Space robot finite time anti-interference trajectory tracking control method based on performance constraint and actuator saturation

Abstract

The invention discloses a space robot finite time anti-interference trajectory tracking control method based on performance constraint and actuator saturation, and the method comprises the steps: firstly solving a state-space equation of a flexible joint free flight space robot, constructing a system error vector in combination with a finite time instruction filter and an anti-saturation auxiliary system, and carrying out the finite time instruction filter and anti-saturation auxiliary system; a novel asymmetric logarithmic obstacle Lyapunov function with an asymmetric fixed time constraint boundary is constructed; and finally, a novel finite time advanced activation anti-saturation auxiliary system and a finite time adaptive controller with a performance constraint effect are constructed, so that finite time anti-interference trajectory tracking control of the space robot is realized. According to the method, the influence of sudden disturbance is considered in the design of the flexible joint free flight space robot controller for the first time, and under the limitation of the saturation performance constraint of the actuator, the trajectory tracking rapidity and accuracy of the space robot are ensured; and the influence of sudden disturbance in a space robot system on the trajectory tracking transient performance can be effectively inhibited.

Description

Technical Field

[0001] The present invention belongs to the field of space robot control, and in particular relates to a finite-time anti-disturbance trajectory tracking control method for a space robot based on performance constraints and actuator saturation. Background Art

[0002] With the continuous expansion of space exploration, space robots have become a key tool for on-orbit servicing. In particular, flexible, articulated free-flying space robots, which combine the agility of spacecraft with the dexterous manipulation capabilities of robotic arms, have demonstrated a wide range of applications in complex space missions, including debris removal, refueling, and component upgrades.

[0003] However, these increasingly complex on-orbit services place higher demands on the trajectory tracking performance of flexible-jointed free-flying space robots. In practical manipulator systems, not only are performance constraints and actuator saturation issues limiting the trajectory tracking performance of flexible-jointed free-flying space robots, but inevitable collisions with space debris can also severely impact their transient trajectory tracking performance. Therefore, it is necessary to develop an effective trajectory tracking controller that can address both performance constraints and actuator saturation to improve the anti-interference capability of flexible-jointed space robots and cope with sudden disturbances.

[0004] In performance-constrained control schemes, constraint boundaries have a significant impact on the transient performance of the system. To address the limitations of constraint boundaries, including their dependence on the accuracy of the initial tracking error and deficiencies in convergence time, overshoot, and other aspects, some researchers have focused on improving constraint boundaries to achieve high-precision and flexible performance regulation. However, it is important to note that these boundaries are fixed after entering the steady-state phase. If the actual trajectory fluctuates due to sudden disturbances at this time, these boundaries will show significant deficiencies in improving transient performance. Given the prevalence of sudden disturbances in space environments, it is necessary to study strategies to reduce the impact of sudden disturbances on the transient performance of free-flying space robots.

[0005] Actuator saturation is a significant issue in space robot control, stemming from the inherent physical limitations of the actuators involved. The fundamental principle of anti-saturation control is to develop an anti-saturation auxiliary system and integrate auxiliary variables into the control law. Given the necessity of rapid manipulator maneuvers in practical tasks, rapid convergence of the tracking error is crucial. It is important to emphasize that the tracking error is linearly correlated with the auxiliary variables, making rapid convergence of the auxiliary variables crucial. However, current research has not fully considered the convergence time of the auxiliary variables, an issue that warrants further exploration.

[0006] There is an urgent need for a trajectory tracking control method for a flexible joint space robot that can cope with sudden disturbances while ensuring response speed and control accuracy, so that a flexible joint free-flying space robot with performance constraints and actuator saturation can achieve efficient and accurate trajectory tracking control under sudden disturbances. However, there is no relevant description in the existing technology. Summary of the Invention

[0007] In response to the above problems, the purpose of the present invention is to provide a finite-time anti-disturbance trajectory tracking control method for a space robot based on performance constraints and actuator saturation, so as to ensure that under sudden disturbances, the space robot system with performance constraints and actuator saturation can quickly and accurately achieve trajectory tracking control.

