实现多轴车辆纯滚动转向的新型变胞梯形驱动及多执行器电液伺服控制

Multi-axle vehicles with all-wheel pure rolling steering significantly enhance the maneuverability and handling stability, which becomes one of the important indicators to measure the development level of large-scale vehicles. Moreover, it has become the basis and forefront topic of academics and automotive engineering in the domestic and aboard. This research introduces metamorphic mechanism theory into the field of multi-axle steering, achieving the multi-axle vehicle with all-wheel pure rolling steering and precise electro-hydraulic servo control. Firstly, the new steering trapezoidal mechanism is designed and the impacts of the key parameters of metamorphic elements on the pure roll steering characteristics are studied. Secondly, the electro-hydraulic servo system based on metamorphic component and double steering cylinders is established, also the process of realizing the accurate pure rolling with 2 DOF is analyzed. Thirdly, the influence mechanism of key parameters of servo control on the dynamic steering characteristics is studied and the coupling laws of multiple actuators driven in the pure rolling constrain are revealed. Then, the combined numerical model considering the nonlinear characteristics are built and the optimization principles of the key parameters under the precise servo steering are studied. Finally, the coordinate control structure of pure rolling considering the multi-source drive coupling function is proposed and the adaptive robust control method facing precise pure roll turning is studied. This research provides a new approach and method for multi-axle vehicles to achieve accurate pure rolling steering, which plays an important role in the development of the basic science theory and key technology for multi-axle steering system.

多轴车辆全轮纯滚动转向可大幅提升车辆的机动灵活性和操纵稳定性，是衡量现代大型重载车辆发展水平的重要标志之一，已成为国内外学术界与工程界的基础前沿课题。本项目将变胞机构理论引入到多轴转向领域，开展多轴车辆的全轮纯滚动转向及其精确电液伺服控制研究：设计新型变胞转向梯形结构，研究变胞构件关键参数对纯滚动转向特性影响规律；建立基于变胞构件与双转向助力缸复合驱动的电液伺服转向系统，分析二自由度精确纯滚动转向实现过程；研究伺服控制关键参数对动态转向特性影响机理，揭示在纯滚动约束下多执行器驱动的耦合作用规律；建立考虑系统非线性特征的联合数值计算模型，研究精确伺服转向下的关键参数优选原则；提出考虑多源驱动力耦合作用的纯滚动转向协调控制结构，研究面向全路面的精确纯滚动转向自适应鲁棒控制方法。本项目研究为多轴车辆实现精确纯滚动转向提供了新途径与新方法，这对多轴转向基础科学理论与关键技术的发展有着重要意义。

多轴转向技术是决定重型多轴车辆操控稳定性和灵活性的关键技术，当前多轴转向无法实现全轮纯滚动转向，这使得轮胎在大角度转弯时出现磨损，同时严重影响整车的转向特性。本项目基于变胞机构理论，设计了一种横向拉杆可伸缩、锁紧的可变结构，使得转向系统可实现单/双自由度切换，既保证高速行驶的可靠性，又显著降低低速行驶时的轮胎磨损。通过梯形机构运动学及纯滚动转向约束分析，获取了全轮纯滚动阿克曼转角关系及其多模式转向约束条件；横向拉杆缸受力关键影响因素是系统泵源压力与两侧转向阻力矩，其呈现特殊受力规律即仅在单侧负载与转向趋于较大角度时出现受压状态，其余受拉；设计了新型变胞转向梯形机构及新型二自由度电液伺服转向系统，建造了一套用于重型车辆转向性能测试的试验台架，可实现转向系统伺服控制及载荷控制；建立了考虑单自由度工况的电液伺服转向系统数学模型，获取了关键参数对转向特性的影响规律，液压系统泄漏对数学模型在静止工况下液压缸两腔压力影响较大且不能忽略，否则易使控制器设计失效；建立了二自由度电液伺服转向系统数学模型和Matlab/Simulink仿真模型，分析了关键参数对转向特性的影响规律，二自由度转向下横向拉杆与转向机构产生耦合，使得横向拉杆缸极易发生抖振，可通过增大横向拉杆缸阻尼抑制抖振；以ITAE作为性能指标并结合惩罚函数并通过遗传算法整定PID参数，空载下电液伺服转向系统角度跟踪效果良好，但对负载扰动抑制较差；基于多项式拟合获得了用于非线性控制器设计的控制导向型模型，该模型具有较好拟合特性，基于此设计的积分滑模控制器可有效抑制负载扰动，跟踪效果良好；综合考虑系统模型存在未建模动态、参数不确定性，设计的自适应鲁棒控制也具有较好的电液伺服转向跟踪效果。通过项目的实施，目前已发表SCI期刊论文2篇，EI期刊论文1篇，申报发明专利4项，其中已授权2项。本项目的成果为多轴车辆全轮高精度动态转向系统设计与控制提供了新方法。