Optimal decoupling for improved multivariable controller design, applied on an automotive vibration test rig

Within the framework of tracking controller design for an automotive vibration test rig, a new control strategy is developed which is applicable to square multiple-input-multiple-output systems (MIMO-systems) with a certain degree of symmetry. Classical MIMO-controller design is a three step procedure: response measurement, MIMO-identification and MIMO-controller design. The latter two steps are often very cumbersome due to the multivariable character of the problem. In. this paper, a new procedure is proposed which replaces the second step with: (1) almost decoupling of the MIMO-system into multiple single-input-single-output systems (SISO-systems) by transformations of the inputs and the outputs; and (2) SISO-identifications of the decoupled systems. Thereby simplifying the control-design step to multiple SISO-controller designs. This paper also discusses the successful application of this new procedure on an industrial automotive vibration test rig.