[0008] The specific technical solutions for achieving the purpose of the present invention are as follows:

[0009] A finite-time disturbance rejection trajectory tracking control method for a space robot based on performance constraints and actuator saturation includes the following steps:

[0010] Step 1: Based on the parameters of the flexible joint free-flight space robot, a dynamic model of the flexible joint space robot system considering actuator saturation is constructed and converted into a state space equation of the flexible joint free-flight space robot;

[0011] Step 2: Combine the finite time command filter and the anti-saturation auxiliary system to construct the system error vector;

[0012] Step 3: Construct a new asymmetric logarithmic barrier Lyapunov function with an asymmetric fixed time constraint boundary;

[0013] Step 4. Based on the state space equation of step 1, the error vector of step 2, and the new asymmetric logarithmic obstacle Lyapunov function with asymmetric fixed time boundary of step 3, a new finite-time advance activation anti-saturation auxiliary system and a finite-time adaptive controller with performance constraints are constructed under the framework of finite-time instruction filtering backstepping method to realize finite-time anti-disturbance trajectory tracking control of space robots.

[0014] Compared with the prior art, the present invention has the following beneficial effects:

[0015] (1) The novel asymmetric logarithmic obstacle Lyapunov function constructed in the space robot trajectory tracking control method of the present invention broadens the limitations of the traditional logarithmic obstacle Lyapunov function in the form of a piecewise function and can be applied to both constrained and unconstrained situations;

[0016] (2) The novel asymmetric fixed-time boundary constructed by the present invention can effectively suppress the influence of sudden disturbances on the transient performance of free-flying space robots. In the convergence phase of the boundary, the trajectory deviation caused by sudden disturbances is suppressed by designing a translatable single-peak boundary. In the steady-state phase of the boundary, a dynamically bounded adaptive compensation strategy is adopted to autonomously adjust the boundary according to the tracking error, thereby suppressing the influence of sudden disturbances on the transient performance of trajectory tracking.

[0017] (3) The novel limited-time advance activation anti-saturation auxiliary system constructed by the present invention introduces a virtual saturation link, sets the virtual saturation limit lower than the actual saturation limit, and activates the anti-saturation auxiliary system in advance. This can not only effectively solve the actuator saturation problem, but also enable the free-flying space robot to have better transient performance;

[0018] (4) The present invention is the first to consider the influence of sudden disturbances in the design of a flexible joint free-flying space robot controller. Under the constraints of actuator saturation and performance constraints, it ensures the rapidity and accuracy of the space robot's trajectory tracking while effectively suppressing the influence of sudden disturbances in the space robot system on the transient performance of trajectory tracking.

[0019] The present invention will be further described below with reference to specific embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 This is a flow chart of the finite-time anti-disturbance trajectory tracking control method for a space robot based on performance constraints and actuator saturation of the present invention.

[0021] Figure 2 This is a control block diagram of a trajectory tracking control method for a flexible joint free-flying space robot with performance constraints and actuator saturation under sudden disturbances in an embodiment of the present invention.

[0022] Figure 3 Schematic diagram of the structure of a space robot in an embodiment of the present invention.

[0023] Figure 4 The simulation results of the trajectory tracking error of the space robot system in different initial states in scenario A of the embodiment of the present invention are shown in FIG. (a) is z 11 -z 13 Error curve of z 14 -z 115 Error curve diagram.

[0024] Figure 5 These are the control torque simulation results of the space robot system in different initial states in scenario A of the embodiment of the present invention, where (a) is the control torque diagram of the base spacecraft posture, and (b) is the control torque diagram of the joint motor.

[0025] Figure 6 This is a simulation result diagram comparing the control torque of the space robot under the action of the anti-saturation auxiliary system activated in advance within a limited time and the anti-saturation auxiliary system activated immediately within a limited time in the embodiment scenario B of the present invention, where (a) is the control torque diagram of the base spacecraft posture, and (b) is the control torque diagram of the joint motor.

[0026] Figure 7-9 The following is a comparison of the simulation results of the trajectory tracking error of the space robot under sudden disturbances occurring in three different time periods before time T in scenario C of the embodiment of the present invention, where (a) is z 11 -z 13 Error curve of z 14 -z 115 Error curve diagram.

[0027] Figure 10 The simulation results of the space robot trajectory tracking error comparison under the sudden disturbance after time T in the scenario D of the embodiment of the present invention are shown in FIG. (a) is the trajectory tracking error of the space robot under the sudden disturbance after time T, where (b) is the trajectory tracking error of the space robot under the sudden disturbance after time T 11 -z 13 The error curve of z is shown in (b), and the error curve of z is shown in (b) under the action of the constant lower bound. 14 -z 115 Error curve diagram. DETAILED DESCRIPTION

[0028] Example

[0029] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. The described embodiments are only part of the embodiments of the present invention, not all of the embodiments. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making any creative efforts are within the scope of protection of the present invention.

