Sample period effects in optimally designed digital control systems

A systematic procedure for obtaining an optimal sampled data control system which treats the sample period as a free design parameter is developed. The sensitivity of the closed-loop performance with respect to the sample period is examined for various choices of the penalty weighting factors and the compensator structure. An optimal nonzero sample period may exist, depending on the penalty weighting assigned to the system states even when a boundary condition is imposed that requires the optimal sampled data control system to converge to an optimal continuous control system as the sample period approaches zero.