Reduced-Order Compensator-Based Feedback Control of Large-Scale Systems

Chapter 5 continues to consider dynamical output feedback controller design. However, compared with Chapter 4, Chapter 5 focuses on large-scale interconnected systems and uses reduced-order compensators in the feedback loop which is particularly important for large scale systems to avoid ‘the curse of dimensionality’. Sliding mode dynamics are established and the stability is analysed using an equivalent control approach and a local coordinate transformation. A robust decentralised output feedback sliding mode control scheme is synthesized such that the interconnected system can be driven to the pre-designed sliding surface. This approach allows both the nominal isolated subsystem and the whole nominal system to be nonminimum phase. In a second approach, a similar structure is introduced to identify a class of nonlinear large-scale interconnected systems. By exploiting the system structure of similarity, the proposed nonlinear reduced-order control schemes allow more general forms of uncertainties. The study shows that similar structures can simplify the analysis and reduce computation. Case studies on the HIRM aircraft and coupled inverted pendula, and a numerical simulation example are provided respectively to illustrate the results developed.