Sliding mode control method for floating base space robots fusing decoupled dynamics models

Abstract

This invention provides a sliding mode control method for a floating-based space robot that integrates a decoupled dynamics model, belonging to the field of controller design technology. This invention establishes contact determination indices and floating-based stability indices for the floating-based space robot; constructs a logical switching index and a globally unified control law; determines the operating mode of the floating-based space robot based on the logical switching index; and controls the floating-based space robot based on the globally unified control law. The globally unified control law of this invention includes a full-dimensional sliding mode control law and a reduced-dimensional sliding mode control law, which can minimize control abrupt changes and system oscillations that may occur during switching, improving the adaptability and task execution continuity of the space robot in multi-task scenarios. Through the collaborative design of full-dimensional and reduced-dimensional controllers, smooth switching between different control modes is achieved, ensuring the global stability of the system in different control modes and during their switching processes.

Description

Technical Field

[0001] This invention belongs to the field of controller design technology, specifically a sliding mode control method for a floating-based space robot that integrates a decoupled dynamic model. Background Technology

[0002] Floating-based space robot systems employ two control modes during space missions: free floating and free flight. Existing controller design methods based on dynamic models largely rely on model feedforward compensation, which is sensitive to the accuracy of dynamic parameters and lacks robustness. Taking advantage of the system-level decoupling and physical passivity of the fused decoupled dynamic model, full-dimensional and reduced-dimensional controllers can be designed to achieve sliding mode control for both control modes. Furthermore, by analyzing the contact and stability indices of the floating-based robot system, logical criteria for control mode switching are constructed, enabling smooth switching between different control modes and improving the system's stability and control performance in complex mission environments. Summary of the Invention

[0003] To address the shortcomings of existing technologies, this invention provides a sliding mode control method for a floating-based space robot that integrates a decoupled dynamics model, comprising the following steps:

[0004] Acquire measurement signals from the end effector of the floating-based space robot, and establish contact determination index and floating-based stability index for the floating-based space robot;

[0005] Based on the contact determination index and the floating base stability index, a logical switching index is constructed.

[0006] A globally unified control law is constructed to determine the working mode of the floating-based space robot based on the logic switching index, and the floating-based space robot is controlled based on the globally unified control law.

[0007] Furthermore, the specific method for establishing the contact determination index and floating base stability index of the floating base space robot is as follows:

[0008] The measurement signals from the end effector of the floating-based space robot include the forces and torques acting on its end effector. Based on the measurement signals acquired by the six-dimensional force / torque sensor, a dimensionless normalized contact determination index for the floating-based space robot is established. and floating base stability index As shown in the formula below:

[0009] ;

[0010] in, , These are the contact thresholds for force and torque, respectively. , These are the integral thresholds for the floating base attitude angle change error and the floating base attitude angle change error, respectively. For the force observation values ​​of the end effector of the floating-based space robot, For the observed torque values ​​of the end effector of the floating-based space robot, The first three values ​​of the error of the six-dimensional force / torque sensor represent the difference between the floating base attitude angular velocity and the expected value.

[0011] Based on contact determination index and floating base stability index Build logical switching metrics As shown in the formula below:

[0012] .

[0013] Furthermore, the floating space robot's operating modes include free flight mode and free float mode.

[0014] Furthermore, the working mode of the floating-based space robot is set based on logical switching indicators. The specific method is as follows:

[0015] When the logic switching index is not zero, the working mode of the floating base space robot is set to free flight mode.

[0016] When the logic switching index is zero, the working mode of the floating base space robot is set to free floating mode.

[0017] Furthermore, the globally unified control law includes the full-dimensional sliding mode control law and the reduced-dimensional sliding mode control law. As shown in the formula below:

[0018] ;

[0019] in, For full-dimensional sliding mode control law, This is a sliding mode control law for dimension reduction.

[0020] Furthermore, the specific method for controlling the floating space robot based on a globally unified control law is as follows:

[0021] When the floating-based space robot is in free flight mode, it is controlled through a full-dimensional control mode.

[0022] When the floating-based space robot operates in free-floating mode, it is controlled through a dimensionality reduction control mode.