[0030] As used in this application and the claims, the words "a," "an," "an," and / or "the" are not intended to refer to the singular but may include the plural unless the context clearly indicates otherwise. Generally speaking, the terms "comprises" and "include" only indicate the inclusion of the steps or elements specifically identified, and these steps and elements do not constitute an exclusive list. A method or apparatus may also include other steps or elements.

[0031] Unless otherwise specifically stated, the relative arrangement of the parts and steps, numerical expressions and numerical values set forth in these embodiments do not limit the scope of the present application. At the same time, it should be understood that, for ease of description, the sizes of the various parts shown in the drawings are not drawn according to actual proportional relationships. The techniques, methods and equipment known to those of ordinary skill in the relevant art may not be discussed in detail, but where appropriate, the techniques, methods and equipment should be considered as part of the authorization specification. In all examples shown and discussed here, any specific values should be interpreted as being merely exemplary and not as limitations. Therefore, other examples of the exemplary embodiments may have different values. It should be noted that similar numbers and letters represent similar items in the following figures, and therefore, once an item is defined in one figure, it does not need to be further discussed in subsequent figures.

[0032] Combine Figure 1 and Figure 2 , a finite-time disturbance rejection trajectory tracking control method for a space robot based on performance constraints and actuator saturation, comprising the following steps:

[0033] Step 1: Based on the parameters of the flexible joint free-flight space robot, a dynamic model of the flexible joint space robot system considering actuator saturation is constructed and converted into the state space equation of the flexible joint free-flight space robot:

[0034] Step 1-1: Based on the Lagrangian modeling method, construct a dynamic model of a flexible joint free-flying space robot:

[0035]

[0036] Where M(q)∈R 5×5 represents the inertia matrix of the flexible joint free-flying space robot, Denotes the Coriolis force and centripetal force matrix of the flexible joint free-flying space robot, K = diag{K1,K2}∈R 2×2 represents the joint stiffness matrix of the two joints of the manipulator arm of the space robot, J m =diag{J m1 ,J m2}∈R 2×2 Represents the inertia matrix of the two joint motors of the space robot's manipulator arm, q = [r bx ,r by ,q b ,q m T ] T ∈R 5×5 represents the position vector of the flexible joint free-flying space robot, r bx ,r byIndicates the position of the base spacecraft of the space robot on the plane x, y axis, q b ,q m =[q1,q2] T They represent the attitude angle of the base spacecraft and the joint angle of the robotic arm, q1 represents the joint angle of the first joint of the robotic arm, q2 represents the joint angle of the second joint of the robotic arm, θ=[θ1,θ2] T ∈R 2 , Respectively represent the motor rotation angle and angular acceleration of the two manipulator arms of the space robot, τ=[τ0 T ,τ m T ] T ∈R 5 Represents the control torque, τ0=[τ bx ,τ by ,τ b ] T , τ bx ,τ by represents the position control torque of the base spacecraft, τ b represents the attitude control torque of the base spacecraft, τ m =[τ m1 ,τ m2 ] T represents the control torque of the two joint motors of the space robot's manipulator arm, τ d represents uncertainty disturbance;

[0037] The space robot in this embodiment is as follows Figure 3 As shown, the inertia matrix M(q), the Coriolis force and centripetal force matrix Joint stiffness matrix K = diag{K1, K2}, motor inertia matrix J m =diag{J m1 ,J m2} is as follows:

[0038]

[0039]

[0040] where s b =sin(q b ), s b1 =sin(q b +q1),s b12 =sin(q b +q1+q2), c b =cos(q b ), c b1 =cos(q b +q1), cb12 =cos(q b +q1+q2).

[0041] Step 1-2: Based on the dynamic model of the flexible joint free-flying space robot, determine its state space equation:

[0042] The system state of the flexible joint free-flying space robot is expressed as:

[0043]

[0044] Then the state space equation of the flexible joint free-flying space robot system is:

[0045]

[0046] Among them, K b =diag{1,1,1,K1,K2}, a1=diag{0,0,0,1,1}, a2=[0,I2] T , a3=diag{1,1,1,0,0}, d=M -1 τ d , are intermediate variables;

[0047] Steps 1-3: Set limits on the jets and motors of the base spacecraft and the joint motors of the robotic arm of the flexible joint free-flying space robot:

[0048]

[0049] Among them, τ i (i=1,2,3,4,5) represents the nominal control torque calculated by the controller, τ maxi It is a positive constant, indicating the maximum control torque that can be provided.

