A Space Robotic Arm Full-State Air-Floating Ground Test System

Abstract

This invention relates to a full-state air-float ground testing system for a space robotic arm, comprising a joint decoupling air-float device, a mirror-image robotic arm, a digital twin robotic arm, and a six-degree-of-freedom target simulator. The joint decoupling air-float device decouples the space robotic arm and supports it using air float technology, offsetting or partially offsetting the load torque caused by gravity at the joints of the space robotic arm. The mirror-image robotic arm performs six-dimensional motion in three-dimensional space on the ground according to the drive commands of the load motor, realizing full-loop testing of the space robotic arm's spatial target capture. The six-degree-of-freedom target simulator is driven by an industrial robotic arm to simulate the motion characteristics of the captured target relative to the space robotic arm's base. The digital twin robotic arm realizes the functions of real-time calculation of the space robotic arm's dynamics, three-dimensional display, and calculation of the target's relative pose. This invention can achieve complete reproduction of the on-orbit target capture and control of the robotic arm, with high experimental accuracy, and can meet the high-dynamic ground testing requirements of space robotic arms.

Description

Technical Field

[0001] This invention belongs to the field of ground testing of space robots and relates to a full-state air-floating ground testing system for a space robotic arm. Background Technology

[0002] Advances in science and technology have propelled human activity in space to greater heights. On-orbit servicing of spacecraft, including capture, maintenance, refueling, and module upgrades, is a key area of ​​future development in the aerospace field. Astronauts face extremely high risks during extravehicular activities (EVAs) for on-orbit servicing missions; using robotic arms to perform these tasks in place of astronauts can mitigate these risks and control costs, making them highly practical. To ensure the successful on-orbit execution of these robotic arms, thorough ground-based experiments are essential. Conducting full-state experiments under ground gravity conditions to test the on-orbit microgravity motion planning and control algorithms of these robotic arms is a hot research topic in the field of space robotics. Currently, there are six main methods for conducting ground-based experiments on space robots: microgravity simulation experiments based on free fall motion, microgravity simulation experiments based on parabolic flight, water buoyancy, air buoyancy, wire-based counterweight methods, and hardware-in-the-loop hybrid experimental methods.

[0003] Free fall and parabolic flight methods can simulate weightlessness with high precision, but they are time-consuming and costly, generally used for astronaut training and not suitable for ground-based experiments on space robotic arms. Water flotation relies on the buoyancy of water to counteract gravity, thus simulating the microgravity environment of space. While not time-limited, it introduces water viscous damping and requires additional waterproofing measures for the tested equipment, and is generally not used for ground-based experiments on space robotic arms. Air flotation uses air bearings to form a micrometer-scale air film to counteract friction and support the object under test, completing microgravity dynamics testing. This method is not time-limited, is inexpensive, and is commonly used for ground-based experiments on GNC systems of satellites and spacecraft. However, for ground-based experiments on multi-degree-of-freedom space robotic arms, air flotation can only perform planar 2D microgravity simulations and cannot be used for Cartesian space-based experiments on robotic arms. The wire-suspension counterweight method suspends the robotic arm using wires and counterweights to counteract gravity, achieving balance. Alternatively, an active tension control method uses a motor to control the tension of the wires to counteract the weight of the object under test. This method can simulate microgravity environments dynamically for extended periods and is relatively low-cost, making it a common ground-based experimental method for space robots. However, due to significant dynamic disturbances caused by the wire suspension, the experimental speed is generally slow and cannot meet the high-dynamic ground-based experimental requirements of space robotic arms. The hardware-in-the-loop hybrid experimental method uses a space robotic arm dynamics model to drive two or more industrial robotic arms in a floating state at their ends. This method is generally used for on-orbit grasping or contact manipulation algorithm research, but it cannot be used for direct ground testing of physical space robotic arms providing on-orbit services. Summary of the Invention

[0004] The technical problem solved by this invention is to overcome the shortcomings of the prior art and propose a full-state air-floating ground test system for space robotic arms.

