Some contributions to the design of dead-time compensators

The main inconvenience of time-delay systems is that the plant output is delayed with respect to the plant input. So, in order to monitor, control or evaluate its behavior current information is not available. Dead-time compensators, mainly designed to control delayed plants, are aimed to provide undelayed data from the plant. Obviously, there is always an error between the estimated data and the undelayed process variables. The estimator behavior depends on the plant characteristics: stable/unstable, minimum/non-minimum phase, single-input-single-output/multiple-input-multiple-output or uncertain. In this paper, several structures to predict and estimate undelayed variables from the linear plant are reviewed and its advantages and drawbacks are discussed. The estimation error is evaluated and some solutions are proposed.