU control board 13 will automatically switch to the sensorless high-frequency injection starting algorithm. After the robot joint servo torque motor is started, the state observer virtual sensor constructed by the MCU control board 13 is used to estimate the incremental position signal of the servo torque motor 4 based on the output state of the state observer virtual sensor. At the same time, the incremental position signal of the robot joint servo torque motor 4 is fed back to the MCU control board 13, and the incremental position signal participates in the speed closed-loop control of the MCU control board 13.

[0130] The voltages required for the redundant incremental position feedback and the redundant absolute position feedback in the robot joint servo redundant position feedback electronic control unit are obtained from the low-voltage power supply board 11, and the acquisition method adopts step-by-step power supply;

[0131] The cold redundant power supply circuit of the first resolver 7 for redundant incremental position feedback, the separate power supply circuit of the output flange force sensor 1 for redundant absolute position feedback, and the cold redundant power supply circuit of the second resolver 9 are all controlled by the MCU lower layer of the MCU control board 13.

[0132] In the present invention, the mechanical structure and assembly, circuit system architecture, power supply method, cold redundant power supply circuit, and gradient composite fault-tolerant strategy for managing redundant position feedback corresponding to the redundant incremental position feedback and redundant absolute position feedback in the above-mentioned robot joint servo position feedback are not only applicable to robot joint servo, but also to intelligent tracked chassis with position feedback, CNC machine tools, radars and other equipment with high-precision position feedback.

[0133] The above is only an embodiment of the present invention, and common sense such as the specific structure and characteristics of the scheme are not described in detail here. For those skilled in the art, it is obvious that the present invention is not limited to the details of the above exemplary embodiments, and the present invention can be implemented in other specific forms without departing from the spirit or basic characteristics of the present invention. Therefore, from any point of view, the embodiments should be regarded as exemplary and non-restrictive. The scope of the present invention is defined by the appended claims rather than the above description, and it is intended that all changes that fall within the meaning and scope of the equivalent elements of the claims are included in the present invention. Any figure mark in the claims should not be regarded as limiting the claim involved.

Claims

1. A robot joint servo composite fault-tolerant redundant position feedback and its electronic control method, comprising a robot joint servo mechanical actuator unit and a robot joint servo redundant position feedback electronic control unit, characterized in that: The robot joint servo mechanical execution unit includes a servo torque motor (4), a harmonic reducer (2), a reduction shaft (18), a joint transition elbow (19), an output flange force sensor (1), and a robot joint housing (23); The servo torque motor (4), the harmonic reducer (2), the servo torque motor output disc sleeve (6), the reduction shaft (18), the joint brake (8), the brake disc (15) and the brake fixing member (16) all have a central hole and are coaxial with the central axis of the robot joint housing (23); The reduction shaft (18) is located inside the robot joint housing (23), and the reduction shaft (18) has a two-step shaft, wherein the diameter of the first step shaft is larger than the diameter of the second step shaft; the shaft end of the first step shaft has an output flange force sensor (1), and the output flange force sensor (1) is connected to the joint transition elbow (19) through a mounting hole and a connecting piece; The harmonic reducer (2), the servo torque motor (4), the servo torque motor output disc sleeve (6), the joint brake (8), the brake disc (15) and the brake fixing member (16) are sequentially inserted and installed from the output flange force sensor (1) of the first step shaft of the reduction shaft (18) toward the second step shaft; The servo torque motor output disc sleeve (6) is connected to the servo torque motor (4) through the mounting hole and the connecting piece, and the second step shaft on the reduction shaft (18) passes through the servo torque motor output disc sleeve (6), ensuring that there is a gap between the servo torque motor output disc sleeve (6) and the reduction shaft (18), so that the power transmission between the reduction shaft (18) and the servo torque motor output disc sleeve (6) is independent of each other and does not interfere with each other; The joint brake (8), the brake disc (15) and the brake fixing member (16) are fitted onto the servo torque motor output disc sleeve (6) through interference fit, ensuring that the speed torque and incremental position signal of the servo torque motor (4) are directly transmitted to the servo torque motor output disc sleeve (6) and the joint brake (8); The robot joint servo redundant position feedback electronic control unit comprises redundant incremental position feedback, redundant absolute position feedback, a low voltage power supply board (11), a servo drive board (12), an MCU control board (13) and a sensor perception board (14); The redundant incremental position feedback in the robot joint servo redundant position feedback electronic control unit includes a first resolver (7) and an incremental position encoder (17); In order to feed back the incremental position of the robot joint servo to the MCU control board (13), the first resolver (7) and the incremental position encoder (17) must be installed at the second step shaft of the reduction shaft (18), and the first resolver (7) and the incremental position encoder (17) must be interference-fitted with the servo torque motor output disc sleeve (6), ensuring that the torque output of the servo torque motor rotor (5) is transmitted to the first resolver (7) and the incremental position encoder (17) through the servo torque motor output disc sleeve (6), ensuring that the first resolver (7) and the incremental position encoder (17) jointly detect the incremental position signal of the output end of the servo torque motor rotor (5), and feed back the incremental position signal to the MCU control board (13), and the incremental position signal participates in the closed-loop operation of the speed loop and the current loop followed by the robot joint servo.

