A novel technique for the design of locally tuneable decentralised robust controllers

This paper proposes a decentralised controller design procedure for weakly coupled systems. A key feature of the design method is that the problem of designing a complete decentralised controller is replaced by several simpler local design problems. This is achieved by introducing a decomposition condition, which imposes local design constraints. This means that the design of each local controller is completely decoupled from other controllers. This has both design, and computational benefits. For the design, as long as each local controller satisfies the local decomposition condition, its design will be independent of the other controllers. In turn, this facilitates tuning and commissioning of the controller and the various design stages such as the choice of weighting functions. Most importantly this means that each of the loop-controllers is locally tunable. To achieve this, the decomposition condition is combined into a set of linear matrix inequalities (LMIs), then a sub-optimal robust solution for this type of control problem is obtained. The approach has been applied to several numerical examples and used for a case study of a gas turbine engine controller design. Copyright © 2009 SoftMotor Ltd.