[0050] Step 2: To address the saturation characteristics of the space robot system actuator and the "differential explosion" problem of the virtual control law in the backstepping controller design, this solution combines a finite-time command filter and an anti-saturation auxiliary system to construct the system error vector:

[0051] Step 2-1: Construct a finite time instruction filter:

[0052]

[0053] Among them, α ir (i=1,2,3)∈R n represents the input signal of the finite time command filter, η1 and ψ are the output signals of the filter, η1 = α ic , α icis the finite time instruction filter for α i The tracking variable It is right The observed variables, R1, R2 represent the filter parameters,

[0054] Step 2-2: Determine the compensation error variable z of the flexible joint free-flying space robot system based on the constructed finite-time command filter i (i=1,2,3,4), that is, the state error variable in the 4-step backstepping method:

[0055]

[0056] Among them, γ i (i=1,2,3) represents the filter error compensation variable, η b ,η m represents the anti-saturation auxiliary variable, q d represents the expected trajectory, α ic (i=1,2,3) represents the output signal of the finite time instruction filter, e i (i=1,2,3,4) represents the state error of the flexible joint free-flying space robot;

[0057] Step 3: The traditional asymmetric time-varying logarithmic Lyapunov function has limited application scope and lacks versatility. Its time-varying boundary cannot effectively deal with the sudden disturbances that the space robot may encounter during operation. Therefore, this solution constructs a new asymmetric logarithmic obstacle Lyapunov function with an asymmetric fixed time constraint boundary to ensure that the system's trajectory tracking control has excellent transient performance under sudden disturbance conditions:

[0058] Step 3-1: Construct a new asymmetric logarithmic barrier Lyapunov function:

[0059]

[0060] Among them, k ui (t), k 1i (t) is the fixed time constraint boundary, q ci With z 1i (i=1,2,3,4,5) and z 1i (0) is positively correlated with z 1i (0) means z 1i The initial value of q ci Switch variables for boundaries, specifically:

[0061] For z 1i (0)>0, yes

[0062]

[0063] For z 1i (0)<0, yes

[0064]

[0065] Step 3-2: Construct a new asymmetric fixed time constraint boundary:

[0066]

[0067] Among them, ρ ui (t) and ρ 1i (t) represent the upper and lower bounds of the asymmetric fixed-time convergence function, respectively, which are:

[0068]

[0069] in, is the intermediate variable, P max represents the maximum value of P(t), ρ ∞ui and ρ ∞1i Respectively represent ρ ui (t) and ρ 1i The steady-state value of (t), c is a positive constant, which determines ρ ui The convergence rate of (t), c u0 and c 10 is a positive constant used to adjust ρ ui (t) and ρ 1i (t) is the initial value, T represents the convergence time of the boundary function, μ1 and μ2 are positive constants, b i Represents the boundary compensation term: the boundary compensation term b i To deal with sudden interference that occurs after time T, specifically:

[0070]

[0071] φ 2i =φ 1i (φ 3i -1)+1,

[0072]

[0073]

[0074] Among them, r1 is a positive constant, φ zi represents z 1i The degree of deviation from the safe area, φ 2i is an auxiliary variable to determine whether the torque is saturated. If φ 2i= 0, indicating that the error does not saturate after crossing the safety zone. It can be inferred that the system still has the ability to self-regulate, so there is no need to compensate for the boundary. In other cases, that is, φ 2i =1, use b i (t) Dynamic and bounded compensation of the boundary, φ 3i To judge z 1i Auxiliary variable indicating whether the predetermined safety area has been exceeded.

[0075] Step 4. For a flexible joint free-flying space robot with performance constraints and actuator saturation under sudden disturbances, based on the state space equation of step 1, the error vector of step 2, and the new asymmetric logarithmic obstacle Lyapunov function with asymmetric fixed time boundary of step 3, a new finite-time advance activation anti-saturation auxiliary system and a finite-time adaptive controller with performance constraints are constructed within the framework of the finite-time command filter backstepping method to realize finite-time anti-disturbance trajectory tracking control of the space robot:

[0076] Design the virtual control law α1 and the filter error compensation variable γ1:

[0077]

[0078] Among them, k1, c1 are positive constants, κ1=[κ 11 ,κ 12 ,κ 13 ,κ 14 ,κ 15 ] T ,

