Robust Control of Time Delay Systems

Abstract: This study presents the design of both H ∞ Loop Shaping Control (HLSC) and Internal Model Control (IMC) strategies for linear time delay systems. For first order time delay system, a systematic approach for weight selection based on the sensitivity function was proposed, then compared to the internal model control strategy. For both methods, the synthesis was based on the Pade approximation. Two cases are considered for time delay: upper or lower than system time constant. Simulation results for the proposed approaches are acceptable ever in presence of disturbances and model mismatches. Key words: H ∞ loop shaping control, internal model control, sensitivity function, constant delay, Pade approximation, model mismatches. 1. Introduction Robust control is a branch of control theory. It has been developed as a technique to make machine do what the model predicted. This theory deals with uncertainty in controller design. Robust methods are designed to achieve robust performance and/or stability in presence of bounded modeling errors. There are many techniques such as Adaptive Control, Fuzzy Control, Predictive Control, Internal Model Control, H