多轴车辆线控液压转向系统设计及转角控制

为减小多轴转向车辆货厢部位的第三轴转向轮转向磨损，要求该车轮与驾驶室部位的前转向轮转角关系满足阿克曼转向原理。针对某型号8×2四轴重型车辆，设计出一种第三轴线控液压转向系统，并建立其动力学模型，设计了基于指数趋近律的滑模控制器对第三轴转向轮转角进行控制，选取典型工况对所设计的控制器进行了仿真分析，并进行实车试验验证。研究结果表明：基于指数趋近律的滑模控制比基于比例切换函数的滑模控制及开环控制响应更快速、趋近目标值时间及超调持续时间更短、稳态差值更小；与采用机械液压转向系统相比，安装基于该控制器的线控液压转向系统不仅能显著提高第三轴轮胎的转向抗磨损性能，同时也改善了整车的转向性能。

Design and Steering Angle Control of Steering-by-Wire Hydraulic Systems for Multi-axle Vehicles

The angle of the third axle steering wheel under the cargo box and the front steering wheel under the cab of multi-axle vehicles were required to conform to Ackerman principle for reducing rear steering wheel wear. The steering-by-wire hydraulic system was designed and the dynamics model was established based on a certain 8×2 four-axle heavy truck for controlling the steering angle of the third axle steering wheel. The sliding mode controller based on the exponential approach law was simulated in the typical operating conditions, and vehicle experiments were carried out. The experimental results show that the sliding mode controller based on the exponential approach law has faster response, shorter approaching time and overshoot duration, and smaller steady-state difference, compared with the sliding mode controller based on the proportional switching function and open-loop controller. Installation of the steering-by-wire hydraulic system based on the controller may significantly improve the steering wear resistance of the third axle tire, and improve the steering performance of the vehicles, compared with the mechanical hydraulic steering systems.