A space manipulator control system based on cartesian impedance control

Abstract

The application relates to the technical field of space mechanical arm control, and discloses a space mechanical arm control system based on Cartesian impedance control, which realizes fine operation control of the space mechanical arm, environment compliant control capture and other functions by real-time solving of contact dynamics of the environment and real-time adjustment of Cartesian impedance control parameters; a mechanical arm body dynamics solving unit realizes functions of mechanical arm arm type angle, DH parameter input and mechanical arm body dynamics solving; a contact dynamics solving unit realizes real-time solving functions of environment stiffness, environment damping and contact collision parameters; and a Cartesian space compliant control calculation unit realizes real-time solving of a position control law with a compliant effect from the output of the previous units. The application also discloses an implementation method of the space mechanical arm system. The application economically and efficiently realizes adaptive flexible capture of a fine operation task of a space robot, is easy to implement, and provides support for effectively guaranteeing and prolonging the service cycle of a spacecraft.

Description

Technical Field

[0001] This invention relates to the field of space robotic arm control technology, and in particular to a space robotic arm control system based on Cartesian impedance control. Background Technology

[0002] With the continuous development of space science and technology, the failure rate and the rate of abandonment caused by changes in demand for on-orbit spacecraft systems (such as satellites, space station modules, solar panels, antennas, etc.) remain high. If the equipment and functions of spacecraft cannot be changed with the changes in demand, the spacecraft system may lose its practical utility long before it reaches the end of its service life.

[0003] Spacecraft are typically designed for a lifespan of over 10 years. However, when a spacecraft malfunctions, requires replacement, or runs out of disposable consumables while in orbit, its operational lifespan could end if timely measures are not taken. Therefore, research into on-orbit servicing robotic arms is urgently needed to address these issues. Summary of the Invention

[0004] The purpose of this invention is to overcome the shortcomings of the prior art and provide a space manipulator control system based on Cartesian impedance control for on-orbit operation scenarios of space manipulators. The system includes: a manipulator kinematics calculation unit, a manipulator body dynamics calculation unit, a contact dynamics calculation unit, and a Cartesian space compliance control calculation unit.

[0005] The robotic arm body dynamics solution unit receives real-time data information sent by the robotic arm kinematics solution unit, processes it, and sends it to the contact dynamics solution unit. At the same time, the robotic arm body dynamics solution unit transmits the solved robotic arm body dynamics parameters and state to the Cartesian space compliant control calculation unit.

[0006] The Cartesian space compliant control calculation unit receives dynamic parameter information from the robotic arm body dynamics calculation unit and the contact dynamics calculation unit, performs inverse dynamics and inverse kinematics calculations with environmental compliance effect in real time, and transmits the position compensation control law to the robotic arm kinematics calculation unit.

[0007] Furthermore, the contact dynamics calculation unit interacts simultaneously with the robotic arm body dynamics calculation unit and the Cartesian space compliance control calculation unit to calculate dynamic parameters with environmental stiffness, environmental damping, and environmental contact collision parameters in real time.

[0008] Furthermore, the robotic arm body dynamics calculation unit receives real-time data information sent by the robotic arm kinematics calculation unit, including: real-time joint space angular acceleration, angular velocity, angular position commands, and real-time torque commands.

[0009] Furthermore, the space robotic arm control system also includes: a debugging host computer and a trajectory planning unit. Based on the task instructions sent by the debugging host computer, and with a predetermined trajectory and preset parameters as input, the trajectory planning unit is driven to output corresponding angular velocity and angular position instructions.

[0010] Furthermore, based on the angular velocity and angular position commands sent by the trajectory planning unit, the robotic arm kinematics calculation unit is driven to output corresponding joint space angular position commands to the robotic arm body dynamics calculation unit.

[0011] The robotic arm body dynamics calculation unit employs a real-time robotic arm dynamics parameter identification method, including:

[0012] The minimum inertial parameter transformation matrix is ​​solved in real time, and the dynamic model of the entire robotic arm is linearized.

[0013] The regression matrix corresponding to the minimum inertia parameter is solved in real time, and the dynamic parameters are identified online when the minimum inertia parameter is known.

[0014] Secondly, the contact dynamics calculation unit employs a real-time self-identification method for environmental parameters, including:

[0015] The nonlinear disturbance observer method is used to estimate the disturbance quantity in the environmental dynamics equation in real time.

[0016] The GJK algorithm is used to perform collision detection calculations for contacting objects, and the environmental parameter solution is performed in real time using an environmental impedance identification method based on Gaussian processes.

