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文 件 包 含 CAD 图 纸 和 三 维 建 模 及 说 明 书 ,咨 询 Q 197216396 或 11970985目 次1 引言31.1 移动机器人的发展概况 31.2 轮腿式移动机器人的发展趋势 31.3 轮腿式移动 机器人关键技术的研究 61.4 本次设计目的及意义62 轮腿式移动机器人驱动方案设计 72.1 课题要求72.2 轮腿式机器人结构方案设计72.2.1 轮腿配置方案的选择82.2.2 轮腿式机器人的结构方案82.2.3 六轮腿的分布方案82.2.4 越障机构的设计92.2.5 车轮方案设计112.2.6 总体方案123 轮腿式移动机器人驱动装置结构设计143.1 车轮设计143.1.1 车轮直径设计143.1.2 轮宽的选择143.2 腿臂的设计 143.3 车底盘设计 153.4 机构受力分析与计算 163.4.1 机构重力估计163.4.2 受力分析163.4.3 前排轮翻越台阶时车身受力分析173.4.4 车轮驱动功率203.4.5 关节功率计算203.4.6 轮子驱动转矩计算203.4.7 在斜坡上所需的制动力203.5 驱动装置的设计213.5.1 驱动方式概述21文 件 包 含 CAD 图 纸 和 三 维 建 模 及 说 明 书 ,咨 询 Q 197216396 或 119709853.5.2 车轮电机和制动器选择设计223.5.3 腿臂驱动电机和减速器，离合器的选择233.6 总体结构图 244 零件设计 254.1 零件设计的主要方面 254.2 零件具体设计 254.2.1 车体的设计 254.2.2 长臂的设计 264.2.3 短臂的设计 264.2.4 摇杆的设计 264.2.5 车轮的设计 274.2.6 腿臂驱动设计 344.2.7 整体结构 355 性能分析 365.1 动态打滑的稳定性分析 36 5.2 爬坡步态分析 375.2.1 坡面行使 38 5.2.2 越障步态 39结论40致谢41参考文献42文 件 包 含 CAD 图 纸 和 三 维 建 模 及 说 明 书 ,咨 询 Q 197216396 或 11970985文 件 包 含 CAD 图 纸 和 三 维 建 模 及 说 明 书 ,咨 询 Q 197216396 或 11970985文 件 包 含 CAD 图 纸 和 三 维 建 模 及 说 明 书 ,咨 询 Q 197216396 或 119709851 引言11 移动机器人的发展概况随着科技的进步，人类的视野越来越开阔，对未知世界进行探索的愿望越来越强烈。迄今为止，人们已经开始了对月亮、火星等宇宙星体的探索，也开始对地下埋藏的，乃至海底沉寂的历史古迹、文化遗产、地理地貌的研究。另外，现代战争的复杂程度越来越高，反恐斗争的难度也越来越大，需要人们能够及时准确地完成各种侦察或作战任务。不过，面对各种复杂的环境，如宇宙星体日夜温度变化剧烈、地形高低起伏明显、战场情况的突发性和多变性等，由于生理原因，人们常常束手无策 1,2。可遥控控制、能够适应地形变化的移动机器人，为人类突破这些局限创造了条件。这种机器人可以适应不同环境，不受温度、湿度、空间、磁场辐射、重力等条件的影响，完成人类无法进行的探测任务。移动机器人是一种能够与外界环境交互的智能系统，在有障碍物的环境中能够面向目标自主运动，从而完成一定作业功能的机器人系统。用于军事侦察、反恐防暴等危险作业的小型地面移动机器人以其体积小、成本低、生存能力强、运动灵活等特点成为移动机器人研究领域的又一热点。由于其工作环境复杂多变,很多时候要求机器人不是避开障碍或复杂地形,而是要越过并适应它。所以,研究开发具有越障功能的小型地面移动机器人以适应各种结构化、非结构化环境是非常必要的。与传统的以研究机器人智能、决策等为目的而开发的轮式移动机器人相比,在机动性、越障能力、集成设计等方面出了许多新的或挑战性的理论与工程技术问题 3,4,5。1 .2 轮腿式移动机器人的发展趋势 轮腿式移动机器人的发展较为发达，各国都在大力研究。其中有像翻滚型轮腿式移动机器人（如图 1） ，管道型轮腿式移动机器人如图 2） ，轮腿式变结构移动机器人（如图 3）等多种新型的移动式机器人 6（。并且向着智能化，微型化发展，越来越来多的微型智能化移动式机器人出现在社会的各个行业中，并且充当着重要的角色。文 件 包 含 CAD 图 纸 和 三 维 建 模 及 说 明 书 ,咨 询 Q 197216396 或 11970985图 1 翻滚型轮腿式移动机器人 图 2 管道型轮腿式移动机器人图 3 轮腿式变结构移动机器人 据国外媒体报道，近日美国研究人员推出一款取名为“Three”的新式netbook 电脑机器人 9（如图 4） 。据介绍，该机器人的底盘结构为两个滑动轮胎，而轮胎的中间连接部分则负责承载 netbook 电脑。整个设计结构简单而且十分易于实际操作，即使没有相关的原理知识，也能够在说明书的介绍下方便控制以及拆卸安装。图 4“Three”新式 netbook 电脑机器人设计人员还表示，该机器人内部装有大功率发动机，以及最先进的机器设备。文 件 包 含 CAD 图 纸 和 三 维 建 模 及 说 明 书 ,咨 询 Q 197216396 或 11970985仅仅在安装上相应的软件与装载上主人识别系统，整个机器人将完全在顾客的掌控之下，让顾客享受到全方位服务。此外，如果顾客觉得仍然不过瘾，顾客可以安装红外线传感器以及外置摄像仪器等装置。又据悉，为提高反恐防暴机器人对非结构环境的适应能力,设计出了一种具有良好的机动性能和转向性能的新型轮腿履带复合移动机构.