Attitude Control Of Rigid Spacecraft Research Articles

Adaptive Reduced Attitude Control for Rigid Spacecraft With Elliptical Pointing Constraints

This article investigates the reduced attitude control problem of a rigid spacecraft subject to elliptical pointing constraints and parameter uncertainties. Specifically, a diffeomorphic projection is proposed to map the constraints from 2-sphere to elliptical 2-sphere while with the pointing direction preserved. Then, the constrained reduced attitude control problem is transformed into a conventional obstacle avoidance problem on the 2-dimensional (2-D) Euclidean space via the elliptical stereographic projection. Benefiting from properties of the diffeomorphism and Kodischek-Rimon navigation functions, a sufficient condition to exclude local minima is obtained. A constrained adaptive reduced attitude controller is further developed and it is shown that almost asymptotical stability of the resulting closed-loop system can be ensured in the sense of a measure zero set. Finally, numerical examples are furnished to illustrate the effectiveness of the proposed controller.

Immersion and invariance sliding mode control with time-delay estimation for rigid spacecraft with uncertainties and actuator faults

This paper investigates the attitude control of rigid spacecraft with uncertainties and actuator faults. An immersion and invariance sliding mode control with time-delay estimation (IISMCTDE) is proposed to cope with uncertainties, disturbances, and actuator faults. First, time-delay estimation is utilized to reconstruct the total disturbances including uncertainties, disturbances, and actuator faults. Then, based on the time-delay estimation, an immersion and invariance sliding mode control (IISMC) scheme is developed to achieve accurate attitude tracking from the reconstructed knowledge. The proposed IISMCTDE can not only achieve finite-time convergence but also be simple and easy to operate. Simulations are provided to demonstrate the effectiveness of the proposed approach.

Fixed-time fault-tolerant attitude control for rigid spacecraft with torque saturation

This paper investigates the fixed-time attitude control problem for spacecraft under input saturation, actuator faults, and system uncertainties. Three novel saturated fixed-time nonsingular terminal sliding mode surfaces (NTSMSs) are designed, which can keep the system states fixed-time stable after the establishment of their sliding manifolds. Two of them are time-varying and firstly designed. Each of the two NTSMSs has an adjustment parameter that is adjusted dynamically and used to handle saturation and cancel the attitude dynamics. According to other related predesigned parameters, a conservative lower bound of this parameter is obtained. A saturated control scheme is then designed in conjunction with a newly proposed saturated reaching law. A modification strategy is carried out to facilitate the engineering applications of our methods. The fixed-time stability of the closed-loop systems is validated by Lyapunov stable theory. Simulation results validate the effectiveness and superiority of the proposed control scheme.

Output feedback attitude control for rigid spacecraft under attitude constraints

<p style='text-indent:20px;'>An output feedback control law is proposed in this paper for spacecraft attitude reorientation task. Although attitude maneuver has been widely investigated and obtained significant results, it is still challenging when considering attitude pointing constraints and lacking the information of angular velocity. Firstly, potential function is introduced to tackle attitude pointing constraints. Then, by jointly designing sign function and potential function, the anti-unwinding performance can also be achieved. Furthermore, the relevant information of angular velocity is obtained by utilizing first-order passive filter with the attitude error quaternion. Moreover, by properly selecting candidate Lyapunov function, the feasibility of attitude constraints can be rigorously proved under the proposed control law, while the stability of the system can be guaranteed without signal of angular velocity and information of inertia matrix. A numerical example is carried out to demonstrate the effectiveness of the proposed method.</p>

Barrier function-based adaptive integral sliding mode finite-time attitude control for rigid spacecraft

This paper investigates the problem of attitude tracking control with predefined-time convergence for rigid spacecraft under external disturbances and inertia uncertainties. Firstly, the proposed nominal controller is designed to achieve attitude tracking control of the rigid spacecraft in the absence of disturbances and inertia uncertainties, and the convergence of the spacecraft attitude errors can be selected in advance. Then, the integral sliding mode combined with barrier function-based adaptive laws is proposed to reject the disturbances and inertia uncertainties, and at the same time, a barrier function-based adaptive method can also ensure the solutions of the rigid spacecraft system belonging to a stipulated vicinity of the intended variables starting from the initial moment and the uncertainties’ upper bound is not overestimated. Finally, a numerical simulation is provided to illustrate the efficiency of the proposed control protocol.

