Design of Disturbance Observers for Multi-Input Multi-Output Systems

In this paper, the long-standing problem of designing disturbance observers for multi-input multi-output (MIMO) systems is solved. The disturbance observer presented here has a simple structure equivalent to that of the internal model control (IMC), thereby there is no need for the system inversion. Techniques to design the proposed disturbance observer are given. Furthermore, the design procedure is illustrated via examples for different MIMO systems.