[0023] Furthermore, the full-dimensional control mode includes:

[0024] Design a fully robust sliding mode control law As shown in the formula below:

[0025] ;

[0026] Among them, positive definite matrix For linear feedback gain, For the sliding surface of the full-dimensional sliding mode controller, To predict the external force mapping term, For sliding mode gain, It is a positive definite smoothing factor matrix. For the differential of the full-dimensional state tracking error, It is a positive definite diagonal gain matrix. To lock space velocity, For the desired generalized velocity, the positive definite matrix Here is the static robust gain matrix used to cover the static uncertainties of the system; positive definite matrix. The linear dynamic compensation gain matrix is ​​a positive definite matrix. The nonlinear dynamic compensation gain matrix is ​​a positive definite matrix. The gain matrix for force measurement uncertainty;

[0027] Predicting external force mapping terms For measurement signal The mapping of the first-order linear extrapolated predicted value is shown in the following formula:

[0028] ;

[0029] in, The predicted value is from a six-dimensional force / torque sensor. For predicting gain; The equivalent number of sampling steps corresponding to the time delay. For sensor time delay, The sampling period for the control system; For sensor force / torque increments; This is the velocity mapping matrix. This is the global mapping matrix. This is the end effector-to-robotic arm joint transformation matrix;

[0030] Through the full-dimensional robust sliding mode control law By controlling the floating-based space robot, the control force rotation of the floating base and the joint control torque of the space robot in free flight mode are obtained.

[0031] Furthermore, the dimensionality reduction control mode includes:

[0032] Set the base control force spinor to a zero vector;

[0033] Fully robust sliding mode control law Integral gain matrix Linear feedback gain matrix Linear dynamic compensation gain matrix Nonlinear dynamic compensation gain matrix Force measurement uncertainty gain matrix It is divided into a main sub-block corresponding to the base momentum control channel and a main sub-block corresponding to the robotic arm joint control channel;

[0034] A dimension-reduced robust sliding mode control law is constructed based on the master block corresponding to the base momentum control channel. As shown in the formula below:

[0035] ;

[0036] in, For the sliding surface of the dimension reduction sliding mode controller, To differentiate the state tracking error in a reduced dimension, The dimension-reduced positive definite diagonal gain matrix. To reduce the linear feedback gain of the sliding mode controller, To reduce sliding mode gain, The dimension-reduced positive definite smoothing factor matrix, For the dimension-reduced static robust gain matrix, For dimension reduction, linear dynamic compensation gain matrix, This is the gain matrix for dimensionality reduction and nonlinear dynamic compensation.

[0037] The beneficial effects of adopting the above technical solution are as follows: This invention provides a sliding mode control method for a floating-based space robot based on a fused and decoupled dynamic model. It constructs a switchable, globally unified control law and establishes control mode switching logic criteria based on contact determination indices and floating-based stability indices. This minimizes potential control abrupt changes and system oscillations during switching, improving the space robot's adaptability and task execution continuity in multi-task scenarios. This invention designs a sliding mode controller based on a physically passive fused and decoupled dynamic model. The controller incorporates gains covering static, dynamic, and force measurement uncertainties, effectively improving system robustness. Through the collaborative design of full-dimensional and reduced-dimensional controllers, smooth switching between different control modes is achieved, ensuring the global stability of the system in different control modes and during their switching processes. Attached Figure Description

[0038] Figure 1 Flowchart of the sliding mode control method for a floating base space robot based on a fused and decoupled dynamic model provided in Embodiment 1 of this invention;

[0039] Figure 2The sliding mode controller based on a fused decoupled dynamics model provided in Embodiment 1 of this invention;

[0040] Figure 3 A schematic diagram of the space robot's approach, contact interaction, and pose recovery task provided in Embodiment 1 of the present invention;

[0041] Figure 4 The sliding membrane controllers established by different methods provided in Embodiment 1 of the present invention include (a) an output feedforward PD controller based on a recursive dynamics algorithm, (b) a force feedforward PD controller based on a global closed matrix model, and (c) a sliding membrane controller based on the Euler-Lagrange equation.