A novel learning observer-based fault-tolerant attitude control for rigid spacecraft

This paper investigates a learning observer-based fault-tolerant control strategy for a rigid spacecraft attitude system with external disturbance, parameter uncertainty and actuator faults. An adaptive learning observer design approach, which does not require the upper bound information of generalized perturbation, is proposed to estimate the attitude angular velocities and reconstruct actuator faults accurately and quickly. On this basis, a fault tolerant attitude tracking control scheme is developed for spacecraft attitude stabilization by combining the estimation value and backstepping control technique. The stability of the faulty attitude system under the designed fault-tolerant control method is analyzed using Lyapunov framework. Finally, simulations are given to show the effectiveness of the proposed method.

Anti-Unwinding Immersion and Invariance Adaptive Attitude Control of Rigid Spacecraft with Inertia Uncertainties

Anti-Unwinding Immersion and Invariance Adaptive Attitude Control of Rigid Spacecraft with Inertia Uncertainties

A Low-Complexity PD-Like Attitude Control for Spacecraft With Full-State Constraints

The problem of attitude control for rigid spacecraft under the attitude and angular velocity constraints is investigated in this study. Particularly, a simple structure constrained proportional-derivative (PD)-like control is proposed which contains two portions. The first portion is a conventional PD control to provide convergence of the system states; whereas the second portion provides the desired performance specifications such as convergence rate, overshoot and steady-state bound for attitude and rotation velocity to improve the attitude pointing accuracy and pointing stability. The distinctive property of the suggested constrained control method is to ensure the desired performance in transient and steady-state phases for all the system states. It also possesses much simpler structure compared to the existing constrained control techniques since it is based on a new methodology. The simulation results conducted on a rigid spacecraft verify the efficiency of the proposed approach.

Model-Free Attitude Control of Spacecraft Based on PID-Guide TD3 Algorithm

This paper is devoted to model-free attitude control of rigid spacecraft in the presence of control torque saturation and external disturbances. Specifically, a model-free deep reinforcement learning (DRL) controller is proposed, which can learn continuously according to the feedback of the environment and realize the high-precision attitude control of spacecraft without repeatedly adjusting the controller parameters. Considering the continuity of state space and action space, the Twin Delayed Deep Deterministic Policy Gradient (TD3) algorithm based on actor-critic architecture is adopted. Compared with the Deep Deterministic Policy Gradient (DDPG) algorithm, TD3 has better performance. TD3 obtains the optimal policy by interacting with the environment without using any prior knowledge, so the learning process is time-consuming. Aiming at this problem, the PID-Guide TD3 algorithm is proposed, which can speed up the training speed and improve the convergence precision of the TD3 algorithm. Aiming at the problem that reinforcement learning (RL) is difficult to deploy in the actual environment, the pretraining/fine-tuning method is proposed for deployment, which can not only save training time and computing resources but also achieve good results quickly. The experimental results show that DRL controller can realize high-precision attitude stabilization and attitude tracking control, with fast response speed and small overshoot. The proposed PID-Guide TD3 algorithm has faster training speed and higher stability than the TD3 algorithm.

Saturated Attitude Control for Rigid Spacecraft Under Attitude Constraints

This paper addresses the attitude-maneuver control problem for a rigid-body spacecraft in the presence of attitude-constrained zones as well as input saturation. More specifically, attitude-constrained zones are properly encoded, and an admissible artificial potential function (APF) is developed under the unit-quaternion representation. The elaborately designed APF ensures a unique minimum without requiring convexity of constrained zones, which yields a less stringent condition from previous approaches. Benefiting from the bounded property of the gradient of the proposed APF, a saturated controller is presented to render the almost uniformly ultimate boundedness of maneuver errors while complying with underlying maneuver constraints. The associated stability analysis of the closed-loop system is ensured by using the primal Lyapunov and the dual Lyapunov techniques. Numerical simulation tests are presented to assess the efficiency and demonstrate the advantages of the proposed control scheme.

