scholarly journals Adaptive Integral-Type Terminal Sliding Mode Fault Tolerant Control for Spacecraft Attitude Tracking

IEEE Access ◽  
2019 ◽  
Vol 7 ◽  
pp. 35195-35207 ◽  
Author(s):  
Zhao Wang ◽  
Qi Li ◽  
Shurong Li
Keyword(s):  
Fault Tolerant ◽  
Sliding Mode ◽  
Fault Tolerant Control ◽  
Spacecraft Attitude ◽  
Integral Type ◽  
Terminal Sliding Mode ◽  
Attitude Tracking

scholarly journals Fault-tolerant control for a class of n-order systems based on fast terminal sliding mode and extended state observer

2021 ◽  
pp. 002029402110286
Author(s):  
Pu Yang ◽  
Peng Liu ◽  
ChenWan Wen ◽  
Huilin Geng
Keyword(s):  
Fault Tolerant ◽  
Sliding Mode ◽  
Singular Control ◽  
Fault Tolerant Control ◽  
State Observer ◽  
Extended State Observer ◽  
Extended State ◽  
Terminal Sliding Mode ◽  
Fast Terminal Sliding Mode ◽  
Terminal Sliding Surface

This paper focuses on fast terminal sliding mode fault-tolerant control for a class of n-order nonlinear systems. Firstly, when the actuator fault occurs, the extended state observer (ESO) is used to estimate the lumped uncertainty and its derivative of the system, so that the fault boundary is not needed to know. The convergence of ESO is proved theoretically. Secondly, a new type of fast terminal sliding surface is designed to achieve global fast convergence, non-singular control law and chattering reduction, and the Lyapunov stability criterion is used to prove that the system states converge to the origin of the sliding mode surface in finite time, which ensures the stability of the closed-loop system. Finally, the effectiveness and superiority of the proposed algorithm are verified by two simulation experiments of different order systems.

Fault tolerant control based on backstepping nonsingular terminal integral sliding mode and impedance control for a lower limb exoskeleton

2021 ◽  
pp. 095440622110357
Author(s):  
Majied Mokhtari ◽  
Mostafa Taghizadeh ◽  
Pegah Ghaf Ghanbari
Keyword(s):  
Sliding Mode Control ◽  
Lower Limb ◽  
Fault Tolerant ◽  
Sliding Mode ◽  
Impedance Control ◽  
Fault Tolerant Control ◽  
Integral Type ◽  
Lower Limb Exoskeleton ◽  
Mode Control ◽  
Control Scheme

In this paper, an active fault-tolerant control scheme is proposed for a lower limb exoskeleton, based on hybrid backstepping nonsingular fast terminal integral type sliding mode control and impedance control. To increase the robustness of the sliding mode controller and to eliminate the chattering, a nonsingular fast terminal integral type sliding surface is used, which ensures finite time convergence and high tracking accuracy. The backstepping term of this controller guarantees global stability based on Lyapunov stability criterion, and the impedance control reduces the interaction forces between the user and the robot. This controller employs a third order super twisting sliding mode observer for detecting, isolating ad estimating sensor and actuator faults. Motion stability based on zero moment point criterion is achieved by trajectory planning of waist joint. Furthermore, the highest level of stability, minimum error in tracking the desired joint trajectories, minimum interaction force between the user and the robot, and maximum system capability to handle the effect of faults are realized by optimizing the parameters of the desired trajectories, the controller and the observer, using harmony search algorithm. Simulation results for the proposed controller are compared with the results obtained from adaptive nonsingular fast terminal integral type sliding mode control, as well as conventional sliding mode control, which confirm the outperformance of the proposed control scheme.

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