Performance of periodically time-varying controllers for sampled data control

Analyzes performance of periodically time-varying sampled data controllers for L/sub p/ deterministic and uniform disturbance rejection. For a given linear periodic sampled data controller controlling a linear time-invariant continuous-time plant, it is shown that a linear time-invariant controller can be found to give better L/sub p/ sampled data control than the time-varying controller. The performance analysis is in time domain using convexity properties of the L/sub p/ signal space.