Attitude control of rigid spacecraft with predefined-time stability

This paper investigates the attitude tracking problem of a rigid spacecraft using contemporary predefined-time stability theory. To this end, the relative attitude kinematic and dynamic models of a spacecraft are presented. Then, a sliding mode surface and predefined-time stability theory are applied to ensure that both the tracking errors of the attitude, expressed by the quaternion and the angular velocity, converge to zero within a prescribed time. Simulation results demonstrate the performance of the proposed scheme.

Quantized Attitude Control of Rigid Spacecraft without Unwinding

Advanced spacecrafts like fractionated spacecrafts are developed using independent modules that interact with each other through a wireless communication channel. The designing of an attitude controller of such spacecrafts requires to abide by the constraints on communication resources. Therefore, in this paper, a logarithmic quantizer is employed for the attitude regulation of rigid spacecraft under limited utilization of the wireless network. The given spacecraft has inertial uncertainties and external disturbances. Furthermore, the quaternion based kinematics attitude representation suffers from the problem of unwinding due to multiple equilibrium points. Thus, under the action of the proposed anti-unwinding controller, the closed-loop system states converge to the uniformly ultimate bounds while attenuating the lumped disturbances and avoiding the unwinding phenomenon. The simulation analysis and the comparative study with multiple initial conditions illustrate the superior performance of the proposed control technique.

Integrated fault estimation and fault tolerant attitude control for rigid spacecraft with multiple actuator faults and saturation

This study proposes an integrated fault estimation (FE) and fault-tolerant control design for a rigid spacecraft attitude system with inertia uncertainties, external disturbances, input saturation, and different type multiple actuator faults. A barrier function is first introduced to eliminate the effects of inertia uncertainties and disturbances in the design of the sliding mode FE observer. By using the non-singular fast terminal sliding mode control technology, a finite-time fault-tolerant attitude stabilisation controller and a finite-time fault-tolerant attitude tracking controller are designed to guarantee that the closed-loop attitude system has a good fault-tolerant performance under actuator faults. Furthermore, when considering actuator saturation, an auxiliary system is utilised to compensate for the saturation. The stability of the closed-loop system is analysed by Lyapunov theory. Finally, the effectiveness of the proposed control approach is demonstrated via simulation results.

Comment on “Fixed-Time Attitude Control for Rigid Spacecraft With Actuator Saturation and Faults”

Based on a new fixed-time sliding mode control, a finite-time control for attitude stabilization of a rigid spacecraft subject to external disturbance, actuator faults, and input saturation has been presented by Jiang et al. The main objective of this comment is to point out a mistake in a critical theorem by Jiang et al. , which resulted in the ineffectiveness of the proposed controller.

Adaptive NFTSM-Based Fault Tolerant Control for a Class of Nonlinear System With Actuator Fault and Saturation

In this paper, an adaptive fault-tolerant control (FTC) strategy is proposed for a class of nonlinear systems in the presence of actuator fault, actuator saturation, and unknown external disturbance. The mathematical model of a second-order nonlinear system with actuator fault is first given, and a fault estimation observer is designed to estimate the occurred time-varying actuator fault. On this basis, the adaptive FTC strategy is proposed using both nonsingular fast terminal sliding mode (NFTSM) and radial basis function neural networks (RBFNNs) techniques to compensate for the negative effects caused by time-varying actuator fault and external disturbance. Another adaptive FTC scheme is further presented under actuator saturation case, and the Lyapunov stability analysis demonstrates that the designed FTC approach could guarantee that the trajectory of sliding mode dynamics could converge to a small neighborhood of the origin within a finite time. Compared with some existing results, the FTC approach proposed in this paper has better fault acceptability. Finally, the proposed adaptive FTC approach is applied to the attitude control of rigid spacecraft, and the simulation results illustrate the advantages of the designed control scheme.

