Satellite Attitude System Research Articles

PD adaptive controller method for a three-axis stabilized rigid satellite attitude system

This paper deals with the attitude tracking control problem of rigid satellite with uncertainties of disturbances. An adaptive proportional derivative controller (PD) is proposed to deal with the influence of external disturbance in the attitude controller. The uncertain disturbances can be estimated through an adaptive algorithm and can be compensated in the proposed controller. The tracking error and the closed-loop system stability are ensured based on the Lyapunov analysis. using the representation of the spacecraft dynamics especially the quaternion properties.Simulation results can clearly illustrate the feasibility, the effectiveness and the performance of the planned control strategies, which have been validated by the Monte Carlo method, the results can be extended to other adaptive attitude control laws.

Classical and intelligent methods in model extraction and stabilization of a dual-axis reaction wheel pendulum: A comparative study

Controlling underactuated open-loop unstable systems is challenging. In this study, first, both nonlinear and linear models of a dual-axis reaction wheel pendulum (DA-RWP) are extracted by employing Lagrangian equations which are based on energy methods. Then to control the system and stabilize the pendulum's angle in the upright position, fuzzy logic based controllers for both x − y directions are developed. To show the efficiency of the designed intelligent controller, comparisons are made with its classical optimal control counterparts. In our simulations, as proof of the reliability and robustness of the fuzzy controller, two scenarios including noise-disturbance-free and noisy-disturbed situations are considered. The comparisons made between the classical and fuzzy-based controllers reveal the superiority of the proposed fuzzy logic controller, in terms of time response. The simulation results of our experiments in terms of both mathematical modeling and control can be deployed as a baseline for robotics and aerospace studies as developing walking humanoid robots and satellite attitude systems, respectively.

Fuzzy adaptive observer‐based fault estimation design with adjustable parameter for satellite under unknown actuator faults and perturbations

This study considers the problem of fault estimation for rigid satellite in the presence of external disturbances, parameter perturbations, and actuator time-varying faults. Firstly, a Takagi-Sugeno (T-S) fuzzy model with interval matrix for satellite attitude system under large attitude angle scope is established, along with a detailed analysis of actuator faults in terms of additive and multiplicative descriptions. Then, a novel fuzzy adaptive observer with adjustable parameter is proposed to estimate both system states and actuator faults. The estimated errors are proved to be uniformly ultimately bounded, based on descriptor augmentation technique and Lyapunov stability theory. The proposed observer realizes a lower estimation performance index in terms of quantitative assessment compared to existing observer methods. Furthermore, an auxiliary optimization variable and the elimination method are applied to decrease the conservatism of the proposed design. And an intuitive quantitative performance index of fault estimation is introduced to obtain reliable evaluation and decision. Finally, numerical simulations and analyses of rigid satellite illustrate the effectiveness and benefit of the proposed strategy.

Robust free‐time‐stable fault tolerant control for rigid satellite attitude system with output constraint

ABSTRACTThis article investigates the robust fault tolerant control strategy for a rigid satellite attitude system with external disturbance and actuator fault while the predesigned output constraint is taken into consideration. Based on the interval observer technique, an identical faulty signal reconstruction is first realized by utilizing pure mathematical calculation. Then, to guarantee the desired output constraint, the proposed prescribed performance fault tolerant control framework is constructed with a novel error interval representation which not only reduces the computation burden but also simplifies the output constrained controller design. In addition, by comparing with the existing finite/fixed time control method, the setting time for this control strategy can be assigned freely. The stability of the whole method is guaranteed by Lyapunov method. Finally, simulation results including comparisons with existing work show the effectiveness and advantages of the proposed approach.