[0005] The solution of the present invention is:

[0006] A full-state air-float ground test system for a space robotic arm includes a joint decoupling air-float device, a mirror robotic arm, a digital twin robotic arm, and a six-degree-of-freedom target simulator;

[0007] Joint decoupling air-float device: The space robot arm is decoupled into a shoulder joint assembly, an elbow joint assembly, and a wrist joint assembly; and the decoupled space robot arm is supported by air-float, which cancels or partially cancels the load torque caused by gravity on the joints of the space robot arm, so as to realize the coordinated movement of the joints of the space robot arm.

[0008] Mirror robotic arm: It performs six-dimensional motion in three-dimensional space on the ground according to the drive command of the load motor. Its motion state is consistent with the motion state of each joint of the space robotic arm, realizing the full-loop test of the space robotic arm grasping the target in space; the drive command of the load motor is generated according to the real-time motion state of the joints of the space robotic arm.

[0009] Six-DOF target simulator: driven by an industrial robotic arm, it simulates the motion characteristics of the target being captured relative to the base of the space robotic arm;

[0010] Digital twin robotic arm: Enables real-time calculation of the dynamics of a space robotic arm, 3D display, and calculation of the relative pose of the target.

[0011] Preferably, the spatial robotic arm includes seven joints: elbow joint 4 is fixed to an elbow fixing connector; the upper part of elbow joint 4 is connected to shoulder joint 3; shoulder joint 3 is connected to shoulder joint 2 via a shoulder arm; shoulder joint 2 is connected to shoulder joint 1; the rotation axis of shoulder joint 2 is perpendicular to the rotation axis of shoulder joint 1; the lower part of elbow joint 4 is connected to wrist joint 5; wrist joint 5 is connected to wrist joint 6 via a wrist arm; wrist joint 6 is connected to wrist joint 7; and wrist joint 7 is connected to an end effector.

[0012] The shoulder joint (3 joints), shoulder arm joint (2 joints), and shoulder joint (1 joint) form a "shoulder joint assembly"; the elbow joint (4 joints) forms a "elbow joint assembly"; and the wrist joint (5 joints), wrist arm joint (6 joints), and wrist joint (7 joints) form a "wrist joint assembly".

[0013] Preferably, the joint decoupling air flotation device includes a planar air flotation device and an air flotation base.

[0014] Preferably, one test state for the planar air flotation device is as follows:

[0015] The elbow fixing connector of the space robot arm is installed on the air-floating base, realizing the decoupling of the seven-degree-of-freedom space robot arm into "3+1+3" degrees of freedom. At this time, two air-floating devices are required to support the shoulder arm and the wrist arm respectively. After decoupling, the "shoulder joint assembly" includes 3 degrees of freedom, the "elbow joint assembly" includes 1 degree of freedom, and the "wrist joint assembly" includes 3 degrees of freedom, realizing the complete experimental verification of the seven degrees of freedom of the robot arm on the ground and the actual rotation in space.

[0016] Preferably, one test state of the planar air flotation device is as follows: the shoulder joint 1 of the space robot arm is installed on the air flotation base through the shoulder fixing connector. At this time, three planar air flotation devices are required to support the shoulder arm, elbow joint 4, and wrist arm respectively, so as to realize the complete test verification of the rotation of the seven-degree-of-freedom space robot arm joints 2, 4, 5, 6, and 7 in space.

[0017] Preferably, shoulder joint 1 has no external load, shoulder joint 2 bears the load of shoulder joint 1, and shoulder joint 3 bears the load of shoulder joint 1, shoulder joint 2, and shoulder arm. A slip ring mechanism is designed on the shoulder arm to balance the load bending moment of shoulder joint 3 and elbow joint 4, so that shoulder joint 3 and elbow joint 4 hardly bear the load torque generated by the weight of shoulder joint 1 and shoulder joint 2. A slip ring mechanism is designed on the wrist arm to balance the load bending moment of wrist joint 6, wrist joint 7, and end effector, so that wrist joint 5 and elbow joint 4 hardly bear the load torque generated by the weight of wrist joint 6, wrist joint 7, and end effector.

