Reduced‐order non‐linear generalised minimum variance control for quasi‐linear parameter varying systems

Abstract

A reduced-order non-linear generalised minimum variance (NGMV) controller is introduced. The NGMV controller is one of the simplest control solutions for non-linear systems, with flexibility regarding the form of the non-linear system and the type of cost-function that may include non-linear elements. The new element is to introduce a pre-specified low-order controller structure. The motivation was the need to develop a non-linear industrial controller that has a simple structure and is easy to understand. The optimisation problem is to generate the optimal feedback controller gains or controller parameters on-line. These computations involve background processing to optimise gains or parameters. The gains vary as setpoints or disturbances change but for much of the time these are approximately constant. The approach provides a model-based optimal control solution, but in a form where classically trained engineers can easily retune if needed.