Continuous H [infinity symbol] and discrete time-varying finite horizon robust control with industrial applications

This thesis considers two areas of robust control. Part I considers continuous H control. The theory is applied to a scalar flexible transmission system that has non-minimum phase zeros and lightly damped modes that vary with applied load. A robust solution is obtained that gives good performance results. The capabilities of H techniques are more fully demonstrated on a research civil aircraft model (RCAM) flight control problem. A novel architecture for an autopilot to fly the RCAM along the final approach to landing is designed. Good results are obtained for the autopilot that incorporates controllers designed using both two degree-of-freedom H mixed sensitivity and H loop shaping techniques. In terms of a pre-defined mission scenario the overall results for performance, robustness, ride quality, safety and control effort are some of the best published, they demonstrate to the aerospace community the applicability and benefits of the methods.;Part II considers discrete time-varying finite horizon control. A number of new results in this area are presented, some being specialisations or extensions of existing finite horizon and time-invariant results, for example, means of computing the finite horizon norm and relationships between symplectic matrix equations and Riccati equations. Furthermore, normalised (coprime) factorisations and controller parameterisation results have enabled the optimum norm for the normalised left factored plant problem to be explicitly formulated. Formulae for a particular class of the problem are presented. A simplifying formula for the solution to the control Riccati equation of the problem is derived and a class of sub-optimal solutions, using non-zero terminal weights, is considered. The controller formulae are applied to a one-degree-of-freedom intercept problem with encouraging results. Robustness to relative lateral position errors and target acceleration perturbations are compared for the zero and non-zero terminal state weight cases.;.