Modal space decoupling control for a hyper-redundant hydraulic shaking table

To solve the problem of coupling movements between degrees of freedom (DOF) of hyper-redundant shaking table while working with a load, a novel decoupling control strategy based on modal space is proposed. Linear model of hydraulic servo system is established and modal equation of hyper-redundant shaking table is given by considering hydraulic cylinder as a hydraulic spring. By standard modal matrix and its inverse matrix, the hyper-redundant shaking table is controlled in non-coupling modal space instead of DOF space. Three variables feedback control is employed in modal space to achieve decoupling control by pole placement. Simulation results show that the proposed decoupling control strategy can effectively improve tracking accuracy and reduce the dynamic coupling among DOF in both time and frequency domain.