四輪轉向車輛避障控制之實驗研究

Abstract

本論文為研究四輪轉向系統車輛控制。四輪轉向系統能夠使前輪與後輪獨立轉向，使車輛擁有更好的操控性與穩定性。本論文以單邊軌道車輛模型為基礎，考慮車輛在等速度時的轉向行為，並且忽略滾動與前後傾斜運動的影響。 為了簡化設計控制器的過程，在文中車輛的轉移函數解耦合為兩個單輸入單輸出系統，可各別操縱側向加速度與旋轉速度。換言之，控制器可命令前輪與後輪轉向以便於追縱期望的車輛操縱行為的側向加速度和旋轉速度。 在研究最後部份，四輪轉向系統車輛完成躲避障礙物實驗。實驗結果表示理論與實驗上的差異，並且可了解這台四輪轉向車的控制特性與效果。

This thesis investigates the four-wheel-steering (4WS) control system of a vehicle. Four-wheel-steering vehicles, which can control the front wheel steering angle and rear wheel angle independently, have been investigated based on the single track model. Assumptions of constant longitudinal velocities and negligible roll and pitch motions of the vehicle are commonly adopted to make the single track model linear and time-invariant. In order to simplify the controller design process, the transfer functions of the vehicle in the thesis is decoupled into two single-input single-output systems to handle the lateral acceleration and the yaw rate individually. On the other hand, the controller commands the front and rear steering angles such that the lateral acceleration and the yaw rate of the vehicle can follow reference trajectories, and consequently the desired vehicle handling behavior is achieved.