【作者】 王忠山；

【导师】 马文星；

【作者基本信息】 吉林大学 ， 机械设计及理论， 2022， 博士

【摘要】 丘陵山区耕地面积约占全国耕地总面积的70%,在我国农业发展中具有举足轻重的作用。山地丘陵的耕地由于田块小、不规则、坡地多,劳动强度大、劳动力短缺以及劳动力成本高等问题非常突出,研发针对丘陵地形的山地拖拉机,实施农业机械化是解决这一问题的重要途径。但由于丘陵地区特殊的地形和作业特点,农业机械必须具有良好的坡度自适应性,保证整车的作业平稳性与行驶安全。车身调平是一种能够根据丘陵作业地形的变化,自适应地将车身调平的核心技术,可以为拖拉机在丘陵地区作业时的安全性和平稳性提供坚实的技术保障。因此,本文基于国家重点研发计划“智能农机装备”专项,对车身调平机构及其控制系统原理进行了深入研究,研发了一整套适用于丘陵山地拖拉机工作要求的车身调平系统,主要研究工作和相关结论如下。1.基于丘陵山地拖拉机的整机特性要求,研究了丘陵山地拖拉机车身调平机理,确定了车身调平控制系统总体方案。设计了兼具车身调平、四轮驱动、四轮转向功能的前驱动桥与后驱动桥。研发了负载敏感车身调平液压系统与各功能阀块。依托整机指标要求、车身调平机构与车身调平液压系统,选择了自动调平型、手动调平型两种型号的车身调平控制器及其他关键元器件,开发了车身调平控制系统。2.对车身调平机构进行仿真模型建立与运动学分析,研究了姿态自调整转向驱动桥同时进行四轮转向、车身调平、动力传递时的运动学特性,解决了丘陵山地拖拉机的四轮转向、车身调平、传动驱动之间的匹配协调和运动干涉问题。研究了车身调平液压系统特性,验证了负载敏感液压系统的各项功能,选取了合适的液压系统的节流参数。3.采用四点调平原理进行丘陵山地拖拉机车身调平,给出了车身调平运动方程。提出了丘陵山地拖拉机车身姿态多传感器融合检测方法。通过编写合适的滤波程序,在不影响车身调平响应速度的前提下,解决丘陵山地拖拉机大负荷下发动机振动引起的传感器信号偏移问题,为控制系统的快速决策奠定了可靠的信号基础。4.针对丘陵山地拖拉机的几种典型作业工况,提出了不同的车身调平控制策略。基于不同的控制策略,开发了两种车身调平控制算法,分别对应高速响应调平与高精度调平。建立了丘陵山地拖拉机机电液联合仿真模型,采用两种控制算法进行分析,结果表明高速位置控制算法可以更快地响应路面变化,高精度位置控制算法具有更高的车身调平控制精度。5.考虑丘陵山地拖拉机使用需求与实际工况,开发了车身调平控制用户界面、控制指令及整机CAN总线通讯协议。基于通讯协议、控制指令以及车身调平控制算法,为车身调平控制器编写了车身姿态控制软件程序。6.为检验车身调平控制系统的各项性能,验证车身调平控制策略、控制算法的实际控制效果,分别进行了车身调平控制系统的台架试验与样机试验。台架试验验证了车身调平电液控制系统性能,对比分析液压系统仿真与台架试验结果,速度误差为0.55%、位移误差为0.02%。整机试验分别测试了车身调平控制算法在路面工况、耕作工况、转地块工况下的识别能力和控制精度。试验结果表明,在不同工况下车身调平控制系统工作良好、响应迅速,满足项目指标要求。更多还原

【Abstract】 Agriculture belongs to the Chinese largest industry,whose importance is selfevident.70% of China’s cultivated land belongs to hilly areas,and the degree of agricultural mechanization in hilly areas is still very low.The terrain in the hilly area is complex and the roads are winding and narrow.Therefore,traditional tractor operations in hilly areas face many problems,such as low safety,poor operation quality,difficult movement,and so on.To reduce the labor intensity of farmers,improve the level of agricultural mechanization in hilly areas,and ensure the operation safety of tractors in hilly areas and the quality of crop production,it is imperative to develop novel types of tractors with features of the stable body and flexible operation.Body leveling is crucial to the hilly mountain tractor,which can provide a solid technical guarantee for the safety and stability of the tractor when operating in hilly areas.Therefore,a complete set of body leveling systems suitable for the work requirements of the hilly mountain tractor is developed in the study.Furthermore,the body leveling mechanism and its control system are also studied in depth.The main research work and related findings are as follows.1.Based on the whole machine parameter requirements of the hilly mountain tractor,the body leveling mechanism of the hilly mountain tractor is studied,and the overall scheme of the body leveling control system is determined.The front-drive axle and rear-drive axle with the functions of body leveling,four-wheel drive,and fourwheel steering are designed.The load-sensitive body leveling hydraulic system and various functional valves are developed.Relying on the index requirements of the whole machine,the body leveling mechanism and body leveling hydraulic system,auto-leveling controller and manual leveling controller,and other key components are selected,and the body leveling control system is developed.2.The simulation model and kinematics analysis of the body leveling mechanism are established.The kinematics characteristics of the attitude self-adjusting steering drive axle during four-wheel steering,body leveling,and power transmission at the same time are studied.The problems of four-wheel steering,body leveling,matching coordination,and motion interference between transmission and drive of the hilly mountainous tractor are solved.The characteristics of the body leveling hydraulic system are studied,the functions of the load sensing hydraulic system are verified,and the appropriate throttling parameters of the hydraulic system are selected.3.The four-point leveling principle is used to level the tractor body in hilly and mountainous areas,and the body leveling motion equation is given.A multi-sensor fusion detection method for tractor body attitude in hilly and mountainous areas is proposed.By compiling an appropriate filtering program,on the premise of not affecting the response speed of body leveling,the problem of sensor signal offset caused by engine vibration of hilly and mountainous tractors under heavy load is solved,which lays a reliable signal foundation for the rapid decision-making of the control system.4.Aiming at several typical working conditions of tractors in hilly and mountainous areas,different body leveling control strategies are proposed.Based on different control strategies,two body leveling control algorithms are developed,which correspond to high-speed response leveling and high-precision leveling respectively.The hydro mechatronics co-simulation model of the hilly mountain tractor was established.,and two control algorithms are used for analysis.The results show that the high-speed position control algorithm can respond to the road changes faster,and the high-precision position control algorithm has higher body leveling control accuracy.5.Considering the use requirements and actual working conditions of the hilly mountain tractor,the user interface of body leveling control,control instruction and CAN bus communication protocol of the tractor was developed and designed.Based on the communication protocol,control instructions,and body leveling control algorithm,the tractor body attitude control software was developed for the body leveling controller.6.To test the performance of the body leveling control system and verify the actual control effect of the body leveling control algorithm,the bench test and the prototype test of the body leveling control were carried out respectively.The performance of the electrohydraulic control system for body leveling was verified by a bench test.The results show that the velocity error and displacement errors are 0.55% and 0.02%respectively.The whole machine test tested the ability of the machine body leveling control algorithm to identify operating conditions and its machine body leveling control accuracy under road conditions,farming conditions,and movement conditions.The test results show that the body leveling control system works well under different working conditions,and the accuracy of the hydro mechatronics co-simulation was verified through the analysis of the hydro mechatronics co-simulation and the comparison of the body attitude in the test process.更多还原