Fault-Tolerant Control for Nonlinear Switched Systems with Unknown Control Coefficients and Full-State Constraints

2021 ◽  
Author(s):  
Yaxin Li ◽  
Libing Wu ◽  
Yuhan Hu
Keyword(s):  
Switched Systems ◽  
State Constraints ◽  
Fault Tolerant ◽  
Fault Tolerant Control ◽  
Nonlinear Switched Systems ◽  
Full State ◽  
Unknown Control Coefficients ◽  
Unknown Control ◽  
Full State Constraints ◽  
Control Coefficients

scholarly journals Adaptive tracking control for uncertain nonlinear systems subject to unknown control coefficients, state constraints, and input saturation

2021 ◽  
Author(s):  
Chunxiao Wang ◽  
Lu Qi ◽  
Yan Zhao ◽  
Jiali Yu
Keyword(s):  
Tracking Control ◽  
State Constraints ◽  
Input Saturation ◽  
Approximation Error ◽  
Tracking Performance ◽  
Dynamic Surface ◽  
Unknown Control Coefficients ◽  
Unknown Control ◽  
Control Direction ◽  
Control Coefficients

Abstract This article is committed to studying the tracking control problem for a class of uncertain nonlinear system with unknown control coefficients. The system is subject to full state constraints, input saturation constraint, and external disturbances simultaneously. By introducing a hyperbolic tangent function to approximate the saturated input function, the sharp corner caused by the input saturation is avoided. In the meanwhile, an auxiliary system is constructed to compensate the resulting approximation error. By using the barrier Lyapunov function (BLF) based adaptive backsteping control, the Nussbaum-type adaptive controllers are constructed for the augmented system with unknown control direction. It not only ensures the system states are always within the constrained range, but also guarantees the tracking performance of the system, no matter whether the control direction of the system is known or not. Meanwhile, dynamic surface control (DSC) is used in the controller design, which avoids ”computation explosion” caused by the repeated derivation of virtual control law. Aiming at the nonparametric uncertainty of the system, a common adaptive law is designed by combining the unknown constant bounds of the external disturbance with the error term caused by input saturation estimation. It improves the tracking performance of the system and reduces the burden of the controller greatly. Finally, a simulation example is given to demonstrate the effectiveness of the proposed control scheme in three scenarios.

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