Anti-saturation control method for non-cooperative spacecraft rendezvous system with sensor fault
By designing an anti-saturation controller, the problems of sensor failure and actuator saturation in non-cooperative spacecraft rendezvous systems were solved, achieving high-precision control.
Patent Information
- Application Number
- CN202510461281.9
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-04-14
- Publication Date
- 2025-08-01
AI Technical Summary
Existing control methods for non-cooperative spacecraft rendezvous systems fail to effectively address sensor failures and actuator saturation, resulting in low control accuracy and complex controller design.
By employing state observers, sliding mode control theory, and the full-drive system approach, an anti-saturation controller is designed. By establishing a second-order full-drive system model and combining a state observer and an anti-saturation compensator, effective control of the non-cooperative spacecraft rendezvous system is achieved.
It achieves effective control under sensor failure and actuator saturation conditions, improves control accuracy, and simplifies the controller design process.
Smart Images
Figure CN120406538A_ABST
Abstract
Description
Technical Field
[0001] The present invention belongs to the field of aerospace control technology, and relates to the control of a non-cooperative spacecraft rendezvous system, specifically to an anti-saturation control method for a non-cooperative spacecraft rendezvous system with sensor faults. Background Art
[0002] In recent years, the scope of space on-orbit service missions has expanded from conventional missions such as spacecraft on-orbit maintenance and large satellite assembly to new mission directions such as active space debris removal, tumbling spacecraft capture, and enemy spacecraft tracking. The characteristic of these new missions is that their service objects are mostly non-cooperative targets. Since non-cooperative targets cannot provide key information such as their own orbital states, the control of the rendezvous system is more challenging. Therefore, the research on the control of non-cooperative spacecraft rendezvous systems has very important theoretical significance and application value.
[0003] At present, most of the control problems of non-cooperative spacecraft rendezvous systems are solved by using state-space methods. Some of these methods perform equivalent linearization on the system, which results in inaccurate control models and affects the control accuracy of the system. Another part of the methods use non-linear control methods to handle non-linear terms, but these methods are not universal, mostly require special forms or meet special conditions, and the controller design process is very complex. Therefore, it is necessary to develop a new control method to effectively control the non-cooperative spacecraft rendezvous system and improve the control accuracy. Summary of the Invention
[0004] Aiming at the deficiencies of the prior art, the present invention proposes an anti-saturation control method for a non-cooperative spacecraft rendezvous system with sensor faults. Based on the state observer, sliding mode control theory, and fully actuated system method, considering the situation of sensor faults, external disturbances, and actuator saturation in the system, an anti-saturation controller is designed to achieve effective control of the non-cooperative spacecraft rendezvous system, which is applicable to the autonomous rendezvous of spacecraft and non-cooperative targets. [[ID=IS]]
[0005] The anti-saturation control method for a non-cooperative spacecraft rendezvous system with sensor faults is as follows:
[0006] Step 1: Establish a second-order fully actuated system model of the non-cooperative spacecraft rendezvous system
[0007] Considering the sensor fault δ(t), actuator saturation sat(u), and external disturbance d, establish a second-order fully actuated system model of the non-cooperative spacecraft rendezvous system:
[0008]
[0009]
[0010] where θ = [ρεβ] T is the system state vector, ρ represents the relative distance between the tracking spacecraft and the target spacecraft, and ε and β represent the pitch angle and yaw angle of the tracking direction of the tracking spacecraft relative to the inertial coordinate system, respectively. u=[u1 u2 u3] T =[-a x -a y -a z ] T is the control input vector, a x 、a y 、a z Respectively represent the acceleration of the tracking spacecraft in the X-axis, Y-axis and Z-axis directions. y is the measurement output. μ is the gravitational constant, R ch =[R x R y R z ] T is the vector from the center of the Earth to the center of mass of the tracking spacecraft. t represents time, u max and u min are the maximum and minimum values of the control input, respectively. represent the first derivative and the second derivative respectively, and || || represents the 2-norm.
[0011] definition f=G -1 (θ)d, the above second-order all-wheel drive system model is rewritten as:
[0012]
[0013] G -1 (θ) represents the inverse of the matrix G(θ).
[0014] Step 2: State Observer Design
[0015] definition Design the following state observer to estimate the system state vector θ and external disturbance d:
[0016]
[0017] in, are the estimated values of Z1, Z2, and f, respectively. is the observer parameter matrix to be designed.
[0018] Step 3: Anti-saturation controller design
[0019] Design the sliding surface function s as follows:
[0020]
[0021] Among them, A0 and A1 are the parameter matrices to be designed.
