Unknown Nonaffine High-Order Fully Actuated Systems: Trajectory Tracking and Fault Tolerance

In this article, the nonaffine high-order fully actuated system (HOFAS) structure is established, and a tracking controller and a robust fault-tolerant stabilization controller for unknown fully actuated systems are proposed. Starting from the unknown nonaffine HOFAS model, a saturated controller dynamic equation based on extended state observer is yielded, which ensures the low-power characteristics of the controller. Both the observation error and tracking error are shown to converge eventually, and the upper error bound can be adjusted to a small neighborhood near zero. Furthermore, for unknown nonaffine HOFASs with multiplicative actuator and sensor faults, a robust fault-tolerant stabilization controller is presented to guarantee the ultimately uniformly bounded stability and the convergence to zero. The main results are proved theoretically and illustrated experimentally.