A Supervised Switching Discrete-Time Control Scheme for LTI Continuous-Time Plants Incorporating FROH´ and Multirate Sampling with Stabilization of the Discrete Plant Zeros

A multimodel scheme with a discrete-time matching controller for linear time-invariant (LTI) continuous-time plant is presented. The scheme incorporates several discretization models running in parallel. Each of these models is calculated from a different combination of the correcting gain beta in a fractional order hold (FROH) and the set of gains to reconstruct the plant input under multirate sampling with fast input sampling. The discrete unstable zeros are avoided through an appropriate design of the multirate gains so that the reference model might be freely chosen with no zeros constrains and perfect matching is achieved at sampling instants. The response within the inter-sample interval obtained with the use of this multimodel scheme is improved compared to the use of a single model scheme by the appropriate online choice of the discrete-time model activated to parameterize the model matching controller. A tracking performance index is used to select the model with the best behavior in the inter-sample periods.