Robust stabilisation of multivariable feedback systems with desired performance requirement

A design criterion is developed to achieve the following goals simultaneously: (i) input-output decoupling of multivariable feedback systems; (ii) complete and arbitrary closed-loop pole assignment; (iii) desired zero assignment for reference signal tracking; and (iv) robust stabilisation of multivariable feedback systems subjected to time-varying nonlinear uncertainties. Thus, the requirements of performance as well as stability robustness of a multivariable feedback system will be simultaneously met by employing this design criterion. Moreover, by minimising H∞-norm of each channel of the closed-loop transfer matrix, we can obtain the robustness optimisation of the system, i.e., we can predict the maximum slope of the sector-bounded nonlinear uncertainties that can be tolerated in each channel of the system. A practical example, the lateral flight control of CCV (control configured vehicle), is given to illustrate the validity of the proposed design algorithm.