Control
Sevil M. Sadigh; Narges Talebi Motlagh; Hossein Behesgti; Sahand Moharrami; Moharram Shameli
Abstract
In this paper, an adaptive fault-tolerant control based on modified nonsingular fast terminal sliding mode control is developed for attitude tracking of a satellite with three magnetorquers and one reaction wheel. The proposed approach is designed to be robust in the presence of actuator faults, external ...
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In this paper, an adaptive fault-tolerant control based on modified nonsingular fast terminal sliding mode control is developed for attitude tracking of a satellite with three magnetorquers and one reaction wheel. The proposed approach is designed to be robust in the presence of actuator faults, external disturbances, and inertia uncertainties and preserve the acceptable performance of system. The adaptive law is designed to estimate the upper bound of uncertain expressions, increase the tracking accuracy, and improve the performance of system. This parameter with a coefficient of sliding surface variable are used in the reaching phase of control law to achieve the chattering-free phenomenon. Stability and finite-time convergence of attitude variables is proved by the extended Lyapunov condition. To increase the tracking accuracy and compensate the required torque, a reaction wheel is used as a redundancy. Also, for increasing the control accuracy, the dynamics of this actuator is considered as well as the constraints of magnetorquers and reaction wheel. The simulations are performed and compared with the similar control method under the mentioned conditions to evaluate the performance of the proposed method. The results show the finite-time convergence, increasing the tracking accuracy, smoothing of satellite attitude changes, and generating the chattering-free control signals.
Control
Ali Foroutan; alireza safa
Abstract
The gyroscope system is an attractive nonlinear system that is used in various industries such as the military, aerospace, navigation, etc. Considering the importance and applications of the non-linear system of the gyroscope, the design of the control system for the operation of the gyroscope system ...
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The gyroscope system is an attractive nonlinear system that is used in various industries such as the military, aerospace, navigation, etc. Considering the importance and applications of the non-linear system of the gyroscope, the design of the control system for the operation of the gyroscope system is indispensable. Most systems in the real world have nonlinear dynamics, and it is inevitable to avoid the destructive effects of noise and unpredictable external disturbances. Nonlinear uncertainties in gyroscope dynamics, noise, and unpredictable external disturbances are major challenges in controller design. The model-free control is developed for this system. Particularly, the sliding mode controller is widely used in the control of non-linear systems due to its robustness to system dynamic uncertainties and system disturbances. In this paper, the dynamic behavior of the nonlinear gyroscope system is analyzed then a sliding mode controller based on the neural network is used to control the gyroscope system. The stability of the nonlinear gyroscope system is proved using Lyapunov's theory. The nonlinear model of the gyroscope is simulated in Simulink MATLAB to investigate the behavior of the proposed control method and compare it with other controller's methods, so the efficiency of the proposed control method in the control of the nonlinear gyroscope system is investigated
