【作者】 张小江；

【导师】 高秀华；

【作者基本信息】 吉林大学 ， 机械工程， 2011， 博士

【摘要】 论文是在吉林大学校企合作项目“全地面起重机行驶可靠性研究及设计参数化软件开发(A)”(项目编号：200822010100145)、“全地面起重机行驶可靠性研究及设计参数化软件开发(B)”(项目编号：2009220101001350)和江苏省科技成果转化专项基金“大型移动式起重机研发与产业化”(项目编号：BA2007038)的资助下开展的,随着我国乃至全球范围内在能源、交通及基础建设等大型工程项目的蓬勃发展,全地面起重机的市场需求急剧增长。多轴转向系统作为大型专用车辆、工程机械等重大技术装备的主要组成部分,对提升这些重大技术装备的自主创新能力,增强国家经济实力具有重要的战略意义。当前国内对大型全地面起重机理论平台的搭建刚刚起步；转向技术正从机械式液压助力转向转变为液压助力转向和电控相结合；对安全转向模式的控制研究尚在摸索；对大型全地面起重机操纵稳定性试验研究没有先例,致使我国大型全地面起重机整体行业发展滞后,因此研究多轴车辆转向技术,实现车辆安全、可靠转向显得尤为重要。论文在多轴转向车辆的操纵动力学模型、复杂系统虚拟样机仿真技术和试验研究、二次开发技术、多轴转向控制算法等几个方面进行了深入研究。数学模型是工程实践的关键核心技术,是多轴车辆转向研究的基础。本文建立了多轴转向车辆线性二自由度模型和线性三自由度模型,推导了在满足阿克曼定律的条件下前轮转角到横摆角速度、质心侧偏角和车身侧倾角的传递函数以及这三者的稳态增益表达式,并得到车辆的稳定性系数表达式,得到了影响车辆转向稳定性的因素。分析了在零侧偏角控制策略的条件下,车辆的质心和转向中心在车身上投影距离的关系式。分别分析了在低速、高速条件下,前轮转向车辆、全轮转向车辆和电控转向对车辆的转向性能的影响。在线性三自由度操纵动力学模型的基础上,建立了非线性三自由度模型,重点考虑轮胎侧偏刚度的非线性对车辆转向性能的影响,并进行了实例分析。原地转向时轮胎与地面的摩擦阻力矩一般为行驶转向时的2-3倍。轮胎原地转向特性对转向系统设计匹配至关重要。针对原地转向阻力矩经验公式不能描述转向阻力矩和轮胎转角之间关系这一问题,对轮胎原地转向阻力矩进行了实车测试,并将“魔术公式”和Lugre模型引入原地转向阻力矩的分析中,得到了很好的一致性。试验和分析表明：轮胎原地转向阻力矩和车轮转角呈非线性关系,阻力矩随着车轮转角的增加逐渐增大,最终趋于一个定值。针对全地面起重机在使用过程中出现部分转向杆件、转向横拉杆断裂和弯曲这一问题,对某七轴全地面起重机进行了原地转向实车测试和虚拟样机仿真,仿真结果和试验结果较为一致,找出了杆件受力的变化趋势。在不改变转向杆系参数保证车轮满足阿克曼定律的前提下,对转向油缸的尺寸和定位参数进行了优化设计,明显减低了转向杆系和转向横拉杆的受力状况,提高了转向杆系和转向横拉杆的可靠性。此种设计方法已被企业采用并成功的应用于其它起重机产品设计中。液压助力转向系统是全地面起重机转向系统的重要组成部分。根据限流阀、选择阀和转向器的实际结构,建立了各自的虚拟样机仿真模型,分析了各自的性能,并进行了台架试验测试验证。在此基础上,建立了转向系统机液-体化虚拟样机仿真模型,并进行了原地转向实车测试,通过试验结果的验证,确定全地面起重机液压助力转向系统虚拟样机模型的正确性。针对车辆原地转向和行驶转向所需的液压系统压力不同,当车轮转到“限位”位置时出现液压系统压力剧增、杆系受力发生突变这一问题,对液压助力转向系统进行了改进,并设计了相应的控制系统。本文针对全地面起重机车辆的特点,利用AMESIM开发了液压助力转向系统的液压元件库,利用ADAMS开发了机械系统参数化建模和优化程序,在此基础上利用Visual Basic语言开发了全地面起重机转向系统设计仿真分析平台。大大提高了设计的效率和精度,提高了产品的可靠性。目前此设计仿真平台已被企业采用,并成功的应用到相应的产品的开发和分析中。目前由于国内对大型多轴转向车辆的操纵稳定性的研究刚刚开始,整车试验研究还没有先例。本文在国内率先进行了全地面起重机的操纵稳定性进行整车试验,对某六轴全地面起重机进行了蛇行试验和稳态回转整车测试。并对该车进行虚拟样机仿真分析。为多轴转向车辆操纵稳性研究提供一定的参考依据。为了减低多轴车辆轮胎磨损,对多轴转向车辆操纵模型进行了改进,通过对多轴车辆的任意两个车轴车轮的转角控制就可以控制其它车轴车轮的转角,把多轴转向车辆和两轴车辆操纵模型统一起来。两轴转向车辆的有些转向控制算法可以用于多轴车辆,提高了有些控制算法的通用性。对机械转向车辆引入横摆力矩控制方法,以改善包括机械转向车辆的转向性能。利用无静差跟踪控制理论,设计了三自由度多轴转向车辆的跟踪控制器,分析对比了该控制器对全地面起重机转向性能的影响。仿真结果表明,使用无静差跟踪控制器的全地面起重机具有很好的跟踪性能,可以根据实际需要来提高车辆的转向性能,保证了全地面起重机的安全性和操纵稳定性。本文采用虚拟仿真分析和实车试验相结合的研究方法,深入研究了液压助力转向系统、复杂机械系统在转向过程中的性能。实现理论分析与试验相互验证、相互促进,为多轴转向车辆的设计提供了理论支撑,为多轴转向车辆操纵稳定性研究提供了一定的参考依据。更多还原

【Abstract】 This thesis is writing based on school-enterprise cooperation projects which are reliability of driving and design parameters software development of all terrain crane(A,B), the Project Number is 200822010100145 and 2009220101001350, and the Jiangsu Province special fund for science and technology achievements which is the research and industrialization on Large mobile crane, the Project Number is BA2007038. With the vigorous development of energy, transport and other major projects in China as to the global, the market demand for all terrain crane is rapid growth. Multi-axis steering system as the main components of large special vehicles, construction machinery and other major technologies and equipment, which has important strategic significance in enhancing ability of independent innovation of major technical equipment and enhancing Country’s economic strength. At present, the building of theory platform of large multi-axis vehicle is just starting, steering technology is turning from mechanical hydraulic power steering to the direction of combining hydraulic power steering and Electronically controlled. The control of Security steering mode is still groping. As to the studying on vehicle handling and stability has no precedent, it lead