Safe Dual-Layer Nested Adaptive Prescribed Performance Control of Nonlinear Systems with Discontinuous Reference

Discontinuous reference signal is common in electromechanical systems, which can degrade control performances and raise system safety issues. To deal with these problems, this article proposes a safe dual-layer nested adaptive prescribed performance control approach for nonlinear systems, which ensures predefined transient and steady-state performances for the discontinuous reference signal. A monitoring mechanism is first established to detect discontinuous instants of the reference signal, and then the initial values of the prescribed performance boundaries are reformulated to cope with the discontinuities and maintain system stability. Different from the traditional prescribed performance control approaches, a novel dual-layer nested adaptive sliding mode compensation technique is introduced into the controller design to effectively handle system uncertainties without requiring prior upper bounds information. Simulation and experimental results on nonlinear servo systems are presented to validate the effectiveness of the proposed method.