[0018] Preferably, the load on the wrist 7 joint is only the end effector, and the load on the wrist 6 joint is a combination of the wrist 7 joint and the end effector.

[0019] Preferably, the kinematic parameters and shape parameters related to collision detection of the mirror robotic arm are consistent with those of the space robotic arm; the mirror robotic arm is driven by the joint motion state of the space robotic arm, accurately reproduces the Cartesian motion state of the end effector of the space robotic arm, and directly drives the hand-eye camera to complete the dynamic measurement of the target pose.

[0020] Preferably, a space dynamics compensation control method is used to calculate the residual torque error of the ground test system in real time, thereby eliminating the ground gravity interference error that is not completely offset by the joint decoupling air flotation device.

[0021] Preferably, the spatial dynamics compensation control method is implemented using the following steps:

[0022] The first step is to establish an on-orbit dynamic model of the fixed-base space manipulator based on its dynamic parameters, and to calculate the joint torque τ required for the j-th joint by inputting the motion angle, angular velocity, and angular acceleration of each joint. jm j = 1, 2, 3, 4, 5, 6, 7;

[0023] The second step involves installing the elbow fixing connector of the space robotic arm onto the air-floating base, inputting the same motion angles, angular velocities, and angular accelerations for each joint as in the first step, and recording the joint torque sensor measurement value τ of the j-th joint of the space robotic arm in real time. ja ;

[0024] The third step involves selecting the motion angles, angular velocities, and angular acceleration trajectories of each joint of the space robotic arm corresponding to N task segments, and calculating the joint torque τ required for the j-th joint in each task segment according to the first and second steps respectively. jm1 ,τ jm2 ...τ jmN And record the joint torque sensor measurement value τ of the j-th joint in each task segment. ja1 ,τ ja2 ...τ jaN Where N≥5;

[0025] Fourth step: Calculate the normalized torque compensation value Δτ of the j-th joint using the following formula. js :

[0026]

[0027] Among them, T s T is the sampling frequency. i Let k be the duration of the i-th task segment, where k = [T]. i / T s [], [] represents the integer part, τ jmit and τ jait These are the calculated joint torque and the joint torque measured by the torque sensor for the j-th joint of the space robotic arm during the t-th sampling period of the i-th task, respectively. jit Let be the joint motion angle of the j-th joint during the t-th sampling period of the i-th task, in radians;

[0028] Fifth, the normalized torque compensation value of the j-th joint is used to perform dynamic compensation on the measured joint torque sensor value of the j-th joint. After compensation, the ground test torque value of the j-th joint is τ. je =τ ja +q j Δτ js , where q j Let be the motion angle of the j-th joint of the current space robotic arm.

[0029] The beneficial effects of this invention compared to the prior art are:

[0030] (1) The space manipulator full-state air-float ground test system proposed in this invention includes a joint decoupling air-float device, a mirror manipulator, a digital twin manipulator, and a six-degree-of-freedom target simulator. It can realize the complete reproduction of the manipulator's on-orbit target capture and control. The ground air-float test, the mirror manipulator test, and the digital twin manipulator test are used for comparison and verification of the correctness and rationality of various data of the space manipulator's on-orbit task execution.

[0031] (2) This invention achieves complete replication of the joint motion of a space robot arm in a ground environment by using a joint decoupling air-float test method. Through a space dynamics compensation control method, it can calculate the residual torque error of the ground test system in real time, eliminating ground gravity interference errors that are not completely offset by the joint decoupling air-float device. The test has high accuracy and can meet the high-dynamic ground test requirements of space robots. Attached Figure Description

[0032] Figure 1 Flowchart of dynamic compensation control algorithm;

[0033] Figure 2 This is a schematic diagram of the space robotic arm of the present invention. Detailed Implementation

[0034] The invention will now be further described with reference to the accompanying drawings.

