Sliding mode observers for robust fault estimation in linear parameter varying systems

Abstract

A linear parameter varying sliding mode fault reconstruction scheme is proposed. Compared with other conventional sliding mode observer designs, the estimate emerges quite naturally from the equations governing the sliding motion, and although the process may be viewed as a filtering of the discontinuous injection, there is no phase lag introduced in the process. A semi-analytic solution to the proposed linear parameter varying sliding mode observer is first discussed. This motivates the structure of the linear matrix inequality formulation which is proposed, and clarifies the class of systems to which the approach is applicable. The linear matrix inequality problem set up minimises the induced L2 gain between the fault estimate and external disturbances, whilst ensuring linear quadratic performance of the underpinning sliding motion. The proposed scheme has been validated using the Japan Aerospace Exploration Agency’s Multi-Purpose Aviation Laboratory aircraft-in-the-loop platform to demonstrate the design efficacy.