Analysis of multi-rate discrete equivalent of continuous controller

The paper is concerned with the analysis of multi-rate controllers, which update the controller output faster than the measurement sampling frequency by a factor of N. The controlled system is continuous, and the discrete time controller is obtained as its zero order hold equivalent. After deriving a set of equations necessary for analysis and design of multi-rate systems, the open loop characteristics of the multi-rate controller and the closed loop characteristics are examined. Several physical meanings can be derived from the formulation of the multi-rate controller