[0079]

[0080] All are intermediate variables;

[0081] Constructing the barrier Lyapunov function

[0082]

[0083] Substituting the virtual control law α1 and the filter error compensation variable γ1 into the obstacle Lyapunov function V1, we can obtain

[0084]

[0085] When z2=0, z1 converges, so it is necessary to ensure the convergence of z2 to make the system stable;

[0086] Design virtual auxiliary control law τ u , filtering error compensation variable γ2, anti-saturation auxiliary variable η b , Adaptive Law Actual control torque of base spacecraft And the virtual control law α2:

[0087]

[0088] Where k2, c2, ξ, k5 are positive constants, and p = [Γ1, Γ2, Γ3, Γ4, Γ5] T , It represents the control torque after the virtual saturation link acts;

[0089] Constructing Lyapunov function

[0090]

[0091] The virtual auxiliary control law τ u , filtering error compensation variable γ2, anti-saturation auxiliary variable η b , Adaptive Law Actual control torque of base spacecraft And the virtual control law α2 is substituted into the Lyapunov function V2 to obtain:

[0092]

[0093] in In order to ensure the convergence of z2, it is necessary to ensure the convergence of z3;

[0094] Design the virtual control law α3 and the filter error compensation variable γ3:

[0095]

[0096] Among them, k3, c3 are positive constants;

[0097] Constructing Lyapunov function

[0098]

[0099] Substituting the virtual control law α3 and the filter error compensation variable γ3 into the Lyapunov function V3, we can get

[0100]

[0101] In order to ensure the convergence of z3, the next step needs to be designed to ensure the convergence of z4;

[0102] Design of anti-saturation auxiliary variable η m And the actual control torque of the motor

[0103]

[0104] Among them, k4, c4 are positive constants, Indicates the control force acting through the virtual saturation link;

[0105] Constructing Lyapunov function

[0106]

[0107] The anti-saturation auxiliary variable η m And the actual control torque of the robot arm motor Substituting into the Lyapunov function V4 we get:

[0108]

[0109] in

[0110] In summary, by designing the control torque of the base spacecraft Actual control torque of the robotic arm motor Virtual control law α i (i=1,2,3), γ i (i=1,2,3) and anti-saturation auxiliary variable η b ,η m , to ensure compensation error variable z i Convergence of (i=1,2,3,4).

[0111] In this embodiment, the physical parameters of the flexible joint space robot are shown in the following table:

[0112] Table 1 Physical parameters of flexible joint space robot

[0113]

[0114]

[0115] The expected trajectory of the system is: q d =[0m,0m,0.1sin(t)rad,0.1sin(t)rad,0.1sin(t)rad]; the finite time command filter parameters are: R1=2000, R2=0.8; the finite time adaptive controller parameters are: k1=k2=2, k3=k4=40, c1=2, c2=c3=c4=40, σ=0.8; the asymmetric fixed time constraint boundary parameters are: c=1, c u0 =0.6,ρ ∞ui =0.12, c 10 =0.5, μ1=μ2=2, ρ ∞1i=0.12, T=2. The boundary compensation parameters are: r1=0.8, h=0.02. Set the actual actuator saturation limit respectively with virtual actuator saturation limit denote the actual actuator saturation limits of the base and the manipulator, respectively, They represent the virtual actuator saturation limits of the base and the manipulator, respectively. To meet the physical limitations of the actual space robot actuators, the virtual saturation limits must be lower than the actual saturation limits, specifically:

[0116]

[0117] Four different scenarios were simulated based on MATLAB, and the simulation results were as follows: Figure 4-10 shown.

[0118] Specifically, in scenario A, the control performance of the free-flying space robot under three initial states is demonstrated. In scenario B, the performance of z1 under the finite-time advance activation of the anti-saturation device and the finite-time immediate activation of the anti-saturation auxiliary system are compared; in scenario C, for the sudden disturbances occurring in three different periods before time T, the peak time of the lower boundary is changed by changing the parameters μ1 and μ2 to suppress the influence of sudden disturbances on the trajectory tracking performance, and the changes of z1 under the asymmetric fixed time constraint boundary and the ordinary performance constraint boundary are compared; in scenario D, for the sudden disturbances after time T, the performance of z1 under the asymmetric fixed time boundary with compensation and without compensation is compared. The simulation results are shown as follows: Figure 4-10 shown.

