基於滑模控制於四輪轉向車輛之橫向操縱與防側翻控制

Abstract

本研究針對四輪轉向車輛的橫向操縱與側傾穩定進行研究，並提出相應的控制策略。為提升行駛時的整體操縱性，本研究採用滑模控制（Sliding Mode Control, SMC）設計控制器，以強化車輛的操縱性能。而為了進一步優化車輛的側傾穩定性，利用翻覆指數（Roll Index）作為控制設計與穩定性評估之依據，並量化車輛於操控過程中的翻覆風險。在控制策略的設計上，首先由上層控制器計算車輛的翻覆指數，當翻覆指數超過所設定的安全目標值時，將使用以側傾穩定為主的控制策略；若翻覆指數在安全範圍內，則使用以操縱性能為主的控制器。下層控制的部分則結合阿克曼轉向幾何與四輪獨立煞車系統，將上層控制器輸出的指令分配至各車輪。煞車力分配過程中會考慮輪胎摩擦圓限制（Friction Circle Constraint），避免輪胎力飽和，從而防止輪胎鎖死，確保車輛在各種操控情境下的穩定與安全。 最後，本研究利用MATLAB/Simulink 建立控制策略，並用CarSim模擬軟體來驗證，綜合評估所設計控制器在提升車輛操縱與側傾穩定方面的成效。模擬結果顯示，所提出之控制方法能有效降低車身側傾與翻覆風險，同時維持良好的操縱表現，驗證本研究控制架構之可行性與實用性。

This study investigates the lateral handling and roll stability of four-wheel steering (4WS) vehicles and proposes a corresponding control strategy. To enhance overall handling performance during driving, a Sliding Mode Control (SMC) approach is adopted for controller design, aiming to improve vehicle maneuverability. Furthermore, a Rollover Index (RI) is utilized as both a control indicator and a stability assessment metric to quantify rollover risk during dynamic maneuvers. In terms of control architecture, the upper-level controller calculates the vehicle’s RI. When the RI exceeds a predefined safety threshold, a roll stability-oriented control strategy is activated; otherwise, a handling-oriented controller is employed. The lower-level control integrates Ackermann steering geometry and a four-wheel independent braking (4WIB) system to distribute control commands from the upper controller to each wheel. During the braking force allocation process, the tire friction circle constraint is considered to prevent force saturation and wheel lock-up, thereby ensuring vehicle stability and safety under various driving conditions. The proposed control strategy is implemented in MATLAB/Simulink and validated using CarSim simulation software. Simulation results demonstrate that the proposed method effectively reduces body roll and rollover risk while maintaining good handling performance, confirming the feasibility and practicality of the developed control framework.