Spacecraft Attitude Control Research Articles

Fault-tolerant control for the linearized spacecraft attitude control system with Markovian switching

In this article, the fault-tolerant control is investigated for the spacecraft attitude control system described by a linearized model with Markovian switching. First, the evolution of sudden failures of the spacecraft’s actuators is described by a Markov process. Then, the mathematical model of the spacecraft attitude control system with the Markov jump characteristic fault is established. Taking the uncertainty of the system model and external interference into consideration, a fault-tolerant control scheme is proposed for the established spacecraft attitude control system with the Markov jump characteristic fault by using the sliding mode control technique. Compared with some existing sliding mode controller design methods, the proposed method requires a less total number of LMIs to be solved. The stability and reachability of the resulting closed-loop system under the presented sliding mode control scheme are proven by applying the Lyapunov stability theory. Finally, some simulation results are provided to show the effectiveness and advantages of the proposed control method for spacecraft attitude control.

Model Predictive Control-Based Attitude Control of Under-Actuated Spacecraft Using Solar Radiation Pressure

An attitude control strategy for an under-actuated spacecraft with two reaction wheels is proposed, using the active assistance of solar radiation pressure torque. By changing the rotation angles of the solar panels, the magnitude and direction of the solar radiation pressure torque is assumed to be adjustable in this paper. The attitude dynamic model of a rigid spacecraft with two reaction wheels and two solar panels is established and transformed into the form of a non-linear system. An integrated control scheme based on dual-mode model predictive control is proposed, which obtains the rotation speeds of the solar panels and the rotation accelerations of the reaction wheels directly as control quantities. Using this control method, not only are the constraints of rotation speeds and rotation angles of the panels satisfied, but also the robustness of the closed-loop system is ensured. The simulation results prove the validity of the proposed control method.

Study on the coupled dynamics of rigid-liquid-flexible spacecraft by using isogeometric analysis for liquid sloshing

This paper focuses on the dynamics of a spacecraft coupled with propellant sloshing and flexible appendage vibration, which may lead to the inaccuracy and instability of the attitude control of spacecraft. The propellant sloshing is modeled and simulated by isogeometric analysis, combined with the level set method used for free surface tracking. A semi-slip boundary condition is proposed specifically for the numerical simulation procedure of liquid sloshing in a cylindrical tank. Based on the unique spatial mapping of isogeometric analysis, a method for evolving the level set function in the parameter domain of isogeometric analysis is presented. The vibration of a flexible solar panel is modeled based on the Kirchhoff–Love plate theory and the modal analysis method. The rigid-liquid-flexible coupled system of the spacecraft is divided into three modules coupled through interaction forces and torques. The effectiveness of the proposed modeling method for the rigid-liquid-flexible coupled spacecraft is verified by comparing with published experimental and analytical results. The simulation results show that due to the coupling effect, the small-amplitude liquid sloshing will cause a larger vibration of the flexible appendage, thus affecting the stability of spacecraft motion.

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.

Multiplicative fault concept and fault observer design for reliability study of degrading reaction wheel

The reaction wheel is a typical actuator and a crucial weak link in the spacecraft attitude control system, and much attention has been paid to its reliability problem. Due to limited samples and high cost for reaction wheel life tests, a simulation method by introducing attitude coupling dynamics and multiplicative fault concept is developed to analyze the logic of electric current as a performance indicator and verify its accuracy for reliability modeling. Furthermore, a new and intrinsic performance indicator of multiplicative fault is proposed for more application scenarios of reliability modeling and an adaptive sliding mode observer is designed for fault estimation. An illustrative example shows that the performance indicator of multiplicative fault can be used for various mission scenarios but requires certain persistent excitation, while electric current is the opposite.

Robust and fault-tolerant spacecraft attitude control based on an extended-observer design

The aim of this work is to develop a robust control strategy able to drive the attitude of a spacecraft to a reference value, despite the presence of unknown but bounded uncertainties in the system parameters and external disturbances. Thanks to the use of an extended observer design, the proposed control law is robust against all the uncertainties that affect the high-frequency gain matrix, which is shown to capture a broad spectrum of modelling issues, some of which are often neglected by traditional approaches. The proposed controller then provides robustness against parametric uncertainties, as moment of inertia estimation, payload deformations, actuator faults and external disturbances, while maintaining its asymptotic properties.