2. The robot joint servo composite fault-tolerant redundant position feedback and its electronic control method according to claim 1, characterized in that: When the robot servo joint is powered off and shut down, the joint brake (8) receives a command from the MCU control board (13) and automatically powers on and starts. The joint brake (8) tightly attracts the brake disc (15) through electromagnetic force, thereby achieving emergency braking of the servo torque motor (4). At this time, the first resolver (7) and the incremental position encoder (17) in the redundant incremental position feedback stop feeding back incremental position signals to the MCU control board (13).

3. The robot joint servo composite fault-tolerant redundant position feedback and its electronic control method according to claim 1, characterized in that: The low-voltage power supply board (11) provides normal operating voltage for the first rotary transformer (7) and the incremental position encoder (17) of redundant incremental position feedback in the robot joint servo redundant position feedback electric control unit; the servo drive board (12) provides drive for the entire robot joint servo, thereby driving the first rotary transformer (7) and the incremental position encoder (17) to rotate; the MCU control board (13) is used to receive the robot incremental position signal fed back by the first rotary transformer (7) and the incremental position encoder (17); the sensor perception board (14) internally integrates the signal conditioning circuit of the first rotary transformer (7) and the incremental position encoder (17), thereby ensuring that the signals of the first rotary transformer (7) and the incremental position encoder (17) are not distorted when they are working.

4. The robot joint servo composite fault-tolerant redundant position feedback and its electronic control method according to claim 1, characterized in that: The redundant absolute position feedback in the redundant position feedback electronic control unit of the robot joint servo comprises an output flange force sensor (1), a second resolver (9) and an absolute position encoder (10); In order to feed back the absolute position of the robot joint servo to the MCU control board (13), the second rotary transformer (9) and the absolute position encoder (10) must be interference-fitted at the second stepped shaft of the reduction shaft (18), and the output flange force sensor (1) must be interference-fitted at the first stepped shaft of the reduction shaft (18). The output flange force sensor (1) is connected to the joint transition elbow (19) through the mounting hole and the connector. The joint transition elbow (19) is connected to the robot connecting rod (24), ensuring that the output flange force sensor (1) detects the absolute position of the joint transition elbow (19) and the robot connecting rod (24). The absolute position of the joint transition elbow (19) and the robot connecting rod (24) is also the absolute position of the robot joint servo output. The harmonic reducer input disc (3) is connected to the servo torque motor rotor (5) through the mounting hole and the connecting piece, and receives the torque of the servo torque motor rotor (5); the harmonic reducer (2) is connected to the harmonic reducer input disc (3) through the mounting hole and the connecting piece; the first step shaft of the reduction shaft (18) is connected to the harmonic reducer (2) by interference fitting; the above-mentioned assembly relationship ensures that the torque of the servo torque motor rotor (5) is transmitted to the reduction shaft (18) after being decelerated and torque-increased by the harmonic reducer (2); The second step shaft of the reduction shaft (18) is interference-fitted with a second resolver (9) and an absolute position encoder (10). The torque output of the harmonic reducer (2) drives the second resolver (9) and the absolute position encoder (10) to rotate together, and the two together detect the absolute position of the robot joint servo output. The interference fit positions of the second resolver (9), the absolute position encoder (10), and the output flange force sensor (1) on the first step shaft and the second step shaft of the reduction shaft (18) cannot be replaced; The electromechanical assembly relationship of the redundant absolute position feedback ensures that the second resolver (9), the absolute position encoder (10) and the output flange force sensor (1) all detect the absolute position of the robot joint servo and feed back the absolute position of the robot joint servo to the MCU control board (13).

