Multiple Input Disturbance Decoupling: with Application to Vehicle Suspension Design

Control design for multivariable systems is challenging because all transmission paths are usually affected simultaneously. Therefore, disturbance response decoupling (DRD) was developed to keep specific transmission paths fixed while improving others. However, improving system responses simultaneously and independently has yet to be discussed. This paper proposes a novel control theorem called multiple input disturbance decoupling (MIDD) to answer this question. We first simplify the DRD theorem as the input disturbance decoupling (IDD) lemma, which allows independent modification of input responses. We then develop the MIDD theorem, where multiple IDD designs can be integrated to shape all input responses simultaneously as the individual IDD designs. Finally, we apply the MIDD control to a quarter-car model and demonstrate its effects.