Hybrid nonfragile intermediate observer-based T-S fuzzy attitude control for flexible spacecraft with input saturation

This paper investigates a hybrid nonfragile intermediate observer-based T-S fuzzy attitude control strategy subject to multi-source complex disturbances to achieve integrated attitude stabilization and vibration suppression for the flexible spacecraft. A refined T-S fuzzy model for flexible spacecraft is introduced to represent the nonlinear characteristics in large-angle attitude maneuver. Then a hybrid nonfragile observer with coexisting additive and multiplicative perturbations is designed to estimate state information and disturbance simultaneously. Consequently, based on the closed-loop system, the quadratic stability and robust H∞ performance are proved via the Lyapunov stability analysis with corresponding conditions in terms of linear matrix inequalities (LMIs). It is worth mentioning that different from the limiter directly used in much literature, input saturation is disposed as a disturbance during the proof to satisfy the stability requirements. Finally, numerical simulations of a flexible spacecraft attitude control system are performed which demonstrate the effectiveness and superiority of the proposed control strategy.

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.

Constrained multi‐observer‐based fault‐tolerant disturbance‐rejection control for rigid spacecraft

AbstractThis article develops a multi‐observer‐based fault‐tolerant disturbance‐rejection control strategy to solve the attitude stabilization problem of spacecraft subject to multisource complex disturbances, for example, external disturbance, measurement error, actuator fault, input constraint. First, two intermediate variables are introduced for multi‐observer design, so that the synergistic estimations of attitude information, actuator fault and external disturbance are obtained simultaneously. Then, a fault‐tolerant disturbance‐rejection control strategy is proposed based on the estimations, and an augmented closed‐loop system is derived. Afterwards, Lyapunov stability analysis is performed to prove the quadratic stability and robust performance, and corresponding conditions in terms of linear matrix inequalities (LMIs) is proved, where the input constraint is satisfied as well. Finally, numerical simulations of a spacecraft attitude control system are performed which demonstrate the effectiveness and superiority of the proposed multi‐observer‐based control strategy.

Active fractional-order sliding mode control of flexible spacecraft under actuators saturation

In this article, a novel multi-objective modified fractional-order nonsingular terminal sliding mode (MFONTSM) controller is designed for the flexible spacecraft attitude control and passive vibration suppression, assuming the control torque saturation in the system dynamics. Then, by considering the effects of flexible components on the appendages modal equation as an external disturbance, an active FONTSM controller is designed separately to suppress any residual vibrations using piezoelectric actuators. The practical fixed-time stability of the closed-loop system is analyzed and proved using the Lyapunov theorem. Finally, the proposed controllers’ performance has been tested in the presence of uncertainties, external disturbances, and the absence of the damping matrix to study the proposed method’s effectiveness. It was observed that the proposed passive and active control strategies were able to achieve fast attitude stabilization while providing substantial vibration suppression under uncertainty and disturbance even in the absence of any damping terms in the system.

Attitude control of on-orbit capture spacecraft with angular velocity constraint

Aiming at the attitude control problem of spacecraft in the capturing non-cooperative target process, a dual tracking robust adaptive attitude controller is designed. Firstly, a bounded virtual angular velocity is designed for the kinematics equations to guarantee that the attitude converges to zero quickly. Secondly, a new attitude controller is constructed based on the barrier Lyapunov function to ensure that the tracking error between virtual angular velocity and real angular velocity is bounded. The physical constraint of the angular velocity is satisfied. Applying Lyapunov's stability theory, the global asymptotic stability of the closed-loop system is analyzed. To overcome the nonlinear parameter perturbation with unknown upper bound in the process of capturing non-cooperative target, an adaptive updating law based on linear regression operator is constructed to estimate the rotational inertia on-line. Finally, the process of capturing the trajectory tracking of non-cooperative targets through numerical simulation. The simulation results demonstrate that the algorithm designed is effective and robust under the constraint of the bounded angular velocity or internal parameter perturbation with unknown upper bound.