5. The robot joint servo composite fault-tolerant redundant position feedback and its electronic control method according to claim 1 or claim 4, characterized in that: The low-voltage power supply board (11) provides normal operating voltage for the second rotary transformer (9), the absolute position encoder (10) and the output flange force sensor (1) of the redundant absolute position feedback in the robot joint servo redundant position feedback electronic control unit; the servo drive board (12) provides drive for the entire robot joint servo, thereby driving the second rotary transformer (9), the absolute position encoder (10) and the output flange force sensor (1) to rotate; the MCU control board (13) is used to receive the robot absolute position signal fed back by the second rotary transformer (9), the absolute position encoder (10) and the output flange force sensor (1); the sensor sensing board (14) internally integrates the signal conditioning circuit of the second rotary transformer (9), the absolute position encoder (10) and the output flange force sensor (1), thereby ensuring that the signals of the second rotary transformer (9), the absolute position encoder (10) and the output flange force sensor (1) are not distorted when they are working.

6. The robot joint servo composite fault-tolerant redundant position feedback and its electronic control method according to claim 4, characterized in that: The output flange force sensor (1) in the redundant absolute position feedback comprises an output flange force sensor (1) body, an output flange force sensor (1) transmitter and an output flange force sensor (1) rear end; The output flange force sensor (1) comprises a spoke (20), an elastic body (21) and a strain gauge (22). The strain gauge (22) is bonded and mounted in groups on the inner wall of the spoke (20) of the elastic body (21). The multiple groups of strain gauges form a strain matrix bridge. The strain matrix bridge can sense the force / torque applied to the robot joint servo during rotation in real time. The output flange force sensor (1) transmitter comprises a signal conditioning circuit and an AD converter, and is used for amplifying and conditioning the strain matrix bridge output signal of the output flange force sensor (1) body and actively filtering the signal, and converting the signal into a digital signal for transmission to the MCU control board (13); The rear end of the output flange force sensor (1) includes an MCU control board, and the MCU lower layer controller and the MCU upper layer controller are respectively integrated into the MCU control board (13) through integrated circuit technology; The MCU lower-layer controller further performs digital filtering and state evaluation on the absolute position signal conditioned and transmitted by the output flange force sensor (1) transmitter, and the MCU upper-layer controller participates in the position closed-loop calculation process of the robot joint servo based on the absolute position signal, all of which are completed inside the MCU control board (13); The output flange force sensor (1) is in a cold standby state for a long time under the control of a separate power supply circuit, and does not perform absolute position feedback output; When the hard decoding circuit and the soft decoding circuit of the second resolver (9) in the redundant absolute position feedback and the absolute position encoder (10) all fail, the output flange force sensor (1) starts working from a cold standby state and feeds back the absolute position of the robot servo joint to the MCU control board (13).