[0119] Scenario A: Set three system initial states for comparison:

[0120] Initial state 1: q(0) = [0.1m, 0.1m, 0.1rad, 0.1rad, 0.1rad];

[0121] Initial state 2: q(0) = [0.15m, 0.15m, 0.15rad, 0.15rad, 0.15rad];

[0122] Initial state 3: q(0) = [0.2m, 0.2m, 0.2rad, 0.2rad, 0.2rad].

[0123] Figure 4 (a) and Figure 4 (b) shows the trajectory tracking results of the base position and attitude angle and the manipulator joint angle under different initial states. Despite the performance constraints and actuator saturation, the free-flying space robot still shows excellent fast convergence performance. In addition, by observing Figure 5 (a) and Figure 5(b) It can be seen that the larger the initial error, the larger the initial control torque. The simulation in scenario A verifies the finite-time convergence performance of the controller designed in this invention under different initial states, facing performance constraints and actuator saturation, and also demonstrates the controller's adaptability.

[0124] Scenario B: Combination Figure 6 , the initial state is set to q(0) = [0.1m, 0.1m, 0.1rad, 0.1rad, 0.1rad]. In this scenario, the present invention compares the control torque of a free-flying space robot under the finite-time advance activation anti-saturation auxiliary system and the finite-time immediate activation anti-saturation auxiliary system. Compared with the finite-time immediate activation anti-saturation auxiliary system, the finite-time advance activation anti-saturation auxiliary system can make the control torque exit the saturation state faster, which shows that the finite-time advance activation anti-saturation auxiliary system has advantages in improving the dynamic response characteristics of the system.

[0125] Scenario C: The initial state is set to q(0) = [0.1m, 0.1m, 0.1rad, 0.1rad, 0.1rad]. Sudden disturbances τ are added within 0.2-0.7s, 0.5-1s, and 1-1.7s. d =[2,2,2,1,1](N·m), setting μ1=μ2=5, μ1=μ2=2, and μ1=μ2=0.6 respectively, and comparing the z1 variable of the flexible joint free-flying space robot under the asymmetric fixed time constraint boundary proposed in the present invention and the common performance constraint boundary. The common preset performance function boundary is as follows:

[0126] ρ(t)=-(ρ0-ρ ∞ )e -Lt -ρ ∞

[0127] Where ρ0=0.6,ρ ∞ = 0.12, L = 4. Due to the unique form of the asymmetric fixed time constraint boundary, it is more effective in suppressing trajectory tracking deviations under sudden disturbances compared to the conventional preset performance function boundary, mainly manifested in smaller overshoot and shorter recovery time.

[0128] Scenario D: The initial state is set to q(0) = [0.1m, 0.1m, 0.1rad, 0.1rad, 0.1rad]. A sudden disturbance τ is added within 2-2.01 seconds. d =[8,8,8,4,4](N·m). Figure 8 It is clearly seen in (b) that z 14 and z 15 The boundary will shrink to cope with the sudden disturbance z 14 and z 15The case of deviation from the origin. z under the asymmetric fixed time constraint boundary without compensation 14 and z 15 In contrast, z under the asymmetric fixed time constraint boundary with compensation 14 and z 15 It has faster convergence speed and lower overshoot.

[0129] The method proposed in the present invention ensures the robustness of the flexible joint space robot system when it is suddenly disturbed after time T.

[0130] The above-described embodiments merely represent several implementation methods of the present application. While the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that a person skilled in the art could make various modifications and improvements without departing from the spirit of the present application, all of which fall within the scope of protection of the present application. Therefore, the scope of protection of the present patent application shall be determined by the appended claims.

Claims

1. A finite-time disturbance rejection trajectory tracking control method for a space robot based on performance constraints and actuator saturation, characterized in that: The following steps are involved: Step 1: Based on the parameters of the flexible joint free-flight space robot, a dynamic model of the flexible joint space robot system considering actuator saturation is constructed and converted into a state space equation of the flexible joint free-flight space robot; Step 2: Combine the finite time command filter and the anti-saturation auxiliary system to construct the system error vector; Step 3: Construct a new asymmetric logarithmic barrier Lyapunov function with an asymmetric fixed time constraint boundary; Step 4. Based on the state space equation of step 1, the error vector of step 2, and the new asymmetric logarithmic obstacle Lyapunov function with asymmetric fixed time boundary of step 3, a new finite-time advance activation anti-saturation auxiliary system and a finite-time adaptive controller with performance constraints are constructed under the framework of finite-time instruction filtering backstepping method to realize finite-time anti-disturbance trajectory tracking control of space robots.

