Vehicle steering pull: from product development to manufacturing
The paper objective is to propose a novel method to evaluate the impact of dimensional variations on vehicle steering pull. Several attributes are important to increase the costumer perception of vehicle quality. Steering pull is one of these factors, which mean consistent pull to one side on a straight road while maintaining a constant speed, also called Vehicle Residual Aligning Torque (VRAT). Camber, caster, toe, and other factors affect VRAT. These factors are geometric characteristics defined on project phases influenced by dimensional variation from manufacturing and assembly process of underbody, suspension and tires. We developed a computer model to predict the dimensional variation of every geometric characteristic based on vehicle parts tolerances and evaluate the main contributors to variation of a common compact automotive vehicle with MacPherson frontal suspension and Twist Beam rear suspension. The computer model allow optimizing wheel alignment characteristics, determining characteristics to add on FMEA and evaluate the dimensional variation impact on the quality results of directional dynamic of the vehicle with this model. The proposed method combines Monte Carlo simulation to validate some the dimensional tolerances, a mutibody software to simulate initial data and a multi-objective optimization software to create a polynomial response surface and simulate the VRAT distribution curve, final directional vehicle trend and factors influence on VRAT. This method improved the time to complete the proposed simulation about 800 times compared to conventional simulation.