基於積分線性二次調節器於四輪轉向車輛橫向操縱與穩定性控制

Abstract

本研究主要針對四輪轉向車輛的橫向操縱與穩定性控制進行開發，並基於積分線性二次調節器(LQR with Integral Action, LQRI)設計控制器，以提升橫擺角速度的追蹤性能，並有效限制車身側滑角。首先，上層控制器透過傳統零側滑角方法計算出前輪與後輪轉向角的比例關係，再藉由線性二自由度單軌模型設計LQRI控制器，以計算所需的額外後輪轉向角及橫擺力矩之參考命令。下層控制則透過阿克曼轉向幾何和四輪獨立煞車系統，將上層控制器的控制命令分配至各輪，其中煞車力分配考慮到輪胎摩擦圓的限制，以避免輪胎力飽和，從而防止輪胎鎖死。最後，在MATLAB/Simulink環境中建立本研究提出的控制策略，並結合CarSim車輛模擬軟體進行模型在環(Model-in-the-Loop, MiL)驗證。模擬結果顯示，本研究所開發的控制策略能夠在激烈操控下有效改善車輛的操控性及穩定性，且轉向角與煞車壓力的利用率較低，進而減少能量消耗。此外，在車輛穩態時，有效減少橫擺角速度的誤差。

This research focuses on the lateral control and stability of four-wheel steering (4WS) vehicles, developing a control strategy based on Linear Quadratic Regulator with Integral Action (LQRI) to enhance the tracking performance of yaw rate and effectively limit the vehicle's sideslip angle. Initially, the upper-level controller calculates the proportional relationship between front and rear wheel steering angles using traditional zero sideslip angle methods. Subsequently, employing a linear two-degree-of-freedom single-track model, the LQRI controller computes reference commands for additional rear wheel steering angle and yaw moment. The lower-level control utilizes Ackermann steering geometry and four-wheel independent brake system (4WIB) to distribute commands from the upper-level controller to each wheel, with brake force distribution considering tire friction circle limits to prevent tire saturation and locking. Finally, the proposed control strategy is implemented in MATLAB/Simulink and validated through Model-in-the-Loop (MiL) simulations using CarSim vehicle simulation software. Simulation results demonstrate that the developed control strategy effectively improves vehicle handling and stability under aggressive maneuvers, with lower utilization of steering angles and brake pressures, thereby reducing energy consumption. Additionally, it effectively reduces yaw rate error during steady-state conditions.