2. The finite-time disturbance rejection trajectory tracking control method for a space robot based on performance constraints and actuator saturation according to claim 1 is characterized in that: The state space equation of the flexible joint space robot in step 1 is specifically: Step 1-1: Based on the Lagrangian modeling method, construct a dynamic model of a flexible joint free-flying space robot: Where M(q)∈R 5×5 represents the inertia matrix of the flexible joint free-flying space robot, Denotes the Coriolis force and centripetal force matrix of the flexible joint free-flying space robot, K = diag{K1,K2}∈R 2×2 represents the joint stiffness matrix of the two joints of the manipulator arm of the space robot, J m =diag{J m1 ,J m2 }∈R 2×2 Represents the inertia matrix of the two joint motors of the space robot's manipulator arm, q = [r bx ,r by ,q b ,q m T ] T ∈R 5×5 represents the position vector of the flexible joint free-flying space robot, r bx ,r by Indicates the position of the base spacecraft of the space robot on the plane x, y axis, q b ,q m =[q1,q2] T They represent the attitude angle of the base spacecraft and the joint angle of the robotic arm, q1 represents the joint angle of the first joint of the robotic arm, q2 represents the joint angle of the second joint of the robotic arm, θ=[θ1,θ2] T ∈R 2 , Respectively represent the motor rotation angle and angular acceleration of the two manipulator arms of the space robot, τ=[τ0 T ,τ m T ] T ∈R 5 Represents the control torque, τ0=[τ bx ,τ by ,τ b ] T , τ bx ,τ by represents the position control torque of the base spacecraft, τ b represents the attitude control torque of the base spacecraft, τ m =[τ m1 ,τ m2 ] T represents the control torque of the two joint motors of the space robot's manipulator arm, τ d represents uncertainty disturbance; Step 1-2: Based on the dynamic model of the flexible joint free-flying space robot, determine its state space equation: The system state of the flexible joint free-flying space robot is expressed as: Then the state space equation of the flexible joint free-flying space robot system is: Among them, K b =diag{1,1,1,K1,K2}, a1=diag{0,0,0,1,1}, a2=[0,I2] T , a3=diag{1,1,1,0,0}, d=M -1 τ d , are intermediate variables; Steps 1-3: Set limits on the jets and motors of the base spacecraft and the joint motors of the robotic arm of the flexible joint free-flying space robot: Among them, τ i (i=1,2,3,4,5) represents the nominal control torque calculated by the controller, τ maxi It is a positive constant, indicating the maximum control torque that can be provided.

3. The finite-time disturbance rejection trajectory tracking control method for a space robot based on performance constraints and actuator saturation according to claim 2 is characterized in that: The system error vector in step 2 is specifically: Step 2-1: Construct a finite time instruction filter: Among them, α ir (i=1,2,3)∈R n represents the input signal of the finite time command filter, η1 and ψ are the output signals of the filter, η1 = α ic , α ic is the finite time instruction filter for α i The tracking variable It is right The observed variables, R1, R2 represent the filter parameters, Step 2-2: Determine the compensation error variable z of the flexible joint free-flying space robot system based on the constructed finite-time command filter i (i=1,2,3,4): Among them, γ i (i=1,2,3) represents the filter error compensation variable, η b ,η m represents the anti-saturation auxiliary variable, q d represents the expected trajectory, α ic (i=1,2,3) represents the output signal of the finite time instruction filter, e i (i=1,2,3,4) represents the state error of the flexible joint free-flying space robot.

4. The finite-time disturbance rejection trajectory tracking control method for a space robot based on performance constraints and actuator saturation according to claim 1 is characterized in that: The construction of a new asymmetric logarithmic barrier Lyapunov function with an asymmetric fixed time constraint boundary in step 3 is specifically as follows: Step 3-1: Construct a new asymmetric logarithmic barrier Lyapunov function: Among them, k ui (t), k 1i (t) is the fixed time constraint boundary, q ci With z 1i (i=1,2,3,4,5) and z 1i (0) is positively correlated with z 1i (0) means z 1i The initial value of q ci Switch variables for boundaries, specifically: For z 1i (0)〉0, yes For z 1i (0)<0, yes Step 3-2: Construct a new asymmetric fixed time constraint boundary: Among them, ρ ui (t) and ρ 1i (t) represent the upper and lower bounds of the asymmetric fixed-time convergence function, respectively, which are: in, is the intermediate variable, P max represents the maximum value of P(t), ρ ∞ui and ρ ∞1i Respectively represent ρ ui (t) and ρ 1i The steady-state value of (t), c is a positive constant, which determines ρ ui The convergence rate of (t), c u0 and c 10 is a positive constant used to adjust ρ ui (t) and ρ 1i (t) is the initial value, T represents the convergence time of the boundary function, μ1 and μ2 are positive constants, b i Represents the boundary compensation term.