[0035] The present invention provides a full-state air-float ground test system for a space robotic arm, comprising a joint decoupling air-float device, a mirror robotic arm system, a digital twin robotic arm, and a 6-DOF target simulator, enabling performance testing of physical products of the space robotic arm system, such as the space robotic arm, robotic arm controller, and hand-eye camera.

[0036] The joint decoupling air-float device decouples the space robotic arm into a shoulder joint assembly, an elbow joint assembly, and a wrist joint assembly; and supports the decoupled space robotic arm by air-floatation, offsetting or partially offsetting the load torque caused by gravity on the joints of the space robotic arm, thereby providing load reduction support for the space robotic arm and realizing the coordinated movement of the seven joints of the robotic arm.

[0037] The mirror robotic arm is driven by a high-load motor and can achieve six-dimensional motion in three-dimensional space on the ground. Its kinematic parameters and key shape parameters for collision detection are consistent with those of the space robotic arm.

[0038] The mirror robotic arm is driven by the joint motion state of the space robotic arm, accurately reproduces the Cartesian motion state of the end effector of the space robotic arm, and directly drives the hand-eye camera to complete the dynamic measurement of the target pose.

[0039] The test target was a six-degree-of-freedom target simulator, driven by an industrial robotic arm, to simulate the motion characteristics of the captured target relative to the base of the space robotic arm.

[0040] Digital twin robotic arms enable functions such as real-time calculation of spatial robotic arm dynamics, 3D display, and calculation of target relative pose.

[0041] This invention enables the decoupling of the joint space and Cartesian space motion of a space robotic arm under ground gravity environment, supporting ground-based experiments of all physical products such as the space robotic arm, robotic arm controller, and hand-eye camera.

[0042] The space robotic arm of the present invention, such as Figure 2 As shown, the spatial robotic arm includes seven joints. Elbow joint 4 is fixed to an elbow fixing connector. The upper part of elbow joint 4 is connected to shoulder joint 3. Shoulder joint 3 is connected to shoulder joint 2 via a shoulder arm. Shoulder joint 2 is connected to shoulder joint 1. The rotation axis of shoulder joint 2 is perpendicular to the rotation axis of shoulder joint 1. The lower part of elbow joint 4 is connected to wrist joint 5. Wrist joint 5 is connected to wrist joint 6 via a wrist arm. Wrist joint 6 is connected to wrist joint 7. Wrist joint 7 is connected to an end effector.

[0043] The joint decoupling air flotation device includes a planar air flotation device and a base. By fixing the elbow joint, the 7-DOF spatial robotic arm is decomposed into "3+1+3" degrees of freedom, which, after decoupling, are respectively a "shoulder joint assembly," an "elbow joint assembly," and a "wrist joint assembly." The "shoulder joint assembly" consists of shoulder joint 3, shoulder arm bar, shoulder joint 2, and shoulder joint 1; the "elbow joint assembly" consists of elbow joint 4; and the "wrist joint assembly" consists of wrist joint 5, wrist arm bar, wrist joint 6, and wrist joint 7. The planar air flotation device has two experimental states:

[0044] The first method involves installing the elbow fixing connector of the space robotic arm on an air-floating base, thereby decoupling the seven-degree-of-freedom space robotic arm into "3+1+3" degrees of freedom. This requires two air-floating devices to support the shoulder arm and wrist arm respectively. After decoupling, the "shoulder joint assembly" includes 3 degrees of freedom, the "elbow joint assembly" includes 1 degree of freedom, and the "wrist joint assembly" includes 3 degrees of freedom, thus achieving complete experimental verification of the seven degrees of freedom of the ground-based robotic arm and its actual rotation in space.

[0045] The second method involves mounting the shoulder joint 1 of the space robotic arm onto an air-floating base via a shoulder fixing connector. This requires three planar air-floating devices to support the shoulder arm, elbow joint 4, and wrist arm, respectively, to achieve complete experimental verification of the rotation of the seven-degree-of-freedom space robotic arm joints 2, 4, 5, 6, and 7 in space.