[0017] Furthermore, the Cartesian space compliant control calculation unit employs an adaptive Cartesian space compliant control method, including:

[0018] The real-time identification results of the robotic arm dynamic parameters from the robotic arm body dynamics solution unit and the real-time self-identification results of the environmental parameters from the contact dynamics solution unit are received as inputs to the Cartesian space compliant control calculation unit.

[0019] Transform the Cartesian space environment dynamics equations into joint space dynamics equations;

[0020] The control law is superimposed on the joint space dynamic equations and calculated using standard inverse dynamics, and an adaptive law is designed to adjust the parameters of the control law in real time.

[0021] The control law is calculated in real time with admittance, and the result is sent to the kinematics calculation unit of the robotic arm as input.

[0022] Compared with the prior art, the beneficial effects of the present invention are:

[0023] (1) The contact dynamics calculation unit effectively realizes the real-time detection and identification of environmental stiffness, environmental damping and contact collision parameters of the space robot arm during various on-orbit precision control tasks;

[0024] (2) Different compliant control compensations are made by using Cartesian space compliant control calculation units, etc. This control strategy does not affect the existing kinematic control strategy of the space robot arm. It is economical, easy to implement, and can be widely used in various space robot arm compliant control on-orbit fine manipulation tasks.

[0025] (3) Through the trajectory planning unit, the robotic arm kinematics calculation unit, and the robotic arm body dynamics calculation unit, it serves as an auxiliary platform for astronauts to achieve precise control inside and outside the cabin, completes the precise operation function of the on-orbit service robot, and provides a foundation for effectively guaranteeing and extending the service life of the spacecraft. Attached Figure Description

[0026] The accompanying drawings are provided to further illustrate the invention and form part of the specification. They are used in conjunction with embodiments of the invention to explain the invention and do not constitute a limitation thereof. In the drawings:

[0027] Figure 1 This is a block diagram of a space robotic arm control system according to the present invention;

[0028] Figure 2 This is a flowchart illustrating the operation of a space robotic arm control system according to the present invention. Detailed Implementation

[0029] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0030] Those skilled in the art will understand that, unless specifically stated otherwise, the singular forms “a,” “an,” “the,” and “the” used herein may also include the plural forms. It should be further understood that the term “comprising” as used in this specification means the presence of the stated features, integers, steps, operations, elements, and / or components, but does not exclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and / or groups thereof.

[0031] The present invention will now be described in further detail with reference to the accompanying drawings.

[0032] Example 1

[0033] To enable more precise and compliant on-orbit servicing and manipulation tasks of space robotic arms, this invention proposes a space robotic arm control system based on Cartesian impedance control. This control platform can achieve precise extravehicular manipulation of the space robotic arm. Figure 1 As shown, the space robotic arm control system of the present invention consists of the following components: a debugging host computer, upper-level nodes, a trajectory planning unit, a robotic arm kinematics calculation unit, a robotic arm body dynamics calculation unit, a contact dynamics calculation unit, and a Cartesian space compliant control calculation unit.

[0034] Specifically, in this embodiment, the space manipulator control system based on Cartesian impedance control includes: a manipulator kinematics calculation unit, a manipulator body dynamics calculation unit, a contact dynamics calculation unit, and a Cartesian space compliance control calculation unit;

[0035] The robotic arm body dynamics solution unit receives real-time data information sent by the robotic arm kinematics solution unit, processes it, and sends it to the contact dynamics solution unit. At the same time, the robotic arm body dynamics solution unit transmits the solved robotic arm body dynamics parameters and state to the Cartesian space compliant control calculation unit.

[0036] The Cartesian space compliant control calculation unit receives dynamic parameter information from the robotic arm body dynamics calculation unit and the contact dynamics calculation unit, performs inverse dynamics and inverse kinematics calculations with environmental compliance effect in real time, and transmits the position compensation control law to the robotic arm kinematics calculation unit.

[0037] The contact dynamics calculation unit interacts with both the robotic arm body dynamics calculation unit and the Cartesian space compliance control calculation unit to calculate dynamic parameters with environmental stiffness, environmental damping, and environmental contact collision parameters in real time.

[0038] Specifically, in this embodiment, the real-time data information received by the robotic arm body dynamics calculation unit from the robotic arm kinematics calculation unit includes: real-time joint space angular acceleration, angular velocity, angular position commands, and real-time torque commands.

[0039] In addition, the space robotic arm control system also includes a debugging host computer and a trajectory planning unit. Based on the task instructions sent by the debugging host computer, and with a predetermined trajectory and preset parameters as input, the trajectory planning unit is driven to output corresponding angular velocity and angular position instructions.

