Purpose

The purpose of this study is to propose a torque vectoring control system for improving the handling stability of distributed drive electric buses under complicated driving conditions. Energy crisis and environment pollution are two key pressing issues faced by mankind. Pure electric buses are recognized as the effective method to solve the problems. Distributed drive electric buses (DDEBs) as an emerging mode of pure electric buses are attracting intense research interests around the world. Compared with the central driven electric buses, DDEB is able to control the driving and braking torque of each wheel individually and accurately to significantly enhance the handling stability. Therefore, the torque vectoring control (TVC) system is proposed to allocate the driving torque among four wheels reasonably to improve the handling stability of DDEBs.

Design/methodology/approach

The proposed TVC system is designed based on hierarchical control. The upper layer is direct yaw moment controller based on feedforward and feedback control. The feedforward control algorithm is designed to calculate the desired steady-state yaw moment based on the steering wheel angle and the longitudinal velocity. The feedback control is anti-windup sliding mode control algorithm, which takes the errors between actual and reference yaw rate as the control variables. The lower layer is torque allocation controller, including economical torque allocation control algorithm and optimal torque allocation control algorithm.

Findings

The steady static circular test has been carried out to demonstrate the effectiveness and control effort of the proposed TVC system. Compared with the field experiment results of tested bus with TVC system and without TVC system, the slip angle of tested bus with TVC system is much less than without TVC. And the actual yaw rate of tested bus with TVC system is able to track the reference yaw rate completely. The experiment results demonstrate that the TVC system has a remarkable performance in the real practice and improve the handling stability effectively.

Originality/value

In view of the large load transfer, the strong coupling characteristics of tire , the suspension and the steering system during coach corning, the vehicle reference steering characteristics is defined considering vehicle nonlinear characteristics and the feedforward term of torque vectoring control at different steering angles and speeds is designed. Meanwhile, in order to improve the robustness of controller, an anti-integral saturation sliding mode variable structure control algorithm is proposed as the feedback term of torque vectoring control.

中文翻译：

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复杂工况下分布式驱动电动客车转矩矢量控制系统

目的

本研究的目的是提出一种扭矩矢量控制系统，以提高分布式驱动电动客车在复杂驾驶条件下的操纵稳定性。能源危机和环境污染是人类面临的两大紧迫问题。纯电动公交车被公认为解决这些问题的有效方法。分布式驱动电动客车（DDEBs）作为一种新兴的纯电动客车模式，引起了世界各国的强烈研究兴趣。与中央驱动的电动客车相比，DDEB能够单独、准确地控制每个车轮的驱动和制动扭矩，显着提升操控稳定性。因此，提出了扭矩矢量控制（TVC）系统，以合理分配四个车轮之间的驱动扭矩，以提高DDEB的操纵稳定性。

设计/方法/方法

所提出的 TVC 系统是基于分层控制设计的。上层是基于前馈和反馈控制的直接横摆力矩控制器。前馈控制算法旨在根据方向盘角度和纵向速度计算所需的稳态横摆力矩。反馈控制为抗饱和滑模控制算法，以实际偏航角速度与参考偏航角速度之间的误差为控制变量。下层为转矩分配控制器，包括经济转矩分配控制算法和最优转矩分配控制算法。

发现

已经进行了稳态静态循环测试，以证明所提出的 TVC 系统的有效性和控制工作。与带TVC系统和不带TVC系统的被试客车的现场试验结果相比，带TVC系统的被试客车的侧偏角比不带TVC的客车要小很多。并且带有TVC系统的被测客车的实际横摆率能够完全跟踪参考横摆率。实验结果表明，TVC系统在实际使用中具有显着的性能，有效地提高了操纵稳定性。

原创性/价值

针对客车转弯过程中的大载荷传递、轮胎、悬架和转向系统的强耦合特性，考虑车辆非线性特性和不同转向角和速度下扭矩矢量控制的前馈项，定义了车辆参考转向特性。被设计。同时，为了提高控制器的鲁棒性，提出了一种抗积分饱和滑模变结构控制算法作为转矩矢量控制的反馈项。