Design of First-Order Approximation Filters for Sliding-Mode Control of Uncertain Systems

The focus of this paper is on the synthesis of first-order filters which generate approximations for upper bounds of some signals needed in sliding mode control laws. The approximation is based on optimization methods which are applied to reduce the amplitude of the control signal. This paper also considers the application of these filters in output-feedback sliding mode controllers of linear systems in regular form with uncertain parameters and uncertain order. An experimental setup where the filters are applied to the model-reference control of an electromechanical system is presented to illustrate the design method.