7. The robot joint servo composite fault-tolerant redundant position feedback and its electronic control method according to claim 6, characterized in that: The output flange force sensor (1) has a separate power supply circuit comprising a first N-type MOS transistor N1, a first P-type MOS transistor P1 and an operational amplifier follower circuit OP1; In terms of connection mode, the separate power supply circuit of the output flange force sensor (1) has a gate of the first N-type MOS transistor N1 connected to the MCU lower controller on the MCU control board (13), a drain of the first N-type MOS transistor N1 connected to the gate of the first P-type MOS transistor P1, a source of the first P-type MOS transistor P1 connected to the low-voltage power supply board (11), a drain output of the first P-type MOS transistor P1 connected to the positive input end of the operational amplifier follower circuit OP1 through a voltage divider resistor, and an output end of the operational amplifier follower circuit OP1 directly connected to the transmitter of the output flange force sensor (1); The gate of the first N-type MOS tube N1 receives the arbitration signal sent by the MCU lower controller, indicating that the hard decoding circuit and the soft decoding circuit of the second rotary transformer (9), as well as the absolute position encoder (10) are all faulty and in an abnormal working state. The first N-type MOS tube N1 is turned on, the first P-type MOS tube P1 is turned on, the output end of the operational amplifier follower circuit OP1 directly follows the input end, the output end of the operational amplifier follower circuit OP1 directly supplies power to the output flange force sensor (1) transmitter, and the output flange force sensor (1) transmitter starts to work; The MCU lower-layer controller does not send an arbitration signal, indicating that the hard decoding circuit and the soft decoding circuit of the second resolver (9) and the absolute position encoder (10) are working normally, the first N-type MOS transistor N1 is turned off, the first P-type MOS transistor P1 is turned off, and the output flange force sensor (1) is in a no-power backup redundant cold standby state.

8. The robot joint servo composite fault-tolerant redundant position feedback and its electronic control method according to claim 4, characterized in that: The second resolver (9) in the redundant absolute position feedback includes a second resolver (9) hard decoding circuit and a second resolver (9) soft decoding circuit, wherein the second resolver (9) hard decoding circuit includes a hard decoding chip circuit, a current buffer and an MCU control board (13), and the second resolver (9) soft decoding circuit includes a signal conditioning circuit and a second resolver (9) cold redundant power supply circuit; The fault tolerance process of the second resolver (9) in the redundant absolute position feedback can be described as: Step 1: When the second resolver (9) and the absolute position encoder (10) are working normally, they are used to detect and feed back the absolute position signal of the robot joint servo to the MCU control board (13), and the second resolver (9) hard decoding circuit and the absolute position encoder (10) are directly powered by the low-voltage power supply board (11); Step 2: The MCU lower layer controller on the MCU control board (13) does not send an arbitration signal to the cold redundant power supply circuit of the second resolver (9), and the soft decoding circuit of the second resolver (9) does not start. At this time, the first N-type MOS transistor N1 is turned off, the first P-type MOS transistor P1 is turned off, the drain output end of the first P-type MOS transistor P1 does not supply power to the outside, and the soft decoding circuit of the second resolver (9) is always in a cold standby state without power supply; Step 3: When a fault occurs in the hard decoding chip circuit of the second resolver (9) in the redundant absolute position feedback, the MCU lower layer controller on the MCU control board (13) sends an arbitration signal to the cold redundant power supply circuit of the second resolver (9), and the soft decoding circuit of the second resolver (9) starts to start; Step 4: After the cold redundant power supply circuit of the second resolver (9) receives the arbitration signal from the MCU control board (13), the first N-type MOS transistor N1 in the cold redundant power supply circuit of the second resolver (9) is turned on, the first P-type MOS transistor P1 is turned on, and the drain output end of the first P-type MOS transistor P1 directly supplies independent power to the signal conditioning circuit in the soft decoding circuit of the second resolver (9); Step 5: The second resolver (9) soft decoding circuit startup and independent power supply are completed, the cold redundant work switching is completed, the robot joint servo absolute position is detected, and the robot joint servo absolute position is fed back to the MCU control board (13), thereby realizing the fault tolerance of the second resolver (9).

