Some issues on disturbance rejection for linear sampled data control systems

In the design of linear sampled data control systems, tradeoffs between achievable performance and disturbance rejection (sensitivity reduction) always manifest themselves. However, when disturbance rejection is considered to be the first priority, then question would be raised as how to design digital controllers to obtain asymptotic disturbance rejection in the first place. In this paper, a relation between loop shaping and internal model control for linear continuous/sampled-data systems is presented. The design criteria for achieving asymptotic disturbance rejection in linear sampled data control systems are also discussed