CONTROL OF NONLINEAR-SYSTEMS USING TERMINAL SLIDING MODES

Many robotic systems would, in the future, be required to operate in e nvironments that are highly unstructured and active, i.e., possessing means of self-actuation. Although a significant volume of results exis t in model-based, robust and adaptive control literature, general issu es pertinent to the performance of such control systems remain unresol ved, e.g., feasibility of implementing high gain switches for control robustness. It is also pointed out that in certain applications, contr ol switching can be very detrimental to the overall system. The primar y focus of this paper is development of a new approach to control synt hesis for robust robot operations in unstructured environments. To enh ance control performance with full model information, we introduce the notion of terminal convergence, and develop control laws based upon a new class of sliding modes, denoted terminal sliders. We demonstrate that terminal sliders provide robustness to parametric uncertainty wit hout having to resort to high frequency control switching, as in the c ase of conventional sliders [2]. In addition, stability analysis that is conducted to demonstrate terminal slider approach results in improv ed control performance and allows for simple robust design of control parameters. Further, improved (guaranteed) precision of terminal slide rs is argued for through an analysis of steady state behavior.