An innovative two-layer multiple-DOF seat suspension for vehicle whole body vibration control

This paper proposes an innovative two-layer multiple degrees of freedom (multiple-DOF) seat suspension for reducing whole body vibration (WBV) of heavy duty vehicle drivers. This seat suspension is composed of a bottom-layer suspension for vertical vibration control and a top-layer suspension with two independently controlled rotational DOFs. The proposed seat suspension can reduce the vibration of driver body in five DOFs except the yaw vibration, which has least effect on human body, with only three actuators; though the five DOFs cannot be fully controlled by the three actuators, all of their magnitudes can be reduced. Another advantage of the proposed two-layer structure is that the vertical vibration reduction can be decoupled from reducing the lateral trunk bending and forward flexion of the driver body, according to the fact that the most sensitive frequency contents of the vertical vibration to human body are much higher than the frequency contents of other four DOFs vibrations. The top-layer suspension is tested; then its rotational stiffness and friction are identified. A decoupled model is derived and used in order to design a controller for the top-layer suspension. The experiments are implemented, where the random roll and pitch vibrations with random vertical vibration are exerted on the seat suspension base, respectively. The results indicate that, the interaction of the top-layer and the bottom-layer is small; with the proposed multiple-DOF seat suspension, the WBV in five DOFs can be reduced simultaneously. This multiple-DOF seat suspension is applicable for WBV control in heavy duty vehicles