Overall Stability Analysis of Hydraulic Actuator´s Switching Contact Control Using the Concept of Lyapunov Exponents

Control law switching in a complete contact task control of hydraulic actuators results in a highly nonlinear nonsmooth system. Stability analysis of such a system using Lyapunov direct method involves restrictive modeling assumptions. This paper presents an alternative approach for stability analysis using the concept of Lyapunov exponents. Advantages and challenges of applying the method on a hydraulically actuated switching contact task control system are discussed in detail. Issues considered in the analysis include solution analysis of nonlinear and linearized systems, linearization of nonlinear equations at the instants of discontinuity, existence of Lyapunov exponents, and stability of numerical computations. Theoretical results are complemented with test experiments.