Adaptive Asymptotic Fault Tolerant Tracking of Uncertain Nonlinear Systems with Unknown Control Directions

In the article, the issues of asymptotic adaptive tracking control for the uncertain nonlinear systems in the presence of actuator faults and unknown control directions are investigated. By using the properties of Nussbaum function and backstepping technique, the problems resulted from the unknown signs of the nonlinear control functions are circumvented successfully. Moreover, a new adaptive asymptotic tracking control method is presented with the fault tolerant control framework, which is capable of realizing zero-tracking performance. The stability of the controlled system is ensured through fractional Lyapunov stability analysis. Finally, the validity of the raised scheme is verified by a simulation example.