Decentralized Hierarchical Multi-Rate Control of Constrained Linear Systems

This paper proposes a decentralized hierarchical multi-rate control scheme for large-scale dynamically-coupled linear systems subject to linear constraints on input and state variables. At the lower level, a set of decentralized and independent linear controllers stabilizes the process, without taking care of the constraints. Each controller receives reference signals from its own upper-level controller, that runs at a lower sampling frequency. By optimally constraining the magnitude and rate of variation of the reference signals to each lower-level controller, quantitative criteria are provided for selecting the ratio between the sampling rates of the upper and lower layers of control at each location, in a way that closed-loop stability is preserved and the fulfillment of the prescribed constraints is guaranteed.