Comparing Switching vs. Mixing MPC for Robust Fault-Tolerant Control

Abstract

We conduct a comparative study between two approaches for combining signals from several Model-Predictive Controllers (MPCs) designed for different fault scenarios. The first is MPC switching where a switch dictates which of the MPC controllers is currently active. The second is MPC mixing where all MPCs are running concurrently and their outputs are blended in proportion to the current estimate of fault state. We demonstrate results using a gravity drained multi-tank system. Our empirical results show that the mixing approach responds more quickly to faults than the switching approach. Further, we show that the speed and accuracy of fault isolation has a critical impact on fault tolerance.