Advanced PID controllers in MIMO systems

This paper revisits the problem of decentralised control of Multiple Input Multiple Output (MIMO) systems. In industrial process control this problem is typically solved through the use of Proportional Integral and Derivative (PID) regulators that are used to close single loops, according to the implicit assumption that interactions between input and output variables can be neglected. However special care and conservatism are required for the choice of the regulator gains so that stability can be preserved also in the presence of the interactions. The decentralised MIMO control problem is solved here by extending the Variable Structure - Proportional Controller (VS-PI) proposed in to the MIMO case, and considering a priority-based approach for the sequential control of the single loops. In this paper the general idea is presented and preliminary simulation results including a robot control using brushless DC motor drives are included.