Finite-time attitude quantised control for rigid spacecraft

ABSTRACTThis paper investigates the quantised finite-time attitude control for rigid spacecraft in the presence of external disturbance. First, a novel quantiser is designed with the combination and improvement of the traditional hysteresis logarithmic quantiser and hysteresis uniform quantiser, so that the innovative quantiser in this paper has the advantages of both hysteresis and uniform quantisers in ensuring chattering free and acceptable quantisation errors for better transient and steady-state performances. Second, a finite-time controller is synthesised even under disturbances and quantisation errors, and the closed-loop system/state converges to the region near zero in finite time. Finally, the attitude stabilisation and attitude tracking simulation results for the rigid spacecraft are presented to illustrate the effectiveness and feasibility of the proposed control strategy.

Continuous Finite-Time Attitude Control for Rigid Spacecraft Based on Angular Velocity Observer

This paper addresses the problem of designing an angular velocity observer and an output feedback attitude controller with finite-time convergence and disturbances for spacecraft. First, two new concepts of finite-time stability are proposed and defined as the local fast-finite-time stability and the fast-finite-time uniformly ultimately boundness, which can be seen as the extensions of the traditional fast-finite-time stability. Then, based on these two concepts of stability, a fast-finite-time observer is designed to estimate the unknown angular velocity. Next, based on the estimation of the angular velocity, a nonsingular and continuous attitude control algorithm is proposed to achieve the finite-time stability or finite-time boundness. With consideration of the observation errors and disturbances in the closed-loop system, a rigorous analysis of the proposed strategy is provided through Lyapunov approach. It shows that the observation errors and the spacecraft attitude will converge to a region of zero in finite time. Numerical simulation studies are presented to illustrate the effectiveness of the proposed observer-based attitude control scheme.

Finite-time sliding mode attitude control for rigid spacecraft without angular velocity measurement

The continuous finite-time nonsingular terminal sliding mode (NTSM) attitude tracking control for rigid spacecraft is investigated. Firstly, a finite-time attitude controller combined with a new adaptive update law is designed. Different from existing controllers, the proposed controller is inherently continuous and the chattering is effectively reduced. Then, an adaptive model-free finite-time state observer (AMFFTSO) and an angular velocity calculation algorithm (AVCA) are developed to estimate the unknown angular velocity. The unique feature of the proposed method is that the finite-time estimation of angular velocity is achieved and no prior knowledge of quaternion derivative upper bound is needed. Next, based on the estimated angular velocity, a finite-time attitude controller with only attitude measurement is developed. Finally, some simulations are presented and the effectiveness of the proposed control scheme is illustrated.

Fixed-Time Attitude Control for Rigid Spacecraft With Actuator Saturation and Faults

This brief investigates the finite-time control problem associated with attitude stabilization of a rigid spacecraft subject to external disturbance, actuator faults, and input saturation. More specifically, a novel fixed-time sliding mode surface is developed, and the settling time of the defined surface is shown to be independent of the initial conditions of the system. Then, a finite-time controller is derived to guarantee that the closed-loop system is stable in the sense of the fixed-time concept. The actuator-magnitude constraints are rigorously enforced and the attitude of the rigid spacecraft converges to the equilibrium in a finite time even in the presence of external disturbances and actuator faults. Numerical simulations illustrate the spacecraft performance obtained using the proposed controller.

Finite-time output feedback attitude control for rigid spacecraft under control input saturation

In this paper, the problem of finite-time output feedback attitude control for rigid spacecraft subject to control input saturation is investigated. For the attitude stabilization, we propose a nonlinear finite-time observer using quaternion-based attitude representation. The estimated attitude of the observer always satisfies the unit norm constraint. The finite-time stability of the observer can be guaranteed by using homogeneous and Lyapunov methods. Furthermore, the effect of the external disturbance on the performance of the finite-time observer is analyzed. With the finite-time observer, we design an attitude stabilizing control law to guarantee that the attitude state of the spacecraft converges to the equilibrium point in finite time. We also discuss the finite-time attitude tracking control for spacecraft and propose a control scheme without requiring angular velocity measurements to guarantee that the desired attitude can be tracked in finite time. The main novelty of the control algorithms derived here lies in the fact that finite-time stability can be achieved even in the absence of angular velocity measurements as well as in the presence of constraints on control input magnitude. Numerical examples are presented to demonstrate the efficiency of the proposed control algorithms.