A discrete robust adaptive control to stabilize LTI plants by using multirate sampling

This paper presents a strategy for designing a robust discrete-time adaptive controller for stabilizing continuous-time linear time invariant (LTI) plants. Such plants may be unstable and non-inversely stable. A reduced order plant model is considered to design the adaptive controller. The control design is based on the discretization of the plant with the use of a multirate sampling device with fast sampled input. A suitable online adaptation of the multirate gains guarantees the inverse stability of the discretized plant estimated model. A dead zone is included in the parameters estimation algorithm for robustness purposes under the presence of unmodeled dynamics.