9. The robot joint servo composite fault-tolerant redundant position feedback and its electronic control method according to claim 4, characterized in that: The output flange force sensor (1), the second resolver (9) and the absolute position encoder (10) in the redundant absolute position feedback adopt a gradient composite fault-tolerant strategy, which can effectively manage the output flange force sensor (1), the second resolver (9) and the absolute position encoder (10) in the redundant absolute position feedback; The gradient composite fault-tolerant strategy takes into account the service process of the robot joint servo in all working conditions, including high-precision operation, non-high-precision operation, and emergency return. When any one or more absolute position feedbacks fail at the same time under all working conditions, the mutual fault-tolerant strategy between the output flange force sensor (1), the second resolver (9) and the absolute position encoder (10) is adopted. The fault-tolerant process can be described as follows: Step 1: When the robot joint servo is in non-high-precision operation, the MCU control board (13) will automatically switch to the hard decoding of the second resolver (9), relying on the hard decoding of the second resolver (9) to meet the non-precision operation. During this process, the soft decoding circuit of the second resolver (9) is not started, and the soft decoding of the second resolver (9) is always in a backup cold redundant state; The second step: when the robot joint servo is in high-precision operation, the MCU control board (13) automatically starts the absolute position encoder (10) and the second resolver (9) and the second resolver (9) hard decoding circuit, the lower controller of the MCU control board (13) simultaneously reads the absolute position data of the absolute position encoder (10) and the second resolver (9) hard decoding absolute position data, the lower controller of the MCU control board (13) fuses the absolute position data of the absolute position encoder (10) and the absolute position data of the second resolver (9) hard decoding circuit through a data fusion algorithm, and obtains a robot joint servo absolute position signal with higher precision, the upper controller of the MCU control board (13) uses the fused absolute position data signal as the final position closed-loop signal of the robot joint servo, and participates in the closed-loop operation of the robot joint servo position loop, during which the soft decoding circuit of the second resolver (9) is not started, and the soft decoding of the second resolver (9) is always in a backup cold redundant state; The third step: when the robot joint servo operates normally with high precision, the hard decoding chip circuit of the second resolver (9) and the absolute position encoder (10) work simultaneously and serve as the main decoding circuit. When the absolute position encoder (10) fails, the soft decoding circuit of the second resolver (9) starts to start. At this time, the soft decoding and hard decoding circuits of the second resolver (9) continue to provide absolute position feedback for the robot joint servo. Step 4: As the working time increases, when the second resolver (9) hard decoding chip circuit fails, the MCU control board (13) starts the output flange force sensor (1), and the output flange force sensor (1) continues to provide absolute position feedback for the robot joint servo. At this time, the robot is passively in an emergency return non-high-precision operation state; Step 5: All redundant absolute position feedback hardware circuits of the robot joint servo fail at the same time, and the MCU control board (13) adopts variable frequency speed regulation operation and absolute position open loop. At this time, the robot is passively in an emergency return non-high-precision operation state.

10. The robot joint servo composite fault-tolerant redundant position feedback and its electronic control method according to claim 1, characterized in that: The redundant incremental position feedback in the robot joint servo redundant position feedback electronic control unit is composed of a first resolver (7) and an incremental position encoder (17); When the redundant incremental position feedback first resolver (7) and the incremental position encoder (17) all have fault effects, the MCU control board (13) will automatically switch to the non-sensing high-frequency injection startup algorithm, the MCU control board (13) will construct a state observer virtual sensor to output the state, and the state estimates the incremental position signal of the servo torque motor (4). At the same time, the incremental position signal is fed back to the MCU control board (13), and the incremental position signal participates in the speed closed-loop control of the MCU control board (13).

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