The closed-loop transfer function of a plant controlled with a classical feedback controller, depends on the dynamics of the plant. Since most feedforward tracking controllers are designed based on this closed-loop transfer function, they are not robust against plant model uncertainties. Sliding-mode controllers have the property that when the system is on the switching line, the closed-loop behavior is independent of the plant dynamics. As a result, it can be expected that a feedforward control design based on this closed-loop behavior is robust against plant model uncertainties. This paper studies this feedforward robustness issue in detail and verifies the results on an experimental test setup: a stage driven by a linear motor. An integrated procedure is proposed in designing the closed-loop discrete-time sliding mode controller using the reaching law method.

Issue Section:
Technical Papers
Keywords:
variable structure systems, discrete time systems, tracking, robust control, feedback, feedforward, transfer functions, closed loop systems, eigenvalues and eigenfunctions, Discrete Sliding Mode Control, Reaching Law, Tracking Control, Feedforward Control, Robust Control
Topics:
Control equipment, Design, Feedforward control, Transfer functions, Feedback, Tracking control
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