拖拉机电液耦合转向试验平台设计与硬件在环试验

针对电液耦合转向方案转向特性尚不明晰、转向数据采集和记录困难等问题，提出一种硬件在环拖拉机电液耦合转向试验平台设计方案。平台参数设计过程主要考虑功率损耗，为了满足电液耦合转向系统的性能要求，进行精度设计与量程设计。通过总体参数设计，得到电动助力、液压助力和阻力加载系统的参数计算模型，并基于AMESim建立电液耦合转向系统的控制与机械模型仿真进行了参数优化。通过基于dSPACE以及PXI的硬件在环控制方案，进行了各类转向工况试验验证，验证结果表明：阻力加载模拟系统能根据不同的地面条件、行驶工况等参数实现动态加载，响应速度和控制精度均能实现田间阻力模拟要求；电液助力转向系统能够产生较好的平滑助力，具有良好的转向路感；控制系统能与各传感器硬件协同配合，使拖拉机电液耦合转向试验平台具有良好的响应特性，能够真实还原拖拉机转向过程。

Design of Hardware in Loop Tractor Electro-hydraulic Coupling Steering Test Platform

Due to low cost and high maneuverability and the reserve of original hydraulic system, the electric hydraulic coupling steering system is widely applied in tractor automated driving, but it is still unclear about the steering scheme characteristics which is existing in the process of the steering system. In the research process of the steering system, the technicians have some problems, such as the acquisition of experimental data subject to the current experimental conditions, the difficulty of the acquisition and recording of steering data, and the cost of manpower and material resources in the field debugging and installation of the tractor steering device. Based on this, a hardware in the loop of electric hydraulic coupling tractor steering test platform was designed. The design process of the platform parameters mainly considered the power loss, and in order to meet the performance requirements of the electro-hydraulic coupling steering system, the precision design and range design were carried out. Through the overall parameter design, the parameter calculation model of the electro-hydraulic booster and the resistance loading system was obtained, and the control and mechanical model simulation of the electro-hydraulic coupling steering system were established based on AMESim to optimize the parameters. The test platform can realize simulation of steering resistance moment under different soil conditions, automatic compensation control of active resetting torque of steering system and the response characteristic analysis and experimental verification of the electro-hydraulic coupling steering system of tractor and the automatic driving test, including path tracking. Through the hardware in-loop control scheme based on dSPACE and PXI, all kinds of steering condition tests were carried out. The results showed that the resistance loading simulation system can realize dynamic loading according to different driving conditions and other parameters, and the response speed and control accuracy can meet the requirements of field resistance simulation and electro-hydraulic power steering system can produce better smooth power with a good sense of steering. Furthormore, the control system can cooperate with each sensor hardware, so that the tractor electro-hydraulic coupling steering test platform had a good response characteristics, which can truly restore the tractor steering process, and provide a good reference for technical personnel.