[0042] Figure 5 Speed ​​error analysis of different controller joints 1 provided in Embodiment 1 of the present invention;

[0043] Figure 6 Speed ​​error analysis of joint 6 in different controllers provided in Embodiment 1 of the present invention;

[0044] Figure 7 The comparison results of base attitude deflection under different controllers provided in Embodiment 1 of the present invention are as follows: (a) is the base attitude deflection result of the output feedforward PD controller based on the recursive dynamics algorithm of controller 1; (b) is the base attitude deflection result of the force feedforward PD controller based on the global closed matrix model of controller 2; (c) is the base attitude deflection result of the sliding membrane controller based on the Euler-Lagrange equation of controller 3; and (d) is the base attitude deflection result of the sliding membrane controller based on the fusion decoupled dynamics of controller 4. Detailed Implementation

[0045] The specific implementation methods of this application will be further described in detail below with reference to the accompanying drawings and embodiments.

[0046] Example 1:

[0047] A sliding mode control method for a floating-based space robot that integrates decoupled dynamic models, such as Figure 1 As shown, it includes the following steps:

[0048] Step 1: Obtain the observed values ​​of the forces and torques acting on the end effector of the floating-based space robot, and establish the contact determination index and floating-based stability index for the floating-based space robot.

[0049] Based on measurements from a six-dimensional force / torque sensor Establish a dimensionless normalized contact determination index for floating-based space robots. With floating base stability index As shown in the formula below:

[0050] ;

[0051] In the formula, , These are the contact thresholds for force and torque, respectively. , These are the integral thresholds for the floating base attitude angle change error and the floating base attitude angle change error, respectively. For force observations, For torque observations, The first three values ​​of the error of the six-dimensional force / torque sensor represent the difference between the floating base attitude angular velocity and the expected value.

[0052] The contact judgment index and the floating base stability index clarify the state switching mechanism of the floating base space robot system. Specifically, when the space robot's attitude angle and its changes are within a set threshold range and the force and torque applied to its end effector do not trigger the corresponding threshold, the floating base space robot is determined to be in free-floating control mode; when any force or torque amplitude exceeds the corresponding threshold, the system enters a state switching mode. and When contact is detected, the system must switch to full-dimensional mode to perform contact operations. This applies when the floating base's attitude angle or changes exceed the corresponding threshold. and When the floating base space robot is determined to be in an unstable state, it is necessary to switch to the full-dimensional control mode to carry out stabilization control work.

[0053] Step 2: Construct a logical switching index based on the contact determination index and the floating base stability index;

[0054] Logical switching indicators are used to enable space robots to autonomously and explicitly switch between dimensionality-reduced control modes and full-dimensional control modes, such as... Figure 2 As shown, in this example, based on the contact determination index and floating base stability index Build logical switching metrics As shown in the formula below:

[0055] ;

[0056] Step 3: Construct a global unified control law, determine the working mode of the floating base space robot based on the logic switching index, and control the floating base space robot based on the global unified control law;

[0057] Global unified control laws include full-dimensional sliding mode control laws and reduced-dimensional sliding mode control laws. As shown in the formula below:

[0058] ;

[0059] in, For full-dimensional sliding mode control law, For dimension reduction sliding mode control law;

[0060] The working mode of the floating base space robot is determined based on the logical switching index, including free flight mode and free float mode;

[0061] When logical switching indicators When the floating space robot is in free flight mode, the working mode is set to free flight mode. When the logic switching index determines that the system is in free flight mode, the external forces acting on the system are predicted based on the system observations, and the system is controlled by a full-dimensional robust sliding mode control law based on the fused decoupled dynamics model.

[0062] When logical switching indicators When the floating base space robot is in free floating mode, the working mode of the floating base space robot is set to free floating mode. When the logic switching index determination system is in free floating mode, the control force spinor of the floating base space robot is set to zero vector, and the system is controlled by a dimension-reduced robust sliding mode control law based on the fusion decoupled dynamics model.

