On Uniqueness of Filippov’s Solutions for Non-Smooth Systems Having Multiple Discontinuity Surfaces With Applications to Control Engineering

The analysis of the uniqueness of Filippov’s solutions to non-smooth control systems is important before the solutions can be sought. Such an analysis is extremely challenging when the discontinuity surface is the intersecting discontinuity surfaces. The key step is to study the intersections of the convex sets from Filippov’s inclusions and the sets containing vectors tangent to the discontinuity surfaces. Due to the fact that all the elements of these sets are functions of the states and time and their numerical values can not be obtained before the uniqueness of the solution is analyzed, the determination of such intersections, symbolically, is extremely difficult. In this paper, we propose to firstly transform the control system to a new state space where the discontinuity surfaces can be written in special forms. Secondly, we expand the sets associated with Filippov’s inclusion such that the determinations of the intersections become feasible. Two examples of practical non-smooth control systems are presented to demonstrate the efficacy of the method.