Ride Control – A Two State Suspension Design for Cabs and Seats

Abstract

ABSTRACTThis paper presents a computer-controlled suspension design for tractors and semi-trailers cabs and driver's seats. Two separate models representing the vehicle with a cab suspension and the seat with an operator modeled as a lumped mass system are presented. The vehicle is represented by an 8 degrees-of-freedom (DOF) model, which includes a 3-axle tractor semi-trailer and a separated cab with suspensions. The seat/operator system is modeled by a 6 DOF model to simulate the vertical dynamic response of the driver including the seat suspension. The cab is supported by a set of controllable suspensions at both of the front and rear ends of the cab. The seat is attached to the floor of the cab by another controllable suspension. Each controllable suspension is modeled by a set of linear spring and non-linear damper whose coefficient is time dependent. First, a sky-hook based semi-active controller was designed to seek optimum cab suspension. Then, the second state controller was used with the cab's velocity and displacement as input to minimize the parameters of the seat/operator model. The seat suspension parameters were optimized to yield the best ride quality under the prescribed input road conditions. The ride comfort is measured using the absorbed power under stochastic road excitation.