[0063] Therefore, this embodiment is based on logical switching indicators. During the approach phase, underactuated constraints are applied to the floating base of the space robot, and the dimensionality reduction control law is used only by expanding the zero vector to match the generalized input dimension. Drive joint movement. During the contact operation phase, activate the full-dimensional control mode. This releases control of the space robot's floating base and introduces external force compensation to suppress contact momentum impact.

[0064] The full-dimensional robust sliding mode control law based on the fused decoupled dynamics model includes:

[0065] Considering that the high-frequency switching of the sign function in sliding mode control can easily cause severe chattering between the robot arm joints and the base, this embodiment uses a hyperbolic tangent function. Instead of traditional symbolic functions, a fully robust sliding mode control law is designed by combining the physical passive structural characteristics of the fusion decoupled dynamics model of floating-based space robots. As shown in the formula below:

[0066] ;

[0067] Among them, positive definite matrix The linear feedback gain is used to provide a damping injection similar to PD control to improve closed-loop transients and suppress velocity-dependent disturbances; It is an integral sliding surface introduced to eliminate steady-state errors; To predict the external force mapping term; To achieve sliding mode gain, an online scheduling strategy is adopted to balance the robustness and conservatism of the control system. This is a positive definite smoothing factor matrix used to adjust the hyperbolic tangent function. The steepness of the slope is adjusted to form a boundary layer near the sliding surface to smoothly control the output; It is a positive definite diagonal gain matrix; To lock space velocity, For the desired generalized velocity; positive definite matrix Here is the static robust gain matrix used to cover the static uncertainties of the system; positive definite matrix. The linear dynamic compensation gain matrix is ​​a positive definite matrix. The nonlinear dynamic compensation gain matrix is ​​a positive definite matrix. The gain matrix for force measurement uncertainty;

[0068] Linear dynamic compensation gain matrix and nonlinear dynamic compensation gain matrix Compensation is performed on the dynamic errors of the first-order and second-order models related to velocity, respectively, and the force measurement uncertainty gain matrix is ​​calculated. By leveraging the relative measurement accuracy of a six-dimensional force / torque sensor, the maximum component of the external force error after dynamic mapping is used as the overall error scale, thereby achieving real-time coverage of the uncertainty in external contact force measurement.

[0069] Because actual sensor signals are inevitably affected by sampling delay, quantization error, and phase lag, directly using measured values ​​will weaken the control law's response speed to changes in contact force, and may even induce high-frequency chattering in the sliding mode term. Therefore, a fully robust sliding mode control law is necessary. In the middle, predict the external force mapping term For measurement signal The mapping of the first-order linear extrapolated predicted value is shown in the following formula:

[0070] ;

[0071] in, The predicted value is from a six-dimensional force / torque sensor. To predict gain, a trade-off is made between delay compensation capability and noise amplification; The equivalent number of sampling steps corresponding to the time delay. For sensor time delay, The sampling period for the control system; For sensor force / torque increments; This is the velocity mapping matrix. This is the global mapping matrix. This is the end effector-to-robotic arm joint transformation matrix;

[0072] The first-order linear extrapolation prediction method described above can effectively compensate for the phase lag caused by sensor delay and filtering, and effectively improve the robust stability and control smoothness of the system.

[0073] Based on the physical passivity of the fused decoupled dynamics model, it is known that as long as the sliding mode gain matrix... For any robotic arm Design parameters The following component form conditions must be met, i.e. Then there exist positive constants. This makes the Lyapunov function ,in As the upper limit of the disturbance, according to the theory of uniform eventual bounded stability, the sliding surface of the above-mentioned full-dimensional sliding mode controller is... It will eventually converge to a point centered at the origin with a radius of... Within a compact set that is proportional to each other, and when When the boundary layer is reduced to zero, the system control behavior approaches the ideal sliding mode state.