Prescribed Time Attitude Tracking Control of Spacecraft With Arbitrary Disturbance

The problem of developing a controller for spacecraft to accomplish attitude maneuvers within a prescribed time, independently of the initial states, is addressed. A fixed-time disturbance observer-based control is established and proved to drive the error state to zero, in a prescribed time, in the presence of modeling and external uncertainties. The key advantages of the proposed control are that the gains are explicitly determined by the prescribed maneuvering time only and that it is also robust to instantaneous disturbances. The control approach enables an efficient design process for attitude control applications with time constraints. Simulation results are presented for the attitude control of a rigid spacecraft to verify the benefits of this control scheme.

Observer-Based Fuzzy Sliding Mode Attitude Control for Flexible Spacecraft

In this paper, the attitude stabilization of flexible spacecraft with unmeasurable states and disturbances is addressed by an observer-based fuzzy integral sliding mode control scheme. First, a Takagi–Sugeno fuzzy model of flexible spacecraft is established and an observer is proposed based on this model. The convergence conditions of the estimation errors are given by Lyapunov function and the gains of the observer are thus determined. According to the obtained estimates, a novel fuzzy sliding mode control strategy is designed to compensate the influence of disturbance. Finally, an example of flexible spacecraft is employed to verify the effectiveness of the proposed observer and control law.

On the efficiency of using the Navier-Stokes approximation in thermogasdynamic calculation of low-thrust liquid-propellant rocket engines at low Reynolds numbers

A numerical method for thermogasdynamic calculation of low-thrust liquid rocket engines is presented. These engines are used as end organs of the system of space attitude control for nanosatellites and small spacecraft. The method is based on the use of the TERRA software package for thermodynamic calculation and the Ansys CFX software package for gas-dynamic calculation using the Navier-Stokes equations. The results of the thermogasdynamic calculation, as well as the flow pattern of the working fluid in the chamber, are presented. The results of validating the described method are also presented. Its capabilities and limitations are analyzed. The validation procedure is based on the comparison with the results of experimental data on the Reynolds number and the momentum thickness.

Spacecraft attitude control and vibration suppression using magnetically suspended control & sensitive gyroscope and radial basis function network adaptive sliding mode control

For the sake of improving the agility and super-static performance of spacecraft under external disturbances, this paper puts forward an idea for using pyramid configuration of the Magnetically Suspended Control & Sensitive Gyroscope to realize dual control of attitude maneuver and vibration suppression of spacecraft. The RBF neural network is used to reduce the chattering in sliding mode control through adaptively learning the non-linear part of the system. A band-pass filter is designed to divide the attitude deviation signal fed back by the sensors into high-frequency and low-frequency parts. The control laws of gyro gimbal and magnetic suspension rotor are designed, respectively, to realize the attitude maneuver and vibration suppression simultaneously. The adaptive laws of parameters avoid the saturation of rotor deflection angle while speeding up the attitude maneuver process of spacecraft. Compared with the traditional sliding mode control methods, the proposed one not only improves the accuracy and speed of attitude control but also improves the robustness of the spacecraft attitude control and vibration suppression system. Semi-physical simulation results show the effectiveness and superiority of the proposed method.

Neural network disturbance observer with extended weight matrix for spacecraft disturbance attenuation

A modified neural network-based disturbance observer with high-accuracy estimation performance is fabricated for spacecraft attitude control in this paper. To reduce the approximation error of the neural network with a limited number of neurons for complex disturbances, the weight matrix of the neural network is extended into a time series expansion and updated by a modified back propagation algorithm. Thus, the high-order dynamics of the weight matrix can be reconstructed, and the disturbance estimation accuracy is improved. Then, by introducing an integral state of the lumped disturbance into the disturbance model and utilizing it as the virtual disturbance measurement, an improved neural network-based disturbance observer is designed. The proposed observer takes advantages of the nonlinear approximation capability of the neural network and the high-order dynamics estimation ability of the extended observer structure. To realize high-performance attitude control of a spacecraft, a composite controller based on the proposed observer is designed, and then tested by comparative simulations. Simulation results show that, the estimation error of the designed observer can be reduced by an order of magnitude than the traditional observers. It is suitable for high-performance disturbance attenuation of verities of applications.