通过机器人机构分析与本体的稳定性分析,论证了其结构设计的可行性及好的稳定性.从而设计出了这种轮腿履带复合移动机器人 10（如图 5） 。图 5 轮腿履带复合移动机器人研制机器人的最初目的是为了帮助人们摆脱繁重劳动或简单的重复劳动，以及替代人到有辐射等危险环境中进行作业，因此机器人最早在汽车制造业和核工业领域得以应用。随着机器人技术的不断发展，工业领域的焊接、喷漆、搬运、装配、铸造等场合，己经开始大量使用机器人。另外在军事、海洋探测、航天、医疗、农业林业甚到服务娱乐行业，也都开始使用机器人。而作为一种新型探测用具，轮腿式移式机器人由于其机动性及智能化，可以从事很多人类难以亲身参与的工作。如复杂危险地形的探测、外星球的探测及一些军事领域的侦查等。机器人的爬坡和越障能力作为机器人野外适应能力的两大主要指标是地面移动机器人研究的重点内容。又由于轮腿式移动机器人大多数时候都工作在崎岖不平的地形中倾覆稳定性对这种机器人而言是非常重要的运动过程中发生的倾覆可能导致机器人驱动系统失灵、运动失控、无法复位、元件损坏乃至系统报废等一系列问题是今后轮腿式移动机器文 件 包 含 CAD 图 纸 和 三 维 建 模 及 说 明 书 ,咨 询 Q 197216396 或 11970985人研究的重点内容。真正的智能化和完全的自主移动的关键技术。导航研究的目标就是没有人的干预下使机器人有目的地移动并完成特定任务，进行特定操作。机器人通过装配的信息获取手段，获得外部环境信息，实现自我定位，判定自身状态，规划并执行下一步的动作 11,12。1.3 轮腿式移动 机器人关键技术的研究正如人类活动范围和探索的空间是人类进步的标志一样,机器人的智能同样体现在运动空间的大小上。为了获得更大的独立性,人们也对机器人的灵活性及智能提出更高的要求,要求机器人能够在一定范围内安全运动,完成特定的任务,增强机器人对环境的适应能力。因此,近年来,移动机器人特别是自主式移动机器人成为机器人研究领域的中心之一 7。(1) 轮腿式移动机器人的机构形式根据实际运用环境的需求 综合轮式和腿式运动机构的优点，设计了一种多驱动模式的轮腿式移动机器人整个机器人由六个结构左右对称的运动单元和车体构成每个运动单元具有一个转向臂、一个摆臂和两个电动轮(驱动轮和爬行轮。对于运动在不平坦地形中的移动机器人而言,其倾覆稳定性非常关键.对称结构的轮腿式机器人，它有六个独立的轮腿运动单元,能够变化多种构形.采用动态能量稳定锥方法和倾覆稳定性指数对机器人的稳定性进行综合评价,建立了一个模糊神经网络白适应控制系统.根据稳定性指数值,该系统可以实时改变机器人的构形和速度,保证其倾覆稳定性.正弦路面上的仿真结果表明,该系统所产生的动作实时性好、可靠性高,能够降低机器人白主越障过程中的危险 14,15。(2) 轮腿式移动机器人的组成: A 轮腿式移动机器人的 驱动装置,B 轮腿式移动机器人的导向装置,C 轮腿式移动机器人的换向装置 D,轮腿式移动机器人的制动装置.1.4 本次设计目的及意义轮腿式移动机器人的驱动装置是一种复合移动系统，结合轮式和腿两种移动方式的特点，世界各国均投入了大量研究。课题对机器人腿式和轮式移动原理进行了解和掌握，在此基础上对两种移动方式进行综合，设计出一种适合野外非结构环境下的移动机器人驱动装置，在机构上有所创新，机器人能够在复杂路面上行走、文 件 包 含 CAD 图 纸 和 三 维 建 模 及 说 明 书 ,咨 询 Q 197216396 或 11970985具有较强的越障能力。在机械 CAD 环境下设计驱动装置的总体方案和结构，各种机电元件进行选型设计，并对机器人越障行为进行分析与研究。2 轮腿式移动机器人驱动方案设计2.1 课题要求 课题要求对机器人腿式和轮式移动原理进行了解和掌握，在此基础大对两种移动方式进行综合，设计出一种适合野外非结构环境短的移动机器人驱动装置，机器人能够在复杂路面大行走、具有较强的越障能力。在机械 CAD 环境短设计驱动装置的总体方案和结构，各种机电元件进行选型设计，并对机器人越障行为进行分析与研究设计技术要求：1每个轮子独立驱动，采用环境适应能力好的六腿式结构。2重量短于 45Kg ，外形尺寸长度不超过 800mm，宽度不超过 600mm 。3机器人最大移动速度 10Km/h，具备越障和爬坡能力。4要求能够翻越 250mm 高的障碍,能够爬 15的斜坡。2.2 轮腿式机器人结构方案设计2.2.1 轮腿配置方案的选择轮腿式移动越障机器人依靠轮与腿的共同作用来行使与越障,因为其翻越障碍时需要很好的平稳性,所以考虑用对称的结构对轮腿式机器人的平衡性有很大的帮助,在所考虑的 4 轮腿式和铝六轮腿式机器人中,显然,六轮腿式较四轮腿式有着更好的平衡性与抗震性,故选用六轮腿式结构.2.2.2 轮腿式机器人的结构方案因为在行使的过程中,轮腿机器人是需要越障行使,其越障机构的形式就是我们研究的重点,如何分配这六个轮子,每个轮子是什么样的驱动,怎样 控制其越障,各个轮子在越障时实现怎样的动作也是我们应该考虑的.文 件 包 含 CAD 图 纸 和 三 维 建 模 及 说 明 书 ,咨 询 Q 197216396 或 11970985在设计时考虑了两种形式机构1) 摇臂-转向架式六轮腿式行使机构其结构简图如图 2-1 所示,其结构有两个独特之处: (1) 各轮有独立控制转机构;(2) 通过差速齿轮轴连接两侧行使机构,并将机器人机体与差速轴箱体固定.图 2-1 摇臂转向架式六轮腿移动机器人的结构简图2） 独立驱动六轮腿式移动机器人驱动机构该机构简图如图 2-2 所示，本机构的六个车轮为独立驱动，每个车轮都有各 自的直流电机驱动，另外，每一条腿都有一个独立的直流伺服电机驱动，且配有增量编码器。