Handling-Stability Oriented Parameter Optimization for a Tractor Semi-Trailer Vehicle

Tractor semi-trailer as a widely-used heavy duty freight vehicle has caused many fatal accidents every year and one of the main factors of which may relate to its relatively poor lateral dynamics performance compared to the passenger cars [1, 2, 3]. In this paper, attention is concentrated on the parametric design for a tractor semi-trailer by optimizing the configuration parameters aiming to comprehensively improve the lateral dynamics performance. According to the previous public reports, the performance measures such as Load Transfer Ratio (LTR), Static Rollover Threshold (SRT), Rearward Amplification Ratio (RAR) and Ratio of Yaw Rate (RYR) are very effective measures and often be used to evaluate the handling and stability performances for tractor-trailer vehicles. However, each of those measures only pays attention to a certain aspect of vehicle lateral dynamics which is closely related to vehicle configuration parameters. Especially, the load scenario in transport which often varies from one task to another can make the lateral dynamics change considerably. Therefore it is difficult for a vehicle to obtain a comprehensively satisfying handling-stability performance in a wide range of load scenarios. In this work, two relatively comprehensive measures which directly link with vehicle configuration parameters have been formulated based on multivariable linear regression (MVLR) method respectively corresponding to the body roll and yaw dynamics in order to facilitate the implementation of handling- stability oriented design method. As an example, an optimal design scheme based on Multi-Objective Linear Programming (MOLP) method is presented and a set of optimum parameters are obtained. The handling and stability performances after optimization have been compared with those before optimization by simulations in TruckSim.