Finite-time active fault-tolerant attitude control for flexible spacecraft with vibration suppression and anti-unwinding

In this paper, a finite-time active fault-tolerant control scheme is designed for a flexible spacecraft’s attitude control experiencing inertial parametric variations, external disturbances, multiple actuator faults, and estimation errors while suppressing the flexible appendages’ vibrations without using smart vibration suppression actuators. First, relative attitude dynamics of a flexible spacecraft with multiple actuator faults are outlined, and a sliding mode observer is designed to estimate flexible appendages-related vibrations. The proposed fault detection and identification (FDI) strategy can efficiently detect actuator faults, avoiding the false alarms caused by uncertainties and disturbances, and accurately estimate the cumulative fault effects on the spacecraft via Chebyshev neural network (CNN) based estimator. Based on a novel fast nonsingular terminal sliding mode surface, a finite-time, unwinding-free, and adaptive fault-tolerant attitude controller is designed to acclimatize the detected faults and uncertainties effectively, also heeding the errors in the estimation of flexible modes and faults. The spacecraft can carry out the coveted control objective in a definable time, and the stability of the proposed controller is corroborated via Lyapunov techniques. Finally, a comparative simulation analysis with the existing results elucidated the proposed scheme’s efficacy.

Gimbal Angular Velocity Feedforward Method for Magnetically Suspended Control Moment Gyro with Hybrid Magnetic Bearing#

Control moment gyro(CMG) has the advantages of high precision and large output moment. It is the key actuator of agile spacecraft attitude control system. Magnetically suspended CMG(MSCMG) supports high-speed rotor through magnetic bearing, which has the advantages of no friction, no wear, high precision and long life. Hybrid magnetic bearing(HMB) generates bias magnetic field by replacing bias current with permanent magnet, which greatly reduces the power consumption. However, when MSCMG output moment, moving-gimbal effect makes the control current of HMB increase sharply, which result in the rapid increase of power consumption. To solve this problem, gimbal angular velocity feedforward(GAVF) method is proposed in this paper. Firstly, the model of HMB-rotor system containing moving-gimbal effect is established. Secondly, GAVF method is introduced to make the rotor deflect by designing a feedforward matrix with gimbal angular velocity and stiffness of HMB which is determined with rotor deflection angle and rotation speed. Thus, the gyroscopic moment is mainly offset by the bias magnetic field of HMB. Finally, an adaptive compensation method based on GAVF is proposed to maintain the system performance under parameter perturbation. By the above, the power consumption of control current during moment output process is reduced. Simulation and experiment results show the effectiveness of the proposed method.

Attitude Control of Spherical Liquid-Filled Spacecraft Based on High-Order Fully Actuated System Approaches

Attitude Control of Spherical Liquid-Filled Spacecraft Based on High-Order Fully Actuated System Approaches

Robust adaptive attitude control of flexible spacecraft using a sliding mode disturbance observer

A composite control scheme based on a disturbance observer is presented in this paper to deal with the attitude control problem of flexible spacecraft. Specifically, a sliding mode disturbance observer (SMDO) is developed to attenuate the unmodeled system dynamics, parameter uncertainties, and multiple external disturbances. The key feature of this approach is to relax the assumption imposed on disturbance to be constant or changing at a slow rate, which is a typical assumption in this class of problems involving a disturbance observer. Then, an exclusive adaptive integral sliding mode controller is combined with the SMDO to get the improved closed-loop control performance of the system. The underlying benefit of the proposed control scheme is improved robustness against time-dependent external disturbances and system model uncertainties. The stability analysis of the closed-loop system is provided using Lyapunov’s stability theory. Simulation results are provided to show the effectiveness of the proposed control scheme, especially in comparison with existing results.