[0074] The dimensionless robust sliding mode control law based on the fusion decoupled dynamics model includes:

[0075] Dimensionality-reduced robust sliding mode control law In fully robust sliding mode control law In the design, the integral gain matrix Linear feedback gain matrix and sliding mode gain related parameter matrix It is designed based on a constant positive definite diagonal matrix. This embodiment considers the space velocity of the locked configuration. Physically, it is naturally divided into the base momentum space. Joint space of robotic arm Each of the above full-dimensional parameter matrices can be uniquely decomposed into the following block diagonal form:

[0076] ;

[0077] Among them, subscript This indicates the corresponding momentum control channel of the base. Main child block, subscript This indicates the corresponding joint control channel of the robotic arm. Main block.

[0078] Momentum conservation in free-floating control mode Physical constraints, full-dimensional sliding surface The evolution depends only on the joint space state. Therefore, the corresponding joint control channels of the robotic arm can be directly extracted from the above full-dimensional parameter matrix. Master block Combining the dimension reduction state tracking error and its derivative Design of joint space sliding surface and robust sliding mode control law As shown in the formula below:

[0079] ;

[0080] in, For the sliding surface of the dimension reduction sliding mode controller, To differentiate the state tracking error in a reduced dimension, The dimension-reduced positive definite diagonal gain matrix. To reduce the linear feedback gain of the sliding mode controller, To reduce sliding mode gain, The dimension-reduced positive definite smoothing factor matrix, For the dimension-reduced static robust gain matrix, For dimension reduction, linear dynamic compensation gain matrix, For dimension reduction, nonlinear dynamic compensation gain matrix;

[0081] The above design demonstrates that the gain parameters of the dimensionality-reduced controller strictly correspond, both numerically and structurally, to the joint space components of the full-dimensional parameters. This construction method, based on direct matrix decomposition, not only inherits the positive definiteness of the original parameters but also ensures the consistency of the physical action mechanism of the control system during dimensionality transformation, achieving a smooth transition from full-dimensional control to dimensionality-reduced control. Similar to the full-dimensional controller, the aforementioned dimensionality-reduced sliding mode variables will eventually converge to a point centered at the origin with a radius equal to... Within the proportionally compact set, the above derivation rigorously proves that the stability parameter design of the full-dimensional controller constitutes the envelope of the stability requirements of the dimensionality-reduced subsystem.

[0082] Step 4: Control the floating space robot based on a globally unified control law;

[0083] By integrating the control force spindle of the floating base of the space robot with the joint control torque as the system control output, stable control of the floating base space robot can be achieved under different control modes.

[0084] The stable control of the floating space robot under different control modes specifically refers to the global stability of sliding mode control.

[0085] Step 3 discusses the fully robust sliding mode control law. and robust sliding mode control law The stability of the mode switching mechanism is crucial. Therefore, the key to proving this lies in the critical moment of mode switching. The physical continuity of the control torque. It should be noted that at the critical moment of control mode switching... Because the threshold is set small enough, the system state at the moment of switching satisfies the condition of minimal external force. Satellite base correlation components in full-dimensional sliding mode surface Using the control parameters of the dimension-reduced robust sliding mode control law discussed in step 3, corresponding to the lower right block result of the full-dimensional controller, the full-dimensional control law naturally degenerates at the mode switching moment, as shown in the following formula:

[0086] ;

[0087] The above derivation shows that at the instant of control mode switching, the numerical connection between the control quantity calculated by the full-dimensional controller and the output of the reduced-dimensional controller is approximately smooth, thus avoiding drastic control quantity fluctuations caused by the switching. In summary, the system satisfies Lyapunov stability in each sub-stage, and the control output remains continuous during the switching process, thereby ensuring the global robust stability of the space robot throughout its on-orbit servicing process.

[0088] like Figure 3 As shown, in this embodiment of the invention, to comprehensively verify the adaptability and robustness of the proposed sliding mode controller based on the fusion and decoupled dynamic structural characteristics in space missions, simulation experiments were conducted focusing on the space robot's approach, contact interaction, and pose recovery processes. The total simulation time was set to [duration to be filled in]. The first 15 seconds are the approach phase, 15-25 seconds are the contact and interaction phase, and 25-50 seconds are the posture recovery phase.

