Multirate-sampled digital feedback system design via a predictive control approach

Utilising a model-based predictive control methodology, the paper describes the synthesis of two-degrees-of-freedom digital controllers in which either the control or measured variable is relatively fast-sampled. In contrast with previous related contributions, which were predicated upon state-space representations and viewed the use of unconventional sampling strategies as a means of providing additional flexibility in pole-assignment, input-output models are employed exclusively and in this context multirate sampling is regarded as a prospective design or implementational aid. With respect to the latter consideration, it is demonstrated that the intrinsic low pass filtering nature of fast output signal-sampled predictive compensators significantly reduces the sensitivity of a digital feedback system to measurement noise