A Novel Nonsingular Fixed-Time Sliding Mode Control of Uncertain Euler-Lagrange Systems

This article deals with the problem of fixed-time tracking control for a class of uncertain Euler-Lagrange systems with modeling uncertainties, actuator faults, and external disturbances. First, a novel NFTSM variable is developed by introducing an arctan function. This sliding mode can not only eliminate singular values, but also ensure that settling time is irrelevant to the initial conditions of system states. Then, an ANFTSMC law is designed by combining NFTSM and adaptive techniques. The significant features of this approach are that the proposed controller is continuous and chattering free, and the fixed-time stability is ensured in the presence of uncertainties and actuator faults. Theoretical analysis shows that the proposed sliding mode surface and the errors can converge into a small neighborhood in the scheduled time. Finally, the superior of the developed control strategy is substantiated with comparisons of simulation results.