Synthesis of decoupling controller for non-minimum phase plants of different pole numbers on RHP within uncertainties

This article mainly studies the decoupling controller design for non-minimum phase plants of different pole numbers on RHP within uncertainties. The normalised coprime factorisation is considered to achieve the robustness requirements. The pole-zero cancellations on RHP should be averted for the sake of robustness. For convenience, the H∞ sub-optimal controller is utilised to meet the robust criterion of the plant. Some necessary state space formulae are also provided to facilitate the synthesis of the decoupling controller. The configuration of the two-parameter compensation is employed. The Bezout identity makes the feedforward controller easy to determine. A brief algorithm is presented. In addition, the proposed synthesis is illustrated with a numerical example. The robust bounds of the feedback controller can be assessed for both the additive uncertainty and the coprime factor uncertainties. The result shows that the compensated system is decoupled and is guaranteed to be internally stable within the specified robust bound although the pole number varies on RHP.