Improving Noise Attenuation in Modified Filtered Smith Predictor

This article deals with experimental evaluation of filtered Smith-predictor-inspired constrained dead time compensator (DTC) in thermal process control. In the simplest case it may be based on the integral plus dead time plant model. This brings not only identification&tuning simplicity, but at the same time it may be considered as a test on robustness of the compensator. By design of the noise attenuation filters of the disturbance feedforward it may significantly improve noise attenuation. Quantitative and qualitative evaluation can be carried out by performance measures built on deviations of the input and output transient responses from their ideal shapes with a cost functions which combines the shape related deviations with integral of absolute error. Thereby, tuning of the possibly higher-order DTC seems to be simpler than in similar tasks using PID control. Its overall design is also more transparent and straightforward with respect to the control constraints, where the traditional filtered Smith predictor and PID control require some additional anti-windup measures.