Optimal Digital Control with Computation Time-Delay: a W-Synthesis Method

In this paper, we treat the control problem for sampled-data systems that accounts for time-delay in the computation of the control action. The problem is formualted entirely in the ¿-domain, and the optimum design is solved using an alternative method called Optimal W-Synthesis. The method has been applied to the benchmark problem of a two-mass-spring system. Design results obtained indicate that the presence of computation time-delay not only reduce the relative stability and robustness but also degrades the design performance. Loss in gain and phase margins is significant if the time-delay is not accounted for in the control-law synthesis. However, stability, robustness and performance can be recovered when computation time delay is included in the control-law synthesis.