Decentralized PI Controller Design Based on Phase Margin Specifications

An effective method for design and tuning of decentralized PI controllers for stable multi-input, multi-output systems is presented in this brief. The direct Nyquist array is applied to shape the Gershgorin bands for each loop separately such that they pass through a specified point corresponding to phase margin specification that is used as a single tuning parameter. The procedure is applied on the control of a laboratory model of quadruple-tank system.