Development and applications of multirate digital control [25 Years Ago]

Multirate digital control is a significant area of current research and application that is motivated by practical implementation needs. The motivation for multirate control has traditionally been in aerospace applications where guidance and control laws must be designed to accommodate multiple rates of sensor measurements and finite throughput capabilities of onboard computers. Multirate design techniques should soon find further utility in control applications for highly distributed systems, such as communication networks, and power-plant/power-distribution networks where the characteristic frequencies and time-constants of a local station´s dynamics may differ significantly from those of the network as a whole. In this paper, the origins and evolution of multirate control techniques are summarized briefly, noting those contributions that have provided the basis for the more popular techniques now in use. This paper made a major contribution in showing the power and flexibility of state space techniques in characterizing many types of sampled data control systems, including time-varying systems.