【作者】 陶建国；

【导师】 邓宗全；

【作者基本信息】 哈尔滨工业大学 ， 机械设计及理论， 2009， 博士

【摘要】 月球探测车(简称月球车)移动系统是月球着陆探测必不可少的设备,是月面巡视勘察和取样返回的主要实施工具,其运动学和动力学性能的优劣,直接关系到探测任务的完成与否。本文提出并深入研究了具有串联多关节悬架的六轮月球车移动系统,主要开展了以下几方面的工作。对月球车移动系统总体设计中的关键技术进行了深入研究。在对移动系统构型综合和分析的基础上,提出了兼有被动和主动两种地形适应方式的混合适应型六轮移动系统,总体方案采用六轮独立驱动以及通过连杆差动平衡机构连接的串联多关节悬架,以保障各车轮均载及良好的牵引性能。在总体设计的基础上,以外包络尺寸最小为目标函数,将运动能力保障条件转化为几何约束条件,进行了移动系统机构尺寸的优化设计计算,确定了移动系统的技术参数。在此基础上,进行了移动系统本体结构设计,采用了带有轮刺的圆柱—圆锥形薄壁轮体、陶瓷轴承以及金属橡胶减振器等技术,以解决月面环境适应性设计问题。根据结构设计,建立了移动系统Pro/E三维实体模型和ADAMS仿真模型,为样机研制和仿真分析奠定了基础。本文对所设计的移动系统的运动性能进行了深入研究。为了充分发挥该六轮移动系统混合适应型的优点,根据系统的特点设计了几种不同的运动模式,并阐述了各运动模式的运动原理,为移动系统的地形通过性分析提供了依据。在归纳分析了移动系统失去地形通过性的几种常见类型基础上,确定了系统地形纵向通过性和横向通过性的几何条件。对于移动系统的障碍通过性能力,根据月球车运动速度低的特点,采用了准静力学方法进行研究,建立系统的准静力学平衡一般方程,研究系统越障时的临界状态和通过能力;鉴于两轮同时越障难度最大,利用准静力学平衡方程,并确定出运动约束几何条件。对移动系统在被动适应和主动适应两种方式下,两轮同时爬越垂直障碍、穿越壕沟和爬坡的通过性条件分别进行了推导和计算,获得了越障能力与轮地牵引系数的关系曲线和极限条件。此外,建立相应的ADAMS越障模型,对移动系统各种运动模式下的越障通过性进行了仿真分析,并与理论计算结果进行了比较,验证了理论计算值的可信性。本文对移动系统进行运动学建模和仿真分析。应用考虑车轮滑移的轮地接触变换矩阵,并结合悬架的D—H变换矩阵,建立了该系统在三维地形中存在滑移运动的正运动学模型,进而推导了考虑滑移影响的运动速度雅克比矩阵,建立起车轮与主车体之间的运动速度关系。此外,给出了系统的逆运动学方程求解方法,建立了描述崎岖地形的路径模型,并利用ADAMS软件对崎岖月面运行的移动系统进行运动学仿真,以获得各车轮和主车体运动变化的规律。为分析移动系统的动力学特性,基于车辆——地面力学理论,通过引入和定义当量牵引系数概念,推导了松软地面环境下的轮地作用简化模型;并以此为基础,应用多体系统动力学中的凯恩方程法,建立了移动系统在崎岖地形下的动力学模型,推导出其动力学矢量方程式。对于移动系统的运动平顺性研究,鉴于系统振动理论模型及求解的复杂性,利用弹簧和阻尼模型模拟金属橡胶减振器,在ADAMS软件中构建了前轮装有减振器的移动系统运动仿真模型,对移动系统被动适应模式下,在水平硬地面和越障时的前、后车轮平台的运动平顺性进行了仿真对比,验证了所设计的金属橡胶减振器的减振效果。本文研制了具有串联多关节悬架的六轮月球车移动系统原理样机和车轮牵引特性多功能测试装置,对移动系统的圆柱——圆锥形车轮在松软沙土上的牵引特性进行了测试和分析,获得了车轮牵引特性各种指标的参数曲线,并给出了移动系统运动时车轮较适宜的滑转率范围。在构建的不同模拟月面地形环境下,对原理样机的移动速度和可控性、被动适应与主动适应两种方式的越障通过性、金属橡胶减振器的减振性能进行了重点测试,验证了理论计算和仿真分析结果的有效性;同时,为便于给移动系统的运动性能测试和分析提供比较基准,提出了综合考虑整机牵引特性的均一当量牵引系数概念,并给出了相应的测定方法。试验表明本文研制的移动系统原理样机能够在复杂、非结构化地形环境中成功运行,且具有较强的地形适应性和越障通过性。更多还原

