Adaptive Fault-Tolerant Control of Uncertain Euler-Lagrange Systems With Time-Varying Actuator Faults

In this paper, the command tracking problem for uncertain Euler-Lagrange (EL) systems with multiple partial loss of effectiveness (PLOE) actuator faults is considered. Compared to the existing fault-tolerant controllers for Euler-Lagrange systems, the proposed adaptive controller accounts for parametric uncertainties in both the system parameters and multiple time-varying actuator fault parameters. The closed-loop fault-tolerant system is treated as a switched dynamical system, and a switched system stability is established using multiple Lyapunov functions. It is shown that all signals are bounded in each sub-interval and at the switching instances, and asymptotic tracking can be obtained for a finite number of fault occurrences. Finally, a simulation example on a robotic manipulator is presented to show the effectiveness of the proposed method.