Vibration control of electrorheological seat suspension with human-body model using sliding mode control

This paper presents vibration control performance of a semi-active electrorheological (ER) seat suspension system using a robust sliding mode controller (SMC). A cylindrical type of ER seat damper is manufactured for a commercial vehicle seat suspension and its field-dependent damping force is experimentally evaluated. A vertical vibration model of human-body is then derived and integrated with the governing equations of the ER seat suspension system. The integrated seat-driver model featured by a high order degree-of-freedom (dof) is reduced through a balanced model reduction method. The SMC is then designed based on the reduced model and the state observer is formulated to estimate feedback states which cannot be directly measured from sensors. By imposing a semi-active actuating condition, the synthesized SMC is experimentally realized. In the experimental implementation, a driver directly sits on the controlled seat. Both vertical displacement and acceleration are measured at seat frame and driver's head, respectively. Control performances are evaluated under various road conditions and compared with those obtained from conventional passive seat suspension system.