【Abstract】 A lunar rover is the major equipment of lunar surface exploring and sample returning, and its kinematic and dynamic characteristics will directly affect execution of lunar surface explorationThis dissertation has put forward a six-wheeled lunar rover mobile system with series multi-articulated suspension, and systematically studied the mobile system. The research works focus on following aspects:The key technologies of overall design of the rover mobile system are studied. Based on configuration synthesis and analysis of rover chassis and suspension, a lunar rover mobile system in hybrid locomotion, which means the mobile system may be in either active locomotion or passive locomotion according to mobility demand, has been put forward in this dissertation. In the design concept,the rover mobile system has six individually motorized wheels and a multi-articulated suspension composed of two parts of series linkage frameworks connected by a differential balance linkage mechanism, and ensured with advantages of average weight and good traction on each wheel. Thereafter selected outline size minimizing as a object function and locomotion performances as constraints,the parameters of the rover mobile system are optimized. According to the optimal parameters, structure design of the rover mobile system has been performed, meanwhile lunar environment has been taking into serious account during design,and some technologies such as cylinder-conical wheel body with lugs, ceramic bearings,metal rubber vibration absorbers are applied to the rover mobile system. Furthermore, simulating models in Pro/E software and ADAMS software have been built up for making a prototype and simulation thereafter.Regarding to its performance analysis of the rover mobile system, locomotion modes have been designed to take advantage of its hybrid locomotion concept and be in favor of trafficability analysis of the rover mobile system, and therein mechanism and locomotion principle of the modes have been introduced. According to typical cases of trafficability loss, geometry limiting values of the trafficability of the rover mobile system have been defined along longitude and transverse. For analysis of obstacles trafficability of the rover mobile system, quasi-static method is applicable due to its very low locomotion velocity, so the quasi-static equilibrium equations have been derived to express critical conditions and solve limiting values of mobile system surmounting obstacles. Because it is the most difficult for two wheels simultaneously surmounting obstacles, quasi-static equilibrium equations and locomotion geometry constraints have been derived for analysis of two wheels climbing up a vertical obstacle, hurdling a ditch, and climbing on a slope in the passive locomotion mode or active locomotion modes respectively, curves of surmounted obstacle dimension versus equivalent traction ratio of wheel-soil and some limiting trafficability values have been obtained by solving equations. In addition, the corresponding simulations of mobile system to surmount above motioned obstacles in ADAMS have been accomplished, and the simulating results validate the correctness of theoretical calculating results by comparing with each other.Kinematics modeling and analysis of the rover mobile system in a 3-dimension terrain is another research aspect. The forward kinematics models involving wheel slips has been made on the basis of deriving wheel-soil interaction coordinate transform matrix and applying D-H coordinate transform matrix, velocity equations about the main body and wheels have been formed by Jacobian matrix. Then the inverse kinematics solutions have been farther derived, and a path model for mobile system kinematics has been described. The kinematics simulations of the rover mobile system moving on the rugged terrain have been carried out, and the variable curves of the main body have been obtained.With respect to its dynamics analysis of the rover mobile system, introducing and defining equivalent traction ratio, a simplified wheel-soil interaction model has been derived firstly on the basis of Soil-Vehicle Mechanics. The dynamics model of the rover system on the rugged terrain has been formed by applying the dynamic theory of multi-body system, Kane’s method and the simplified wheel-soil interaction model, and then the dynamic vector equations have been derived. Both for analysis of riding quality of the rover mobile system and for evading great complexity of its theoretical vibration model and computing, riding quality simulation has been carried out in ADAMS. During simulation, simulating vibration absorbers were installed on front wheels but not on other wheels, which are composed of springs and dampers to simulate metal rubber vibration absorbers. The simulation results validate the effectiveness of metal rubber vibration absorbers by comparing riding quality of platforms on front wheels and rear wheels, when the simulating mobile system moves on hard ground or climb over an obstacle.This dissertation has developed a prototype of presented rover mobile system with series multi-articulated suspension and a multi-purpose testbed to test the cylinder-conical wheel traction characteristics of the rover mobile system prototype on soft soil, traction characteristic curves of the wheels have been obtained, and that feasible wheel slips of the prototype on soft soil have been presented. Some simulating lunar surface terrains have been constructed for the mobile system prototype testing,and its locomotion performances in these simulating terrains have been tested such as mobile velocities, controllability, obstacles trafficability in passive locomotion mode or active locomotion modes, as well as function of metal rubber vibration absorbers. These testing experiments validate the correctness of theoretical computation and simulation for above locomotion performances of the mobile system. Meanwhile,in order to provide a comparability reference for testing and analysis of locomotion performances of the rover mobile system, the uniform equivalent traction ratio for full prototype traction is defined and its measuring method has been presented. Experiments prove that the rover mobile system prototype is applicable for rugged and unstructured terrain and strong capable of terrain adaptability and obstacles trafficability.更多还原