[0089] like Figure 4 As shown in this embodiment, to demonstrate the performance advantages of the proposed sliding mode controller based on the fusion decoupling model, corresponding controllers are designed for the recursive Newton-Euler dynamics algorithm, the globally closed matrix form dynamics model, and the Euler-Lagrange equations, respectively. (a) is the output feedforward PD controller based on the recursive dynamics algorithm, (b) is the force feedforward PD controller based on the globally closed matrix model, and (c) is the sliding mode controller based on the Euler-Lagrange equations. The recursive Newton-Euler dynamics algorithm and the globally closed matrix form dynamics model, lacking physical passivity, use a PD control architecture as a comparison controller, which is simplified to Control 1 and Control 2. Since the Euler-Lagrange equations do not have the ability to explicitly decouple external forces, the external force feedforward compensation term is removed in the control law design, and a robust control strategy that treats contact external forces as system disturbances is constructed, which is simplified to Control 3.

[0090] like Figure 5As shown, in this embodiment, during the approach phase, the focus is on examining the trajectory tracking capabilities of each controller under conditions of initial position deviation. Considering the order of different joints in the system dynamics calculation, the root joint 1, which is highly sensitive to model accuracy, is selected as a representative to evaluate the controller performance of the space robot under the premise of initial position error of the robotic arm joint angle. At the end of this phase, the joint residual velocity error corresponding to the sliding mode controller (controller 4) based on the fusion decoupling model proposed in this invention is relatively small, indicating that the proposed sliding mode controller can reduce the impact caused by initial state deviation to a certain extent. This characteristic is closely related to the physical passive structural characteristics of the fusion decoupling dynamics model.

[0091] like Figure 6 As shown, in this embodiment, during the contact interaction phase, the main analysis focuses on the system's control performance under continuous external force and the model's ability to represent external forces. Combined with... Figure 6 Further analysis revealed that the weighted values ​​of the joint speed errors were obtained as shown in Table 1. It was found that controller 4 exhibited a smaller weighted value of joint speed errors during this stage, reflecting its advantage in control consumption.

[0092] Table 1 Weighted values ​​of joint velocity errors during the contact interaction phase

[0093]

[0094] Meanwhile, the comparison of the base posture response to external force disturbances in Table 2 further illustrates that the introduction of explicit analytical methods for external forces in the control process helps improve the system response characteristics. These results are related to the system-level decoupling characteristics of the fused decoupled dynamics model, namely, the model simultaneously satisfies the diagonalization of the inertia matrix, the global decomposition of the Coriolis force and centrifugal force terms, and the explicit mapping conditions of external forces. This characteristic is another important structural advantage of this model besides its physical passivity.

[0095] Table 2. Analysis results of the base attitude stability performance under different controllers.

[0096]

[0097] like Figure 7As shown, in this embodiment, the pose recovery phase is a continuation process after contact interaction. Its goal is to reduce the attitude disturbance introduced by contact, so that the system can gradually recover to a stable state and meet the conditions for transitioning from free flight control mode to free float control mode. Among them, (a) is the base attitude deflection result of the output feedforward PD controller based on the recursive dynamics algorithm of controller 1, (b) is the base attitude deflection result of the force feedforward PD controller based on the global closed matrix model of controller 2, (c) is the base attitude deflection result of the sliding membrane controller based on the Euler-Lagrange equation of controller 3, and (d) is the base attitude deflection result of the sliding membrane controller based on the fusion decoupled dynamics of controller 4. Figure 7 As shown, the pose deflection of controller 4 is relatively smaller during this stage. The results in Table 3 further reflect that the system possesses a certain degree of dimensionality reduction control capability after the disturbance stabilizes. These performance characteristics can be considered as the result of the synergistic effect of physical passivity and system-level decoupling characteristics in the fused decoupled dynamics model.

[0098] Table 3 Comparison of dimensionality reduction results under different controllers

[0099]

[0100] Example 2:

[0101] This embodiment proposes an electronic device, including: one or more processors, and a memory, wherein the memory is used to store instructions, and when the instructions are executed by the one or more processors, the one or more processors execute the sliding mode control method for a floating-based space robot based on a fused decoupled dynamic model.