[0040] Furthermore, based on the angular velocity and angular position commands sent by the trajectory planning unit, the robotic arm kinematics calculation unit is driven to output corresponding joint space angular position commands to the robotic arm body dynamics calculation unit.

[0041] The robotic arm body dynamics calculation unit employs a real-time robotic arm dynamics parameter identification method, including:

[0042] The minimum inertial parameter transformation matrix is ​​solved in real time, and the dynamic model of the entire robotic arm is linearized.

[0043] The regression matrix corresponding to the minimum inertia parameter is solved in real time, and the dynamic parameters are identified online when the minimum inertia parameter is known.

[0044] Secondly, the contact dynamics calculation unit employs a real-time self-identification method for environmental parameters, including:

[0045] The nonlinear disturbance observer method is used to estimate the disturbance quantity in the environmental dynamics equation in real time.

[0046] The GJK algorithm is used to perform collision detection calculations for contacting objects, and the environmental parameter solution is performed in real time using an environmental impedance identification method based on Gaussian processes.

[0047] Furthermore, the Cartesian space compliant control calculation unit employs an adaptive Cartesian space compliant control method, including:

[0048] The real-time identification results of the robotic arm dynamic parameters from the robotic arm body dynamics solution unit and the real-time self-identification results of the environmental parameters from the contact dynamics solution unit are received as inputs to the Cartesian space compliant control calculation unit.

[0049] Transform the Cartesian space environment dynamics equations into joint space dynamics equations;

[0050] The control law is superimposed on the joint space dynamic equations and calculated using standard inverse dynamics, and an adaptive law is designed to adjust the parameters of the control law in real time.

[0051] The control law is calculated in real time with admittance, and the result is sent to the kinematics calculation unit of the robotic arm as input.

[0052] Example 2:

[0053] like Figure 2 As shown, implementing the space robotic arm control system based on Cartesian impedance control in this embodiment includes the following steps:

[0054] Step 1: The astronaut issues instructions to the debugging host computer or upper-level node, which then issues instructions to the trajectory planning unit.

[0055] Step 2: Generate ideal trajectory planning instructions from the trajectory planning unit, including angular velocity instructions and angular position instructions;

[0056] Step 3: The robotic arm kinematics calculation unit receives the angular position command from the trajectory planning unit, performs inverse kinematics solution, and then sends it to the robotic arm body dynamics calculation unit.

[0057] Step 4: The minimum inertial parameter transformation matrix is ​​solved in real time by the robotic arm body dynamics solution unit;

[0058] Step 5: Linearize the dynamic model of the entire robotic arm;

[0059] Step 6: Solve the regression matrix corresponding to the minimum inertia parameter in real time;

[0060] Step 7: Perform online identification of dynamic parameters when the minimum inertial parameter is known;

[0061] Step 8: Use the nonlinear disturbance observer method to estimate the disturbance quantity in the environmental dynamics equation in real time;

[0062] Step 9: Use the GJK algorithm to perform collision detection calculations for contacting objects;

[0063] Step 10: Real-time environmental parameter calculation is performed using the environmental impedance identification method based on Gaussian processes;

[0064] Step 11: Receive the calculation results from the robotic arm body dynamics solution unit and the contact dynamics solution unit, use them as input to the Cartesian space compliant control calculation unit, and merge them into the overall Cartesian space dynamic parameters;

[0065] Step 12: Convert the Cartesian space environment dynamics equations into joint space dynamics equations;

[0066] Step 13: Superimpose the results of Step 12 into the control law calculated using standard inverse dynamics;

[0067] Step 14: Design an adaptive law to adjust the parameters of the control law in step 13 in real time;

[0068] Step 15: Calculate the admittance control law in real time based on the results of Steps 13 and 14;

[0069] Step 16: Superimpose the results of Step 15 onto the kinematics calculation unit of the robotic arm as part of its input;

[0070] Step 17: Astronauts confirm whether the system can operate normally and whether the control performance meets mission requirements;

[0071] Step 18: If the requirements are met, proceed to step 20; if the requirements are not met, proceed to step 19.

[0072] Step 19: Stop the robotic arm abruptly and determine if trajectory planning needs to be re-executed; if so, proceed to step 2; if not, proceed to step 3.

[0073] Step 20: Output, display, and save the animation and video of the trajectory and control, and transmit telemetry data to the ground and upper-level nodes.