[0046] The "elbow joint assembly" uses a planar air flotation device to support the shoulder and wrist arms on both sides of the elbow joint, offsetting the bending moment of the joint load and achieving a zero-gravity effect.

[0047] The "shoulder joint assembly" features a fixed elbow structure, a planar air-float device 1 that provides air support for the shoulder arm, and a free shoulder base. Shoulder joint 1 experiences no external load, shoulder joint 2 is loaded by the structure of shoulder joint 1, and shoulder joint 3 is loaded by the assembly of shoulder joints 1 and 2, along with the shoulder arm. A slip ring mechanism is designed on the shoulder arm to balance the load moment of shoulder joint 3, ensuring that shoulder joint 3 and elbow joint 4 bear almost no load torque generated by the weight of shoulder joints 1 and 2.

[0048] The "wrist joint assembly" features a fixed elbow structure, a planar air-float device 2 that provides air support for the wrist arm, and a free overall wrist structure. The load on wrist joint 7 is solely for the end effector, while the load on wrist joint 6 is for both wrist joint 7 and the end effector assembly. A slip ring mechanism is designed on the wrist arm to balance the load moments of wrist joints 6 and 7, as well as the end effector, ensuring that wrist joint 5 and elbow joint 4 bear almost no load torque generated by the weight of wrist joints 6 and 7, and the end effector.

[0049] This invention first utilizes a seven-degree-of-freedom joint decoupling air-float system to provide air-float support for the shoulder, elbow, and wrist joints of a spatial robotic arm. This decouples the seven-degree-of-freedom spatial robotic arm into a "3+1+3" degree of freedom, offsetting its own gravitational bending moment and achieving ±180° ground-based linkage of the seven joints to reproduce spatial motion. Furthermore, it utilizes the proposed... Figure 1 The 7DOF joint space dynamics compensation control method shown calculates the residual torque error of the ground test system in real time, eliminating the ground gravity interference error that is not completely offset by the air-float decoupled test device.

[0050] like Figure 1 As shown, the implementation steps of the space dynamics compensation control method are as follows:

[0051] The first step is to establish an on-orbit dynamic model of the fixed-base space manipulator based on its dynamic parameters, and to calculate the joint torque τ required for the j-th joint by inputting the motion angle, angular velocity, and angular acceleration of each joint. jm j = 1, 2, 3, 4, 5, 6, 7;

[0052] The second step involves installing the elbow fixing connector of the space robotic arm onto the air-floating base, inputting the same motion angles, angular velocities, and angular accelerations for each joint as in the first step, and recording the joint torque sensor measurement value τ of the j-th joint of the space robotic arm in real time. ja ;

[0053] The third step involves selecting the motion angles, angular velocities, and angular acceleration trajectories of each joint of the space robotic arm corresponding to N task segments, and calculating the joint torque τ required for the j-th joint in each task segment according to the first and second steps respectively. jm1 ,τ jm2...τ jmN And record the joint torque sensor measurement value τ of the j-th joint in each task segment. ja1 ,τ ja2 ...τ jaN Where N≥5;

[0054] Fourth step: Calculate the normalized torque compensation value Δτ of the j-th joint using the following formula. js :

[0055] 4.1 Let β = 0;

[0056] 4.2 Order k = [T] i / T s ], t=1;

[0057] 4.3 Proceed to step 4.4;

[0058] 4.4 Determine if t is less than k. If yes, then t = t + 1 and return to step 4.3; otherwise, proceed to step 4.5.

[0059] 4.5 Determine if i is less than N. If so, then If i = i + 1, return to step 4.2; otherwise, proceed to 4.6.

[0060] 4.6 Using the formula Δτ js =β / N to obtain the normalized torque compensation value;

[0061] Among them, T s T is the sampling frequency. i Let τ be the task duration of the i-th task, [] denotes the integer sign, and τ is the duration of the i-th task. jmit and τ jait The calculated joint torque and the joint torque measured by the torque sensor are respectively for the j-th joint of the space robotic arm during the t-th sampling period of the i-th task. jit Let be the joint angle of the j-th joint during the t-th sampling period of the i-th task, in radians;

[0062] The above 4.1-4.6 are equivalent to the normalized torque compensation value.