A Data Fusion Fault Diagnosis Method Based on LSTM and DWT for Satellite Reaction Flywheel

This paper presents a novel fault diagnosis method based on data fusion for a reaction flywheel of the satellite attitude system. Different from most traditional fault diagnosis techniques, the proposed solution simultaneously accomplishes fault detection and identification within parallel fusion blocks. The core of this method is independent fusion block, which uses a generalized ordered weighted average (GOWA) operator to complement the characteristics of output data from long short-term memory (LSTM) neural network and discrete wavelet transform (DWT) so as to enhance the reliability and rapidity of decision-making. Moreover, minibatch normalization is selected to address the problem of covariate shift, realize the adaptive processing of the dynamic information in the original data, and improve the convergence speed of the network. With the high-fidelity model of the reaction flywheel, three common faults are, respectively, injected to collect experimental data. Extensive experiment results show the efficacy of the proposed method and the excellent performance achieved by LSTM and DWT.

Design of High Pointing Accuracy NPSAT-1 Satellite Attitude Systems of Armature Controlled DC Motor with utilization for PD Controller

An Attitude control system plays the important role to maintain the satellite to desired attitude orientations. The intended application of NANO satellite in low earth orbits (LEO) helps find transient responses with and without controllers. LEO satellites typically orbit at an altitude ranging between160-2000 km. LEO satellites are widely used for remote sensing, navigation, and military surveillance applications. The Nano NPSAT-1 satellite attitude control systems (ACS) are described in this research work. The high pointing accuracy attitude estimation and feedback control systems are presented. The design specifications have been taken to meet the accuracy requirements (desired value ≤ 0.2 seconds) of Nano satellite attitude control. The feedback signal from on-board sensors compared with reference orbit trajectory and implementation of the Proportional Derivative (PD) controller is constructed. An algorithm of Nano satellite (NPSAT-1) attitude control is implemented using MATLAB Tools. In addition, the closed loop poles help find the gain of the system using Root Locus (RL) methods. The satellite control system is used to improve the transient response like overshoot and settling time of the system. Thus, the design of attitude control to improve the rise time, the settling time, the maximum overshoot, and no steady state error was carried out.

Integrated fault tolerant attitude control approach for satellite attitude system with sensor faults

SummaryIn this study, a novel integrated fault tolerant control (FTC) strategy is proposed for a rigid satellite attitude systems under the case of external disturbance, Lipschitz nonlinearity, and sensor faults. Different from the traditional adaptive fault estimation method, an augmented fault estimation observer is designed for the considered faulty satellite attitude system, which could be used for estimating both system state and sensor fault. A virtual observer is firstly introduced, and then, a real observer is derived as a result of the unmeasurable information to be used for the design of the virtual observer. On this basis, an integrated FTC approach is developed for the considered faulty satellite attitude system by combining backstepping control and fractional order nonsingular terminal sliding mode control techniques, such that the closed‐loop system not only has good robustness to external disturbance but also has better fault tolerance capability to unknown sensor fault. Finally, a simulation example is provided to demonstrate the feasibility and advantage of the proposed FTC scheme.

Intelligent Fuzzy PD+I Controller with Stabilizer for Nano Satellite Attitude Control System

This paper discusses the variation of proportional and derivative gains in a system under the control of PD+I controller that uses fuzzy inference method an effort is made to design the fuzzy proportional-derivative (PD) + I controller for a nonlinear the proposed fuzzy PD + I structure shows superior performance in the Nano-satellite attitude control system. Given that 2-input PD type controllers are commonly used to control Nano satellite attitude systems (Innovative Satellite InnoSAT), This paper analysis the performance of Fuzzy PD+I on satellite system. Fuzzy PD+I controller design can control Nano satellite attitude control system nicely and utilized the Fuzzy PD+I controller which optimize the stability of the Nano Satellite control system. In addition, the scheme is robust to variations in nonlinearities, as well as the steady-state gain of the plant. We illustrate the effectiveness of our scheme In MATLAB / SMULINK simulation environment.

