The Split Control Method for MIMO Servo Design

A new servo design methodology for MIMO linear systems subject to unknown disturbances with output feedback which we the call `Split Control Method' is presented. In this method the control action is decomposed into two parts. One part is designed using Variable Structure Systems techniques and produces a rough motion around the desired state space trajectory. The other part is designed using the Model Based Compensator - Loop Transfer Recovery method, and acts as a fine tuner that brings the system output to the desired trajectory. Both designs are independent and stability of each design guarantees at least nominal stability of the combined system. Finally a switching disturbance is introduced to compensate for unknown external disturbances. For a nth order plant the resulting compensator is of order 2n. A 4th order, 2 input - 2 output example is shown. This servo design technique is restricted to minimum phase invertible plants and its extention to nonlinear systems is very promising.