[0102] The electronic device may be a mobile phone, computer, or tablet computer, etc., and includes a memory and a processor. The memory stores a computer program, which, when executed by the processor, implements the sliding mode control method for a floating-based space robot with a fused decoupled dynamic model as described in the embodiments. It is understood that the electronic device may also include input / output (I / O) interfaces and communication components.

[0103] The processor is used to execute all or part of the steps in the sliding mode control method for a floating-based space robot with a fused decoupled dynamic model as described in the above embodiments. The memory is used to store various types of data, which may include, for example, instructions for any application or method in an electronic device, as well as application-related data.

[0104] The processor can be implemented as an Application Specific Integrated Circuit (ASIC), Digital Signal Processor (DSP), Programmable Logic Device (PLD), Field Programmable Gate Array (FPGA), controller, microcontroller, microprocessor, or other electronic components, and is used to execute the sliding mode control method for a floating-based space robot with a fused and decoupled dynamic model as described in the above embodiments.

[0105] Example 3:

[0106] This embodiment proposes a computer-readable storage medium that stores executable instructions. When these instructions are executed, if they are implemented as software functional units and sold or used as independent products, they can be stored in a computer-readable storage medium.

[0107] The computer software product is stored in a storage medium and includes several instructions to cause a computer device (which may be a personal computer, a server, or a network device, etc.) to execute all or part of the steps of the sliding mode control method for a floating base space robot with a fused decoupled dynamic model as described in the various embodiments of this application.

[0108] The aforementioned storage media include: flash memory, hard disks, multimedia cards, card-type memory (e.g., SD (Secure Digital Memory Card) or DX (Memory Data Register, MDR) memory), random access memory (RAM), static random-access memory (SRAM), read-only memory (ROM), electrically erasable programmable read-only memory (EEPROM), programmable read-only memory (PROM), magnetic storage, disks, optical discs, servers, APP (Application) app stores, and other media capable of storing program verification codes. These media store computer programs, which, when executed by a processor, can implement the various steps of the aforementioned sliding mode control method for floating-based space robots based on a fused and decoupled dynamic model.

[0109] Example 4:

[0110] This embodiment proposes a computer program product, including a computer program or instructions, which, when executed by a processor, implements the sliding mode control method for a floating-based space robot based on a fused and decoupled dynamic model.

[0111] Based on this understanding, the technical solution of this application, in essence, or the part that contributes to the prior art, or part of the technical solution, can be embodied in the form of a computer program product.

[0112] The various embodiments in this application are described in a progressive manner. The same or similar parts between the various embodiments can be referred to each other. Each embodiment focuses on describing the differences from other embodiments.

[0113] The scope of protection of this application is not limited to the embodiments described above. Obviously, those skilled in the art can make various modifications and variations to this disclosure without departing from the scope and spirit of this disclosure. If such modifications and variations fall within the scope of this disclosure and its equivalents, then the intent of this disclosure also includes these modifications and variations.

Claims

1. A sliding mode control method for a floating-based space robot that integrates a decoupled dynamic model, characterized in that, Includes the following steps: Acquire measurement signals from the end effector of the floating-based space robot, and establish contact determination index and floating-based stability index for the floating-based space robot; Based on the contact determination index and the floating base stability index, a logical switching index is constructed. A globally unified control law is constructed to determine the working mode of the floating-based space robot based on the logic switching index, and the floating-based space robot is controlled based on the globally unified control law.

2. The sliding mode control method for a floating-based space robot based on a fused decoupled dynamic model according to claim 1, characterized in that, The specific method for establishing the contact determination index and floating base stability index of the floating base space robot is as follows: The measurement signals from the end effector of the floating-based space robot include the forces and torques acting on its end effector. Based on the measurement signals acquired by the six-dimensional force / torque sensor, a dimensionless normalized contact determination index for the floating-based space robot is established. and floating base stability index As shown in the formula below: ； in, , These are the contact thresholds for force and torque, respectively. , These are the integral thresholds for the floating base attitude angle change error and the floating base attitude angle change error, respectively. For the force observation values ​​of the end effector of the floating-based space robot, For the observed torque values ​​of the end effector of the floating-based space robot, The first three values ​​of the error of the six-dimensional force / torque sensor represent the difference between the floating base attitude angular velocity and the expected value. Based on contact determination index and floating base stability index Build logical switching metrics As shown in the formula below: 。 3. The sliding mode control method for a floating-based space robot based on a fused decoupled dynamic model according to claim 2, characterized in that, The floating space robot operates in two modes: free flight mode and free float mode.

