Robust MIMO Control for Interconnected DC Motors

The paper deals with the robust controller design using conventional approaches (Small Gain Theory, Equivalent Subsystems Method), and advanced robust genetic method for uncertain MIMO systems. Decentralised robust controllers designed using the Small Gain Theory (SGT) ensure robust stability for additive, input/output multiplicative uncertainties; the Equivalent Subsystems Method (ESM) guarantees the required performance in terms of phase margin and settling time for input/output multiplicative uncertainties. The genetic algorithm is based on optimisation procedure, where the cost function to be minimized comprises the closed-loop simulation of the controlled MIMO process and evaluation of a selected performance index. Using this approach, the PID controller parameters were optimised to obtain the required behaviour of the controller process. Practical implementation and comparison of the proposed methods are verified and tested on a real process - two interconnected DC motors with varying parameters.