Improved disturbance rejection for MIMO systems with output time delays

This paper presents a new control structure for improved rejection of unknown step disturbances in multiple-input, multiple-output systems with multiple time delays. After a review of published work extending the Smith Predictor for MIMO systems, the new control structure is presented using estimated and actual system outputs for output error prediction but using state-space control methods for the undelayed synthetic feedback loop. This new structure is applied to a simple example, demonstrating improved disturbance rejection (approximately half the integrated square error) and less sensitivity to mismatch in time delay estimates.