4. The sliding mode control method for a floating-based space robot based on a fused decoupled dynamic model according to claim 3, characterized in that, The operating mode of the floating-based space robot is set based on logical switching indicators. The specific method is as follows: When the logic switching index is not zero, the working mode of the floating base space robot is set to free flight mode. When the logic switching index is zero, the working mode of the floating base space robot is set to free floating mode.

5. The sliding mode control method for a floating-based space robot based on a fused decoupled dynamic model according to claim 4, characterized in that, Global unified control laws include full-dimensional sliding mode control laws and reduced-dimensional sliding mode control laws. As shown in the formula below: ； in, For full-dimensional sliding mode control law, This is a sliding mode control law for dimension reduction.

6. The sliding mode control method for a floating-based space robot based on a fused decoupled dynamic model according to claim 5, characterized in that, The specific method for controlling a floating space robot based on a globally unified control law is as follows: When the floating-based space robot is in free flight mode, it is controlled through a full-dimensional control mode. When the floating-based space robot operates in free-floating mode, it is controlled through a dimensionality reduction control mode.

7. The sliding mode control method for a floating-based space robot based on a fused decoupled dynamic model according to claim 6, characterized in that, The full-dimensional control mode includes: Design a fully robust sliding mode control law As shown in the formula below: ； Among them, positive definite matrix For linear feedback gain, For the sliding surface of the full-dimensional sliding mode controller, To predict the external force mapping term, For sliding mode gain, It is a positive definite smoothing factor matrix. For the differential of the full-dimensional state tracking error, It is a positive definite diagonal gain matrix. To lock space velocity, For the desired generalized velocity, the positive definite matrix Here is the static robust gain matrix used to cover the static uncertainties of the system; positive definite matrix. The linear dynamic compensation gain matrix is ​​a positive definite matrix. The nonlinear dynamic compensation gain matrix is ​​a positive definite matrix. The gain matrix for force measurement uncertainty; Predicting external force mapping terms For measurement signal The mapping of the first-order linear extrapolated predicted value is shown in the following formula: ； in, The predicted value is from a six-dimensional force / torque sensor. For predicting gain; The equivalent number of sampling steps corresponding to the time delay. For sensor time delay, The sampling period for the control system; For sensor force / torque increments; This is the velocity mapping matrix. For global mapping matrix, This is the end effector-to-robotic arm joint transformation matrix; Through the full-dimensional robust sliding mode control law By controlling the floating-based space robot, the control force rotation of the floating base and the joint control torque of the space robot in free flight mode are obtained.

8. The sliding mode control method for a floating-based space robot based on a fused decoupled dynamic model according to claim 7, characterized in that, The dimensionality reduction control mode includes: Set the base control force spinor to a zero vector; Fully robust sliding mode control law Integral gain matrix Linear feedback gain matrix Linear dynamic compensation gain matrix Nonlinear dynamic compensation gain matrix Force measurement uncertainty gain matrix It is divided into a main sub-block corresponding to the base momentum control channel and a main sub-block corresponding to the robotic arm joint control channel; A dimension-reduced robust sliding mode control law is constructed based on the master block corresponding to the base momentum control channel. As shown in the formula below: ； in, For the sliding surface of the dimension reduction sliding mode controller, To differentiate the state tracking error in a reduced dimension, The dimension-reduced positive definite diagonal gain matrix. To reduce the linear feedback gain of the sliding mode controller, To reduce sliding mode gain, The dimension-reduced positive definite smoothing factor matrix, For the dimension-reduced static robust gain matrix, For dimension reduction, linear dynamic compensation gain matrix, This is the gain matrix for dimensionality reduction and nonlinear dynamic compensation.

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