[0022] Design an anti - saturation compensator, whose dynamic equation is:
[0023]
[0024] where υ is the compensator state, is the input error, γ and l1 are positive parameters, and 0 < γ ≤ 0.1.
[0025] Combine the sliding - mode surface function with the anti - saturation compensator to design the anti - saturation controller u for the second - order fully - actuated system model:
[0026]
[0027] where l2 is a positive parameter, and sgn(·) represents the sign function.
[0028] Step 4. Stability analysis of the closed - loop system
[0029] Analyze the stability conditions of the closed - loop system, solve the parameter matrix to be designed, and obtain the anti - saturation controller u for the second - order fully - actuated system model, so as to realize the anti - saturation control of the non - cooperative spacecraft rendezvous system.
[0030] The present invention has the following beneficial effects:
[0031] Aiming at the problem that the existing control methods for non - cooperative spacecraft rendezvous systems do not consider the influence of sensor failures and actuator saturation on the system, the present invention establishes a second - order fully - actuated system model for non - cooperative spacecraft rendezvous systems. On this basis, a state observer is designed, and then an anti - saturation controller with a state observer and an anti - saturation compensator is designed by using integral sliding - mode control and fully - actuated system methods, enabling the spacecraft to rendezvous with non - cooperative targets, thus filling the gap in the existing technology. Using this method, effective control of non - cooperative spacecraft rendezvous systems with sensor failures, external disturbances, and actuator saturation can be achieved, and the controller design is simple, which can meet the actual usage requirements. Description of the drawings
[0032] Figure 1 Shows the relative position change between spacecrafts in the embodiment;
[0033] Figure 2 Shows the relative velocity change between spacecrafts in the embodiment;
[0034] Figure 3 Shows the change of the control input in the embodiment. Detailed implementation manners
[0035] The following further explains the present invention with reference to the drawings;
[0036] Anti-saturation control method for non-cooperative spacecraft rendezvous system with sensor faults, the specific steps are as follows:
[0037] Step 1: Establish a second-order fully actuated system model of the non-cooperative spacecraft rendezvous system
[0038] Considering the sensor fault δ(t), actuator saturation sat(u) and external disturbance d, establish a second-order fully actuated system model of the non-cooperative spacecraft rendezvous system:
[0039]
[0040]
[0041] where θ = [ρεβ] T is the system state vector, ρ represents the relative distance between the chaser spacecraft and the target spacecraft, ε and β respectively represent the pitch angle and yaw angle of the chaser spacecraft's tracking direction relative to the inertial coordinate system. u = [u1 u2 u3] T = [-a x -a y -a<L z T is the control input vector, a x , a y , a z respectively represent the accelerations of the chaser spacecraft in the X-axis, Y-axis and Z-axis directions. y is the measured output. μ = 3.986×10 14 m 3 / s 2 , is the gravitational constant. R ch = [R x R y R z T is the vector from the earth's center to the centroid of the chaser spacecraft. t represents time, u max and u min are respectively the maximum and minimum values of the control input, represent the first derivative and second derivative respectively, || || represents the 2-norm.
[0042] Define f = G -1 (θ)d, rewrite the above second-order fully actuated system model as:
[0043]
[0044] G -1 (θ) represents the inverse of the matrix G(θ).
[0045] Step 2: State observer design
[0046] Define Design the following state observer for estimating the system state vector θ and the external disturbance d:
[0047]
[0048] where, are the estimated values of Z1, Z2, and f respectively, is the observer parameter matrix to be designed.
[0049] Step 3: Design of the anti-saturation controller
[0050] Design the following sliding mode surface function s:
[0051]
[0052] where A0 and A1 are the parameter matrices to be designed.
[0053] Design an anti-saturation compensator with the following dynamic equation:
[0054]
[0055] where υ is the compensator state, is the input error, and γ, l1 are positive parameters.
[0056] Combine the sliding mode surface function and the anti-saturation compensator to design the anti-saturation controller u for the second-order fully actuated system model:
[0057]
[0058] where l2 is a positive parameter, and sgn(·) represents the sign function.
[0059] Step 4: Stability analysis of the closed-loop system
[0060] Define the state observer error variable e = [e1 e2 e3] T :
[0061]
[0062]
[0063] Select the following Lyapunov function:
[0064]
[0065] Taking the derivative with respect to time t gives:
[0066]
[0067] where, I represents the identity matrix.
[0068] When or V converges to a neighborhood of the origin, the closed-loop system is stable.
