8x8四軸車輛之輔助轉向系統分析與設計

Abstract

常規的8x8四軸車輛車通常只配置了前二軸機械式轉向車輪機構，其結構雖簡易可靠，但缺點為最小轉向半徑過大，影響機動性；為了提高此種車輛之低速轉向性能，本研究提出一套創新之輔助轉向系統的設計驗證流程，研究裝置於四軸重型越野車輛上之輔助轉向系統，從基礎的理論模型建立、進而代入實際車輛物理參數及轉向連桿機構與轉向機畢特門臂幾何關係，構建穩態轉向力學模型。再以前二軸轉向實車行駛試驗，驗證模型之正確性，接著將模型加入輔助轉向功能後找出最佳之輔助轉向方式，驗證輔助轉向系統之效能。在車輛低速行駛的條件下，建立一時間與方向盤角度函式，將函式代入穩態轉向模型後輸出行駛軌跡，比較有無輔助轉向系統之行駛特性差異。驗證第四軸輔助轉向之效益後，設計可獨立調變車輪轉向角度之輔助轉幾構，採用左右車輪電液壓控制系統，實際安裝於實車上並行駛測試效能。在此加入了以實車電腦繪圖（CAD）模型建立以ADAMS軟體進行行駛軌跡模擬，透過實驗結果比對穩態轉向力學模型與CAD模型之軌跡，驗證數值合理性以及輔助轉向系統之效能探討。藉由建立不同的模型特性，可提供進一步之多軸車輛輔助轉向系統之發展與研究使用。

Conventional 8×8 four-axle vehicles usually have the front two-axis mechanical steering wheel mechanism. The structure is reliable, but the disadvantage is the minimum steering radius, which affects the mobility. In order to reduce the steering radius, this study proposes a design verification process for an innovative auxiliary steering system, and studies the auxiliary steering system installed on a 4-axles heavy vehicle. It is built from the basic theoretical model and then substituted into the actual vehicle physical parameters. The mechanism relationship and the steering road wheels is used to construct a steady-state steering mechanics model. The vehicle test drive was carried out to verify the correctness of the model. Then the model was added to the auxiliary steering function to find the best mode to verify the effectiveness. Under the low speed condition, a time and steering angle function is established, and the function is substituted into the steady-state steering model to output the driving track, and the difference in driving characteristics of the auxiliary steering system is compared. After verifying the benefits of the assisted steering, the design using electro-hydraulic control system, and actually installed on the vehicle and driving test performance. In this paper, the CAD model is used to establish the driving track simulation with ADAMS software. The tracks of the two models are compared through the experimental results to verify the numerical rationality and the effectiveness of the auxiliary steering system. Further development and research use of multi-axis vehicle-assisted steering systems can be provided by establishing different model characteristics.