[0074] This embodiment achieves precise operation control and environmental compliant control capture of the space robotic arm by real-time calculation of its body dynamics and identification of environmental dynamic parameters. The robotic arm body dynamics calculation unit implements functions such as inputting the robotic arm's arm angle and DH parameter, and calculating the robotic arm's body dynamics. The contact dynamics calculation unit implements real-time calculation of environmental stiffness, environmental damping, and contact collision parameters. The Cartesian space compliant control calculation unit calculates a position control law with compliant effect in real-time based on the outputs of the previous units. This invention also discloses a method for implementing this space robotic arm system.

[0075] It can be used for on-orbit servicing and maintenance tasks of space robotic arms, and economically and efficiently realizes the precision and compliance of space robotic arm control tasks. It has the beneficial effects of being economical and highly practical, and can be widely applied to the precision control and on-orbit maintenance tasks of other space robots.

[0076] Finally, it should be noted that the above descriptions are merely preferred embodiments of the present invention, and the scope of protection of the present invention is not limited to the above embodiments. All technical solutions falling within the scope of the present invention's concept are within the scope of protection of the present invention. It should be pointed out that for those skilled in the art, any improvements and modifications made without departing from the principles of the present invention should also be considered within the scope of protection of the present invention. The technical features of the above embodiments can be combined arbitrarily. For the sake of brevity, not all possible combinations of the technical features in the above embodiments have been described. However, as long as the combination of these technical features does not contradict each other, it should be considered within the scope of this specification.

Claims

1. A space robotic arm control system based on Cartesian impedance control, characterized in that, include: The robotic arm kinematics calculation unit, the robotic arm body dynamics calculation unit, the contact dynamics calculation unit, and the Cartesian space compliant control calculation unit; The robotic arm body dynamics calculation unit receives real-time data information sent by the robotic arm kinematics calculation unit, processes it, and sends it to the contact dynamics calculation unit. At the same time, the robotic arm body dynamics calculation unit transmits the calculated parameters and states of the robotic arm body dynamics to the Cartesian space compliant control calculation unit. The Cartesian space compliant control calculation unit receives dynamic parameter information from the robotic arm body dynamics calculation unit and the contact dynamics calculation unit, performs inverse dynamics and inverse kinematics calculations with environmental compliance effect in real time, and transmits the position compensation control law to the robotic arm kinematics calculation unit. The contact dynamics calculation unit interacts with both the robotic arm body dynamics calculation unit and the Cartesian space compliance control calculation unit to calculate dynamic parameters with environmental stiffness, environmental damping, and environmental contact collision parameters in real time. The robotic arm body dynamics calculation unit receives real-time data information sent by the robotic arm kinematics calculation unit, including: real-time joint space angular acceleration, angular velocity, angular position commands, and real-time torque commands; The robotic arm body dynamics calculation unit employs a real-time robotic arm dynamics parameter identification method, including: The minimum inertial parameter transformation matrix is ​​solved in real time, and the dynamic model of the entire robotic arm is linearized. The regression matrix corresponding to the minimum inertia parameter is solved in real time, and the dynamic parameters are identified online when the minimum inertia parameter is known. The contact dynamics calculation unit employs a real-time self-identification method for environmental parameters, including: The nonlinear disturbance observer method is used to estimate the disturbance quantity in the environmental dynamics equation in real time. The GJK algorithm is used to perform collision detection calculations on contacting objects, and the environmental parameter solution is performed in real time using an environmental impedance identification method based on Gaussian processes. The Cartesian space compliant control calculation unit employs an adaptive Cartesian space compliant control method, including: The real-time identification results of the robotic arm dynamic parameters from the robotic arm body dynamics solution unit and the real-time self-identification results of the environmental parameters from the contact dynamics solution unit are received as inputs to the Cartesian space compliant control calculation unit. Transform the Cartesian space environment dynamics equations into joint space dynamics equations; The control law is superimposed on the joint space dynamic equations and calculated using standard inverse dynamics, and an adaptive law is designed to adjust the parameters of the control law in real time. The control law is calculated in real time with admittance, and the result is sent to the kinematics calculation unit of the robotic arm as input.

2. The space robotic arm control system based on Cartesian impedance control according to claim 1, characterized in that, The space robotic arm control system also includes: a debugging host computer and a trajectory planning unit. Based on the task instructions sent by the debugging host computer, and with a predetermined trajectory and preset parameters as input, the trajectory planning unit is driven to output corresponding angular velocity and angular position instructions.

3. The space robotic arm control system based on Cartesian impedance control according to claim 2, characterized in that, The trajectory planning unit sends angular velocity and angular position commands to drive the robotic arm kinematics calculation unit to output corresponding joint space angular position commands to the robotic arm body dynamics calculation unit.

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