[0069] In this embodiment, at the initial time t = 0, the distance between the spacecraft and the earth's center is R ch =[7.4×10 6 m 7.4×10 6 m 3×10 6 m] T , the relative distance ρ(0)=400m, pitch angle ε(0)=30○, yaw angle β(0)=15○ between the chaser spacecraft and the target spacecraft, l1 = 1.5, l2 = 0.4, γ = 0.01, and the initial value of the anti-saturation compensator is υ(0)=[1 0.1 0.1] T , and solve the parameter matrix to be designed:
[0070]
[0071] Figure 1 , Figure 2 are the relative position and relative velocity between the two spacecraft in the non-cooperative spacecraft rendezvous system under the control of this method, respectively. It can be seen that the closed-loop system is stable, and after a period of time, the two spacecraft can successfully rendezvous. Figure 3 The control input curve of the system is shown. Saturation occurs briefly in the initial stage of the spacecraft operation. At this time, the anti-saturation compensator works to compensate for the performance loss caused by actuator saturation. After a period of time, the relative position, relative velocity, and control input converge to 0 under the adjustment of the controller, indicating that this method can effectively cope with the situation of actuator saturation. Moreover, the controller of this application uses the state value of the state observer instead of the sensor output value, making the controller immune to sensor failures.
Claims
1. Anti-saturation control method for non-cooperative spacecraft rendezvous system with sensor faults, characterized in that: The specific steps are as follows: Step 1: Considering the sensor fault δ(t), actuator saturation sat(u), and external disturbance d, establish a second-order fully actuated system model for the non-cooperative spacecraft rendezvous system; Step 2: Design a state observer to estimate the system state vector θ and the external disturbance d; Step 3: Design a sliding mode surface function s and an anti-saturation compensator, and design the controller u of the second-order fully actuated system model based on the observation values of the state observer; Step 4: Analyze the stability conditions of the closed-loop system, solve the parameter matrix to be designed, and obtain the anti-saturation controller u of the second-order fully actuated system model to achieve anti-saturation control of the non-cooperative spacecraft rendezvous system.
2. The anti-saturation control method for the non-cooperative spacecraft rendezvous system with sensor faults as described in claim 1, characterized in that: The second-order fully actuated system model of the non-cooperative spacecraft rendezvous system is: f = G -1 (θ)d where θ = [ρ ε β] T is the system state vector, ρ represents the relative distance between the tracking spacecraft and the target spacecraft, and ε and β represent the pitch angle and yaw angle of the tracking direction of the tracking spacecraft relative to the inertial coordinate system; u = [u1 u2 u3] T = [-a x -a y -a z T is the control input vector, a x , a y , a z respectively represent the accelerations of the tracking spacecraft in the X-axis, Y-axis, and Z-axis directions; y is the measurement output; μ is the gravitational constant, R ch = [R x R y R z T is the vector from the center of the earth to the center of mass of the tracking spacecraft; t represents time, u max and u min are the maximum and minimum values of the control input respectively, respectively represent the first derivative and the second derivative, || || represents the 2-norm; G -1 (θ) represents the inverse of the matrix G(θ). 3. The anti-saturation control method for the non-cooperative spacecraft rendezvous system with sensor faults as described in claim 2, characterized in that: The state observer is: Among them, are the estimated values of Z1, Z2, and f respectively, is the observer parameter matrix to be designed; The sliding mode surface function is: The dynamic equation of the anti-saturation compensator is: where, A0 and A1 are parameter matrices to be designed; υ is the compensator state, is the input error, and γ, l1 are positive parameters.
4. The anti-saturation control method for a non-cooperative spacecraft rendezvous system with sensor faults as described in claim 3, characterized in that: Set the parameters l1 = 1.5, γ = 0.
01.
5. The anti-saturation control method for a non-cooperative spacecraft rendezvous system with sensor faults as claimed in claim 3, wherein: The controller u is: Where, l2 is a positive parameter, and sgn(·) represents the sign function.
6. The anti-saturation control method for the non-cooperative spacecraft rendezvous system with sensor faults as described in claim 5, characterized in that: Set l2 = 0.
4.
7. The anti-saturation control method for the non-cooperative spacecraft rendezvous system with sensor faults according to claim 3, characterized in that: Select the Lyapunov function Analyze the stability conditions of the system and solve the parameter matrix to be designed 8. A computer-readable storage medium, on which a computer program is stored. When the computer program is executed on a computer, the computer is made to execute the method according to any one of claims 1 to 7.
9. A non-cooperative spacecraft rendezvous system, characterized in that: The tracking spacecraft conducts rendezvous with the non-cooperative target spacecraft according to the method according to any one of claims 1 to 7.