八輪車輛穩態轉向行為分析

Abstract

本研究主要探討八輪車輛穩態轉向行為。首先藉由運動學以及牛頓力學，建立八輪車輛轉向模型的幾何關係式與力平衡方程式。此模型的方程式中，包含八個輪胎的獨立轉向角、側滑角、正向負載轉移以及使用重型車輛的輪胎轉向剛性式。藉此建立八輪車輛轉向模型後，由於本研究發展之數學模型難以求得解析解，故採用數值分析配合全域搜尋的方式，以力平衡方程式做為目標函數搜尋數值解。根據數值分析的結果，探討不同配重下八輪車輛穩態轉向的瞬心位置、輪胎側滑角、迴轉半徑、偏擺角速度、輪胎轉向力等車輛狀態參數變化。模型建立後，先進行八輪車輛不同配重下前雙軸轉向行為的分析。後加入之第三軸或第四軸轉向功能，並比較其與八輪車輛前雙軸穩態轉向行為之差異，用以評估八輪車輛加入多軸轉向之效益。亦可維持前雙軸轉向之轉向角設定，藉由調整第四軸輪胎之轉向角度，分析不同的轉向角度對車輛穩態過彎行為之影響。利用本研究發展的模型，可對八輪車輛的側滑現象、正向負載轉移、轉向力分配以及多軸轉向對車輛行為的影響能有更完整的了解。

The purpose of this study is to understand the steady turning behaviors of eight-wheeled vehicle. First, an eight-wheeled independent steering vehicle model has been developed, and its motion equations based on the geometry and force equilibrium of the vehicle are derived for the steady state analysis. This model has included eight independent steering angles, slip angles, load transfer, and the model of tire of heavy duty vehicles. Applying numerical method on the model, numerical solutions can be found. The solutions can be used to investigate the steady turn behaviors of eight-wheeled vehicles which can cornering by the two axes in the front. Then, the effects of three axes steering have been studied. In addition, with holding the steering angle of two axes in the front, the effect of fourth axes steering have also be investigated. By using this model, the slip angle, cornering force and load transfer of each tire can be thoroughly realized. Finally, according to the tire characteristic above, the steady turning behaviors of eight wheel vehicle can be described.