to the development lags behind of Overall industry in Large multi-axis vehicle in China, therefore, the researching on multi-axis steering of technology, vehicle safety, reliable steering is particularly important.This paper is researching in-depth on Dynamic model manipulation of Multi-axis Steering Vehicle, virtual prototype simulation of complex systems and experimental rsearch,secondary development, steering control algorithm for multi-axis and so on.Mathematical model is a key core technology of engineering practice and the basis of multi-axis steering of research. This paper established Linear model of two degrees of freedom and Linear model of three degrees of freedom of multi-axis steering vehicle, derived the transfer function from front corner to yaw rate, sideslip angle and vehicle body side angle under the conditions of meeting Ackerman’s law and the steady-state gain expressions during thenm, got the Vehicle stability factor expression and the factors which affect vehicle steering stability. Analysised the relationship of the projection distance to the vehicle body of centroid and the steering center of the vehicle under the conditions of the other side of the angle control strategy. Respectively analyzed in low-speed, high-speed conditions, the Vehicle steering performance.the impact on vehicle steering performance under the model of front wheel steering vehicle, all-wheel steering vehicle and electronic control steering the vehicle steering performance.Based on the dynamic manipulation model of Linear three degrees of freedom,builded the model of nonlinear three degrees of freedom,cosidered importantly tire nonlinear cornering stiffness impact on vehicle steering performance and conducted a case study.The moment of friction between tire and the ground is two to three when steering in situ than driving steering. Tire cornering performance in situ is important to steering system matching. Taking into account that the empirical formula of steering resistance in situ couldn’t describe the relation between steering resistance torque and tire rotations, we conducted real vehicle tests for steering resistance in situ, and also introduced the "magic formula" and Lugre model into the analysis of steering resistance in situ, and got good agreement. Testing and analysis indicate that they have nonlinear relationship between steering resistance torque and tire rotations, the resistance increased with the increase of the wheel rotation, and in finally tended to a constant value.Considering the problem that the steering rods and steering tie rod appeared breaking when all terrain crane is in use,we conducted a spot steering real vehicle testing and virtual prototype simulation for some seven-axis vehicle,the simulation results are consisitence with the experimental results,and also we got the trend of bar force. In it does not change the linkage of parameters steering and ensure that wheels meet the Ackerman Law context, We optimized design steering cylinder size and location parameters, significantly reduced the stress state of steering Linkage and steering tie rod, Increased the reliability of steering Linkage and steering tie rod. Morever, this design has been used by businesses and successfully applied to other product design. Hydraulic steering system is an important part of all terrain crane. According the actual structure of constant current valves, emergency valves and diverter, it builded each virtual prototype simulation model, analyzed