5. The finite-time disturbance rejection trajectory tracking control method for a space robot based on performance constraints and actuator saturation according to claim 3 is characterized in that: The boundary compensation term b i To deal with sudden interference that occurs after time T, specifically: f 2i =φ 1i (f 3i -1)+1, Among them, r1 is a positive constant, φ zi represents z 1i The degree of deviation from the safe area, φ 2i is an auxiliary variable to determine whether the torque is saturated, φ 3i To judge z 1i Auxiliary variable indicating whether the predetermined safety area has been exceeded.

6. The finite-time disturbance rejection trajectory tracking control method for a space robot based on performance constraints and actuator saturation according to claim 3 is characterized in that: The construction of a novel finite-time advance activation anti-saturation auxiliary system and a finite-time adaptive controller with performance constraints in step 4 is specifically as follows: Design the virtual control law α1 and the filter error compensation variable γ1: where k1 and c1 are positive constants, κ1 = [κ 11 , κ 12 , κ 13 , κ 14 , κ 15 T ,​ All are intermediate variables; Constructing the barrier Lyapunov function Substituting the virtual control law α1 and the filter error compensation variable γ1 into the obstacle Lyapunov function V1, we can obtain When z2=0, z1 converges, so it is necessary to ensure the convergence of z2 to make the system stable; Design virtual auxiliary control law τ u , filtering error compensation variable γ2, anti-saturation auxiliary variable η b , Adaptive Law Actual control torque of base spacecraft And the virtual control law α2: Where k2, c2, ξ, k5 are positive constants, and p = [Γ1, Γ2, Γ3, Γ4, Γ5] T , It represents the control torque after the virtual saturation link acts; Constructing Lyapunov function The virtual auxiliary control law τ u , filtering error compensation variable γ2, anti-saturation auxiliary variable η b , Adaptive Law Actual control torque of base spacecraft And the virtual control law α2 is substituted into the Lyapunov function V2 to obtain: in In order to ensure the convergence of z2, it is necessary to ensure the convergence of z3; Design the virtual control law α3 and the filter error compensation variable γ3: Among them, k3, c3 are positive constants; Constructing Lyapunov function Substituting the virtual control law α3 and the filter error compensation variable γ3 into the Lyapunov function V3, we can get In order to ensure the convergence of z3, the next step needs to be designed to ensure the convergence of z4; Design of anti-saturation auxiliary variable η m And the actual control torque of the motor Among them, k4, c4 are positive constants, Indicates the control force acting through the virtual saturation link; Constructing Lyapunov function The anti-saturation auxiliary variable η m And the actual control torque of the robot arm motor Substituting into the Lyapunov function V4 we get: in In summary, by designing the control torque of the base spacecraft Actual control torque of the robotic arm motor Virtual control law α i (i=1,2,3), γ i (i=1,2,3) and anti-saturation auxiliary variable η b ,η m , to ensure compensation error variable z i Convergence of (i=1,2,3,4).

7. A finite-time disturbance rejection trajectory tracking control system for a space robot based on performance constraints and actuator saturation, characterized in that: Includes the following modules: State space equation module: used to construct the dynamic model of the flexible joint free flight space robot system and convert it into the state space equation of the flexible joint free flight space robot system; System error vector module: used to combine the finite time command filter and the anti-saturation auxiliary system to construct the system error vector; Asymmetric fixed-time convergence function boundary module: used to ensure the transient performance of trajectory tracking of flexible joint space robots under sudden disturbances; Anti-saturation auxiliary system module: used to construct a layered sliding surface with fixed time convergence characteristics; Finite-time adaptive controller module: used to build a flexible joint free-flight space robot controller for trajectory tracking control.

8. A computer device comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein: When the processor executes the computer program, the steps of the method according to any one of claims 1 to 6 are implemented.

9. A computer storable medium having a computer program stored thereon, characterized in that: When the computer program is executed by a processor, the steps of the method according to any one of claims 1 to 6 are implemented.

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