Integrated Fault-Tolerant Stabilization Control for Satellite Attitude Systems with Actuator and Sensor Faults

In this paper, the problem of integrated fault-tolerant stabilization control is studied for the attitude systems of a rigid satellite with both actuator and sensor faults. Firstly, a virtual observer is designed for the faulty attitude systems of rigid satellite in order to estimate the unknown actuator and sensor faults. Because the virtual observer includes unmeasurable information of the attitude systems, the real observer is then presented. On this basis, an integral sliding-mode fault-tolerant stabilization control approach is proposed by using the estimated fault information, and it not only suppresses the disturbance with a disturbance attenuation level $$\gamma $$ , but also eliminates the effects of actuator and sensor faults. Finally, the effectiveness of the proposed fault-tolerant stabilization scheme is demonstrated in the attitude systems of a rigid satellite subject to the time-varying actuator and sensor faults.

Active Fault Tolerant Control Scheme for Satellite Attitude Systems: Multiple Actuator Faults Case

In this paper, an active fault tolerant control (FTC) design approach is proposed for the satellite attitude systems with exogenous disturbance and multiple actuator faults. Firstly, the nonlinear attitude system model of rigid satellite with multiple actuator faults is given. Next, an actuator fault diagnosis scheme, including a fault detection module and a fault estimation module, is given so as to detect the time of unknown actuator faults occurred and obtain their estimation values. Then, a terminal sliding mode-based fault tolerant attitude controller is designed using backstepping control technique, which guarantees that the closed-loop attitude systems of rigid satellite are asymptotically stable in the presence of multiple actuator faults. Numerical simulations illustrate the good performance of active FTC proposed in this study.

Active fault tolerant control scheme for satellite attitude system subject to actuator time‐varying faults

This study investigates the active fault tolerant control (FTC) problem for the attitude system of a rigid satellite, which is affected by parameter uncertainty, unknown exogenous disturbance and actuator time-varying faults. The upper bounds of the actuator time-varying fault and the generalised perturbation are unknown. A novel adaptive non-linear fault estimation observer is designed in order to obtain the estimated value of unknown time-varying faults. Then, an active fault tolerant attitude control approach is proposed under the framework of both backstepping control and adaptive control theory. Consequently, the Lyapunov theory is used to prove the robust asymptotic stability for the closed-loop attitude system of a faulty satellite under the proposed FTC scheme. Finally, simulation results on an in-orbit rigid satellite are provided to show the good fault tolerant performance, which validate the effectiveness and feasibility of the proposed scheme.

Evaluation of geomagnetic field models using magnetometer measurements for satellite attitude determination system at low earth orbits: Case studies

In this study, different geomagnetic field models are compared in order to study the errors resulting from the representation of magnetic fields that affect the satellite attitude system. For this purpose, we used magnetometer data from two Low Earth Orbit (LEO) spacecraft and the geomagnetic models IGRF-12 (Thébault et al., 2015) and T89 (Tsyganenko, 1989) models to study the differences between the magnetic field components, strength and the angle between the predicted and observed vector magnetic fields. The comparisons were made during geomagnetically active and quiet days to see the effects of the geomagnetic storms and sub-storms on the predicted and observed magnetic fields and angles. The angles, in turn, are used to estimate the spacecraft attitude and hence, the differences between model and observations as well as between two models become important to determine and reduce the errors associated with the models under different space environment conditions. We show that the models differ from the observations even during the geomagnetically quiet times but the associated errors during the geomagnetically active times increase. We find that the T89 model gives closer predictions to the observations, especially during active times and the errors are smaller compared to the IGRF-12 model. The magnitude of the error in the angle under both environmental conditions was found to be less than 1°. For the first time, the geomagnetic models were used to address the effects of the near Earth space environment on the satellite attitude.

Mixed H<sub>2</sub>/H<sub>∞</sub> Control Approach and its Application in Satellite Attitude Control System

In this paper, we address the mixed H2/H∞ control approach for linear time-invariant system based on linear matrix inequality (LMI). First, the problem to be solved is stated, and the satellite attitude dynamics is established and converted into a corresponding state space form. Then, the mixed H2/H∞ controller based on LMIs is designed in order to attain the state feedback gain matrix. To validate the efficiency and practicability of the proposed controller, simulation results based on satellite attitude system are presented, from which we can observe that under the condition of external disturbances, the system will be stable within 150s, and the maximum of control torque will be no more than 0.025Nm. Expanding the controller gain will affect the stabilizing process, but not the stabilization time, and it will increase the control input which will bring pressure to the actuator.

