Two-degree-of-freedom controller design for MIMO systems with multiple time delays based on inversing decoupling

In this paper, a two-degree-of-freedom (TDOF) controller design method for multi-inputs multi-outputs (MIMO) system with multiple time delays based on inversing decoupling is proposed. Firstly, an inversing decoupling method based on the factorization of the plant is developed. Secondly, the H₂ optimal controller design method is applied to the decoupled single-input/single-output (SISO) system after the system has been decoupled. Finally, a TDOF controller is designed for the decoupled closed-loop system. Compared with other developed methods, the proposed design method has two main advantages. One is that the design procedure is simple and the obtained controllers are given in analytical form. The other is that better performance can be achieved since the TDOF control structure can isolate the disturbance from the reference. Simulations are provided to illustrate the effectiveness of the proposed design approach.