their performance, and also conducted bench testing and validation. Based on these, it builded the virtual prototype simulation model of steering-hydraulic integration, and also conducted vehicle testing when the vehicle steering in situ, passed the verification of test results, Identified the correctness of multi-axis turning vehicle virtual prototype model.Because it needed the pressure of the hydraulic system required which was different when the vehicle Pivot steered and drive steered, it could appear the problem of sharp increasing in hydraulic system pressure and mutating of bars force when the wheels turn to the "limit"position, we researched and improved the hydraulic steering system.According the characteristics of all terrain crane, by the software of AMESIM, we developed the hydraulic components library of hydraulic steering system, used ADAMS, we developed parametric Model of mechanical system and optimizer, based on these, we used Visual Basic to develop the platform of the simulation and analysis of steering system for multi-axis steering vehicle. It greatly improved the efficiency and accuracy of design, improved reliability. Now, this paltform has been used by business sucessfully, and also successfully applied to the development and analysis of the appropriate product.At present, the research on handling and stability of large multi-axis steering vehicles just start at home, there is no experimental research on the whole vehicle. In this thesis, it conducted firstly the whole vehicle test of handling and stability of all terrain crane, selected a six-axle vehicles, and then conducted the snake test and steady-state circular test for the whole vehicle. The next, it simulated and analysed the virtual prototyping, further verified the validity of the model. It provided a reference for handling and stability of multi-axis vehicle.In order to reduce tire wear of multi-axis, we improved the handling model of multi-axis steering vehicle, by controling the corner of the wheel axles of any two to control the corner of the other wheel axle, combining the model of multi-axis steering vehicle with the handling model of two-axle vehicle. So some of steering control algorithm of two-axle vehicle could be used in multi-axis vehicle, improved the versatility of some of the control algorithm.By introducing the method of yaw moment control to the mechanical steering vehicle, to improve the steering performance of mechanical steering vehicle included.Using the zero steady-state error tracking control theory, we designed tracking controller of three degrees of freedom multi-axis turning vehicles, analyzed and compared that this controller was impact on the steering performance of all terrain crane. Simulation results show that all terrain crane which used the tracking controller had good tracking performance, could improve the steering performance of vehicle according to actual needs, and guarante the safety and handling stability of all terrain crane.In this paper, it used the research methods of thecombination of virtual simulation and real vehicle testing, depth research on the performance of hydraulic steering system and complex mechanical system in steering. Achieved theoretical analysis and experimental validation with each other and promote each other, orovided theoretical support for the designing of multi-axissteering vehicle, provided some reference for the research of the handling and stability of multi-axis steering vehicle.更多还原