Development of 2 DOF Truck's Suspension Seat for Improving Ride Comfort

Besides the driver and passenger's ride comfort, health harmfulness from oscillation motion must be taken into consideration, especially the drivers who work daily 9-hours long terms like in trucks. The unwanted vibration transmitted from unpredicted road roughness and some disturbance via the chassis and seat to human caused the injury. Generally the passive seats amplified vibration at low frequency between its resonance. For this reasons, we proposed and developed the active seat suspension to reduce the vertical acceleration. The problem was firstly identified via the vibration investigation and field measurement. We have also found that the seat pitch angle and pitch rate disturb the driver is aspect of ride comfort. The two degree of freedom driver seat model in vertical direction and pitch angle were demonstrated with assuming small displacement and pitch model. The equivalent spring stiffness and damping coefficient was preliminary estimated around the operation point. Due to the system nonlinearity between the operating ranges, the FLC was developed together with the optimal index, simulated via Matlab/Sumulink. The results figured out that the proposed controllers are effective in attenuating the vertical acceleration at driver seat. The weight root mean square vertical acceleration must follow the comfort range following ISO 2631-1 as well as the pitch rate amplitude were remarkably reduced.