[0063]

[0064] Fifth, the normalized torque compensation value of the j-th joint is used to perform dynamic compensation on the measured joint torque sensor value of the j-th joint. After compensation, the ground test torque value of the j-th joint is τ. je =τ ja +q j Δτ js , where q jLet be the motion angle of the j-th joint of the current space robotic arm.

[0065] This invention utilizes real-time interaction between a mirror-image robotic arm and a space robotic arm to solve the challenges of ground-based high-stiffness reconstruction, high-speed information interaction between the main body and the mirror image, and high-dynamic control of weak-stiffness space machinery.

[0066] This invention utilizes a seven-degree-of-freedom joint decoupled air-float system and a mirror-image robotic arm to achieve a full-state ground test of space target capture, solving the problems of visual tracking accuracy testing and ground testing, and realizing the full-loop testing of the space robotic arm's space capture software and hardware.

[0067] Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make possible changes and modifications to the technical solutions of the present invention by utilizing the methods and techniques disclosed above without departing from the spirit and scope of the present invention. Therefore, any simple modifications, equivalent changes and alterations made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solutions of the present invention shall fall within the protection scope of the technical solutions of the present invention.

Claims

1. A full-state air-floating ground test system for a space robotic arm, characterized in that: These include joint decoupling air flotation devices, mirror robotic arms, digital twin robotic arms, and six-degree-of-freedom target simulators; Joint decoupling air flotation device: decouples the space robotic arm into a shoulder joint assembly, an elbow joint assembly, and a wrist joint assembly; The decoupled space robotic arm is supported by air buoyancy, which offsets or partially offsets the load torque caused by gravity at the joints of the space robotic arm, thus enabling coordinated movement of each joint of the space robotic arm. Mirror robotic arm: It performs six-dimensional motion in three-dimensional space on the ground according to the drive command of the load motor. Its motion state is consistent with the motion state of each joint of the space robotic arm, realizing the full-loop test of the space robotic arm grasping the target in space; the drive command of the load motor is generated according to the real-time motion state of the joints of the space robotic arm. Six-DOF target simulator: driven by an industrial robotic arm, it simulates the motion characteristics of the captured target relative to the base of the space robotic arm; Digital twin robotic arm: Enables real-time calculation of spatial robotic arm dynamics, 3D display, and calculation of target relative pose; The kinematic parameters and shape parameters related to collision detection of the mirror robotic arm are consistent with those of the space robotic arm. The mirror robotic arm is driven by the joint motion state of the space robotic arm, accurately reproduces the Cartesian motion state of the end effector of the space robotic arm, and directly drives the hand-eye camera to complete the dynamic measurement of the target pose. By utilizing the space dynamics compensation control method, the residual torque error of the ground test system is calculated in real time, eliminating the ground gravity interference error that is not completely offset by the joint decoupling air flotation device.

2. The all-state air-floating ground test system for a space robotic arm according to claim 1, characterized in that: The space robotic arm includes seven joints. Elbow joint 4 is fixed to an elbow fixing connector. The upper part of elbow joint 4 is connected to shoulder joint 3. Shoulder joint 3 is connected to shoulder joint 2 through shoulder arm. Shoulder joint 2 is connected to shoulder joint 1. The rotation axis of shoulder joint 2 is perpendicular to the rotation axis of shoulder joint 1. The lower part of elbow joint 4 is connected to wrist joint 5. Wrist joint 5 is connected to wrist joint 6 through wrist arm. Wrist joint 6 is connected to wrist joint 7. Wrist joint 7 is connected to the end effector. The shoulder joint (3 joints), shoulder arm joint (2 joints), and shoulder joint (1 joint) form the "shoulder joint assembly"; the elbow joint (4 joints) forms the "elbow joint assembly"; and the wrist joint (5 joints), wrist arm joint (6 joints), and wrist joint (7 joints) form the "wrist joint assembly".