Adaptive Robust Control of Satellite Attitude System

This paper presents a new algorithm in adaptive robust control of satellite with parametric uncertainty as inertia components. The algorithm can be described as a combination between fuzzy logic controller and robust sliding mode controller. Adaptive fuzzy of robust sliding mode controller (AFRSMC) as an intelligent robust nonlinear control algorithm, is designed to control satellite attitude system with complicated structure of nonlinearity, actuator saturation and unknown parameters. This algorithm is generic for attitude control system whatever the parameters of the satellite. It generates a relation between states measurements and controller gains. This relation enables the controller to govern attitude system even for unknown inertia components or disturbances models without high deterioration in performance of the system.The performance of the control algorithm is measured by study of sensitivity analysis.

Tuning fuzzy Bang–bang relay controller for satellite attitude control system

Two level Bang–bang controllers are generally used in conjunction with the thrust reaction actuator for spacecraft/satellite attitude control. These controllers are fast acting and firing time dependent; full or no thrust-power to control the satellite attitude in minimum time. Conventional Bang–bang fuzzy controller requires soft fuzzy engine, and a hardware relay to accomplish Bang–bang control action. A new fuzzy Bang–bang relay controller (FBBRC) is introduced in this paper. The new controller is inherently sub-optimal due to its Bang–bang property. The controller has fuzzy decision making capability in its inputs and have two fixed levels Bang–bang output. Consequently, the tuning of FBBRC is restricted to inputs parameters only in comparison to standard fuzzy logic controller (FLC) where the output parameters can also be tuned. The stability of new controller stems from well established Bang–bang sliding mode control theory. The new fuzzy controller is simulated on a three-axis satellite attitude control model and comparison is made with standard fuzzy logic controller. The work presented here demonstrates that tuning only the input membership function is sufficient and simpler than tuning both input and output membership functions in the standard FLC. The controller is tuned on-line with gradient descent optimization method. The Inherent chattering associated with two-level Bang–bang controller produce undesirable low amplitude high frequency limit cycles. The chattering can be easily stopped in propose fuzzy Bang–bang relay controller, hence adding multi-functionality to its simple design. Simulation result shows that the new controller has faster response time and is capable of controlling the satellite attitude system under adverse initial conditions.

Direct-adaptive Fuzzy Predictive Control of Satellite Attitude

A multi-input multi-output direct-adaptive fuzzy predictive tracking control method for a satellite attitude system with parametric uncertainty and external disturbance is presented.First,a nonlinear generalized predictive controller is designed based on the satellite attitude model;then,a direct-adaptive fuzzy controller is constructed to approximate the unknown terms in the predictive control law caused by system model uncertainties.It is proved that the proposed controller can make satellite track the desired attitude trajectory and force the tracking error to converge to a small neighborhood of the origin.Simulation results show the effectiveness of the method.

Optimization of fuzzy controller for minimum time response

Minimum time control is desired for non-linear spacecraft–satellite attitude systems to save on-board thruster fuel. The regulatory time depends on the initial attitude of the satellite. Bang–bang control of satellite attitude can be accomplished with fuzzy logic controller using largest of Maxima defuzzification technique. In case of fuzzy controller, earlier studies show that minimum response time depends on the span of the fuzzy controller membership functions. This paper shows how the non-linear relation between the initial attitude of satellite and spans of the fuzzy controller membership functions are optimized to achieve minimum response time by using Nelder–Mead simplex search method. A practical demonstration of fuzzy bang–bang control is demonstrated here by controlling angular position of a single axis attitude application. The pneumatic rotary actuator is controlled in real-time using Matlab–Simulink xPC target environment.