Multirate sampling technique in digital control systems simulation

Digital regulators for continuous plants are designed today by means of conventional z-transfer function methods. With these z-transfer functions the value of the system output y(t) can be learned only at instants spaced T seconds apart, where T is the sampling period. A technique is proposed where the value of y(t) can be learned at instants spaced T/n seconds apart, where n is any integer. This technique is based on multirate sampling. First a method to calculate the output multirate sampled sequence is described. Then an efficient algorithm to calculate the multirate sampling discrete transfer function from the normal discrete transfer function is proposed.