3. The all-state air-floating ground test system for a space robotic arm according to claim 2, characterized in that: The joint decoupling air flotation device includes a planar air flotation device and an air flotation base.

4. The all-state air-floating ground test system for a space robotic arm according to claim 3, characterized in that: One test state for a planar air flotation device is as follows: The elbow fixing connector of the space robot arm is installed on the air-floating base, realizing the decoupling of the seven-degree-of-freedom space robot arm into "3+1+3" degrees of freedom. At this time, two air-floating devices are required to support the shoulder arm and the wrist arm respectively. After decoupling, the "shoulder joint assembly" includes 3 degrees of freedom, the "elbow joint assembly" includes 1 degree of freedom, and the "wrist joint assembly" includes 3 degrees of freedom, realizing the complete experimental verification of the seven degrees of freedom of the robot arm on the ground and the actual rotation in space.

5. The all-state air-floating ground test system for a space robotic arm according to claim 3, characterized in that: One test state of the planar air flotation device is as follows: The shoulder joint 1 of the space robot arm is installed on the air flotation base through the shoulder fixing connector. At this time, three planar air flotation devices are required to support the shoulder arm, elbow joint 4, and wrist arm respectively, so as to realize the complete test verification of the rotation of the seven-degree-of-freedom space robot arm joints 2, 4, 5, 6, and 7 in space.

6. The all-state air-floating ground test system for a space robotic arm according to claim 4, characterized in that: Shoulder joint 1 has no external load, shoulder joint 2 is loaded by shoulder joint 1, and shoulder joint 3 is loaded by shoulder joint 1, shoulder joint 2, and shoulder arm. A slip ring mechanism is designed on the shoulder arm to balance the load bending moment of shoulder joint 3 and elbow joint 4, so that shoulder joint 3 and elbow joint 4 hardly bear the load torque generated by the weight of shoulder joint 1 and shoulder joint 2. A slip ring mechanism is designed on the wrist arm to balance the load bending moment of wrist joint 6, wrist joint 7, and end effector, so that wrist joint 5 and elbow joint 4 hardly bear the load torque generated by the weight of wrist joint 6, wrist joint 7, and end effector.

7. A space robotic arm full-state air-floating ground test system according to claim 4 or 5, characterized in that: The load on the 7th wrist joint is solely for the end effector, while the load on the 6th wrist joint is a combination of the 7th wrist joint and the end effector.

8. The all-state air-floating ground test system for a space robotic arm according to claim 1, characterized in that: The spatial dynamics compensation control method is implemented in the following steps: The first step is to establish an on-orbit dynamic model of the fixed-base space manipulator based on its dynamic parameters, and then calculate the joint torque required for the j-th joint by inputting the motion angle, angular velocity, and angular acceleration of each joint. , ; The second step involves installing the elbow fixing connector of the space robotic arm onto the air-floating base, inputting the same motion angles, angular velocities, and angular accelerations for each joint as in the first step, and recording the joint torque sensor measurements of the j-th joint of the space robotic arm in real time. ; The third step involves selecting the motion angles, angular velocities, and angular acceleration trajectories of each joint of the space robotic arm corresponding to N task segments, and calculating the joint torque required for the j-th joint in each task segment according to the first and second steps respectively. And record the joint torque sensor measurement value of the j-th joint in each task segment. Where N≥5; Fourth, use the following formula to calculate the normalized torque compensation value of the j-th joint. : in, Sampling frequency, Let be the task duration of the i-th task segment. , To obtain the sign of the integer, and These are the calculated joint torque of the j-th joint of the space robotic arm during the t-th sampling period of the i-th task, and the joint torque measured by the torque sensor, respectively. Let be the joint motion angle of the j-th joint during the t-th sampling period of the i-th task, in radians; The fifth step involves using the normalized torque compensation value of the j-th joint to perform dynamic compensation on the measured joint torque sensor value of the j-th joint. After compensation, the ground test torque value of the j-th joint is... ,in, Let be the motion angle of the j-th joint of the current space robotic arm.

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