ROBUST CONTROL STRATEGY FOR A LINEAR TIME-INVARIANT MULTIVARIABLE SAMPLED-DATA SERVOMECHANISM PROBLEM.

A robust control strategy for a linear sampled-data control system such that the error is asymptotically zero not only at, but also between, the sampling instances, in spite of both continuous and discrete disturbances, is proposed. The control strategy consists of an analog servocompensator driving the process, a digital servocompensator driven by the tracking error and driving the analog servocompensator, and a digital stabilizing compensator regulating an overall augmented discrete system formed by the discretized process and both the digital and analog servocompensators. The tracking error is shown to be asymptotically zero at all times. The control input to the analog servocompensator is zero in the steady state.