Generalized discrete decoupling and control of MIMO systems

This paper proposes an efficient discrete‐time decoupling algorithm for multiple input multiple output (MIMO) systems having strong coupling between inputs and outputs. A design method for discrete decouplers is proposed to eliminate the cross‐coupling effects present in MIMO systems. The proposed decoupling technique is based on relative gain array (RGA) approach of MIMO system. In order to perform closed‐loop control, individual discrete‐time PID controllers are designed based on Kharitonov theorem for each of the SISO control loops of the resulting decoupled MIMO system. The closed‐loop performance of the MIMO system under consideration is investigated in simulation and in real time which illustrate that the proposed decoupling algorithm satisfactorily nullifies the interaction between the inputs and outputs. The control scheme exhibits perfect tracking of the reference commands even in presence of disturbances. Twin rotor MIMO system (TRMS) is considered as the real‐time example to validate the proposed method. Further, the performance of the compensated TRMS system is analyzed in frequency domain in presence of common actuator nonlinearities dead zone and saturation together. The performances of the controllers are found to be efficient even in presence of actuator nonlinearities.