| description abstract | A yaw plane model with limited roll-DOF of a five-axle tractor semitrailer is developed to study the open-loop directional dynamics of the vehicle. A driver model incorporating path preview, low and high frequency compensatory gains and time delays, and prediction of the vehicle state, is developed and integrated with the vehicle model. The coupled model is analyzed to investigate the vehicle design, which could be best adapted in view of the control limits of different driver, which are identified in terms of preview distance, reaction time and compensatory gain. A performance index based upon the vehicle path tracking, directional response characteristics and the driver’s steering effort is formulated and minimized using Gauss-Newton method to derive the desirable ranges of vehicle parameters, that could be adapted for drivers with varying skills. It is concluded that the adaptability and thus the directional performance of the vehicle can be enhanced through variations in the weights and dimensions, and compliant properties of the suspension, tire and the fifth wheel. The results of the study suggest that a driver with superior driving skill can easily adapt a vehicle with relatively large size, soft suspension and higher degree of oversteer. The results further show that the driver-adapted vehicle yields up to 33 percent reduction in the steering effort demand posed on the driver, while the roll angle and yaw rate response decrease by up to 40 percent. | |
