聯結車在現今物流的過程中扮演著不可或缺的角色，然而質量大、重心高和機動性差等特性，使得事故發生率與致命性遠高於小型車輛，因此發展聯結車安全系統是勢在必行。為了能夠提升聯結車的側向穩定性，本研究發展一套車輛安全系統，藉由 LQR 控制半拖車(第三軸)轉向，以減少聯結車輛向後放大效應。本研究工作程序如下，首先選定聯結車線性模型作為設計 LQR 控制器之參照，並驗證聯結車線性模型的有效性，接著選擇適當的車輛期望狀態設計控制器，並進行道路情境的設計與模擬，最後將本研究所設計之控制器實際應用
於縮小型聯結車上。雖然模擬結果顯示所設計之控制器減少了聯結車的向後放大現象並成功防止車輛翻覆，但在實際實驗階段，由於實驗環境、感測器間的訊號干擾和車輛結構設計等原因，導致縮小型車輛無法順利的完成行駛情境並呈現向後放大效應。實驗最終，本研究改以觀察加入控制器後之車輛動態響應，結果表明，追蹤適當的期望第五輪角度可以改善聯結車第五輪的穩定性。

Articulated vehicles play an indispensable role in logistics nowadays. However, due to the characteristics of high weight, high center of gravity and poor maneuverability, the accident rate and fatality of articulated vehicles are much higher than those of cars. Therefore, it is necessary to develop safety systems for articulated vehicles. To improve the lateral stability of articulated vehicles, the active trailer steering (3rd axle) control strategies by LQR controller are developed to reduce the rearward amplification in this thesis. The working procedures of this thesis are as follows. First, select the linear model of articulated vehicle as the reference for the LQR controller design, and then verify the linear model of articulated vehicle. Second, select the appropriate desired vehicle states for controller design. Third, design road scenarios and complete simulations. Finally, implement the designed controller on a 1:10 scaled articulated vehicle. Although the simulation results show that the designed controller reduces the rearward amplification and prevents rollover as well, in the actual experimental case, due to the experimental environment, signal disturbance among sensors and unfavorable vehicle structure design, the scaled vehicle cannot successfully complete the expected road scenario to exhibit rearward amplification phenomenon. In the end of the experiment, the study changed to observe the vehicle dynamic response after adding the controller. The results show that tracking the proper desired fifth wheel angle can improve the fifth wheel stability of articulated vehicle.

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