多軸車輛之轉向幾何對穩態轉向行為之影響及分析

Abstract

本研究旨在探討轉向幾何對多軸車輛穩態轉向行為之影響。首先以運動學與牛頓力學建立考慮正向負載轉移之三自由度多軸車輛穩態轉向模型，其中包含Magic Formula輪胎模型以及三自由度簡化懸吊模型，再以Newton-Raphson數值方法搜尋穩態力平衡方程組之數值解。比較二軸、三軸與四軸車輛在不同轉向幾何如阿克曼、平行及其它配置下之瞬心位置與側滑角分佈特性，並以前雙軸阿克曼轉向幾何為基準，探討多軸輔助轉向對四軸車輛穩態轉向行為之影響。藉由分析不同轉向幾何對車輛表現之效益，如輪胎磨耗量、磨耗均勻性與車輛操縱性等，歸納出在不同操作情境下之建議轉向模式，如第四軸阿克曼、內側單輪、外側單輪、平行輔助轉向等。利用本研究發展之模型與分析結果，可對多軸車輛於穩態轉向時之側滑現象與操縱性以及受轉向幾何配置之影響能夠有更完整的了解。

The purpose of this work is to study the effects of steering geometry on steady-state cornering behaviors of multi-axle vehicles. First, based on kinematics and Newtonian mechanics, 3-DOF steady-state cornering vehicle models are presented. The models include the 3-DOF simplified suspension model and Magic Formula tire model. Then, Newton-Raphson Method, a numerical method, is applied to find the numerical solutions of the simultaneous equations of motion. As one of the modeling results, distribution characteristics of instantaneous centers and slip angles of 2-, 3-, and 4-axle vehicles with various steering geometries, such as Ackermann, parallel, and so on, are discussed. Serving as the benchmark, steady-state cornering behaviors of double-axle Ackermann steering are compared with those of multi-axle auxiliary steering. By analyzing the effects of various steering geometries on vehicles’ cornering behaviors, such as the amount and uniformity of tire wear, and maneuverability, different steering modes are recommended according to driving conditions. Finally, with the developed models and analysis results of this work, the effects of steering geometry on steady-state cornering behaviors of multi-axle vehicles can be further understood.