SAMPLED-DATA SYSTEM WITH COMPUTATION TIME-DELAY - OPTIMAL W-SYNTHESISMETHOD

We treat the control problem for sampled data systems that accounts fo r the time delay in the computation of the control action. The problem is formulated entirely in the w domain, and the optimum design is sol ved using an alternative method called optimal W-synthesis method. The method has been applied to the benchmark problem of a two-mass-spring system. Design results obtained indicate that the presence of computa tion time delay not only reduces the relative stability and robustness but also degrades the design performance. Loss in gain and phase marg ins is significant if the time delay is not accounted for in the contr ol-law synthesis. Furthermore, control activity can be highly sensitiv e to the inherent time delay resulting in excessive change in the cont rol action that may eventually lead to control saturation in a real sy stem. It is found that, when the time delay is incorporated into the c ontrol-law synthesis, stability, robustness, and performance loss beca use of computation time delay can be reduced.