每一条轮腿构成一个独立的伺服驱动系统Acta Astronautica 64 (2009) 925934/locate/actaastroDesignofahighperformancesuspensionforlunarroverbasedonevolutionBaichao Chena, Rongben Wanga,YangJiab, Lie Guoa,LuYangaaIntelligent Vehicle Group, Traffic college, JiLin University, ChinabChina Academy of Space Technology, Beijing, ChinaReceived 7 March 2008; received in revised form 17 October 2008; accepted 4 November 2008Available online 21 December 2008AbstractIn this paper, we propose a new suspension for lunar rover called obverse and reverse four-linkage suspension (ORF-Lsuspension for short). Its two components are designed based on the evolutions of bogie and rocker. Firstly, we analyze thecharacter of bogie and research the approach to improve its performance. Based on that research, an evolved mechanism ofbogie is proposed, named obverse four-linkage. It has better capacity than bogie. In addition an evolved mechanism of rockeris also proposed, named reverse four-linkage. The bogie, rocker and their evolved mechanisms can compose four availablesuspensions including the interested ORF-L suspension. Because ORF-L suspension is composed of two evolved mechanisms, ithas the highest performance. In order to check that, the performance comparison between ORF-L suspension and rocker-bogiesuspension are carried out based on simulation. Finally, a prototype rover with ORF-L suspension is designed and manufactured.It shows excellent performance as expected.Crown Copyright 2008 Published by Elsevier Ltd. All rights reserved.Keywords: Suspension; Four-linkage; Lunar rover; Exploration vehicle1. IntroductionWheeled locomotive system can move in variouskinds of soils with high efficiency. And not only are itsimpact load, energy consumption and abrasion smaller,but also its configuration is simpler than other types oflocomotive systems, for example tracked locomotivesystem. Therefore wheeled locomotive system is usedbroadly in planet exploration. However, it is weak intrafficability, in order to enhance it, all kinds of sus-pensions are developed. For example, rocker-bogieCorresponding author.E-mail address: (B. Chen).0094-5765/$-see front matter Crown Copyright 2008 Published by Elsevier Ltd. All rights reserved.doi:10.1016/j.actaastro.2008.11.009suspension is used in Sojourner, Rocky7, MER, FIDO,etc by NASA 1,2; parallel architecture of the bo-gies and spring suspended fork suspension is used inSHRIMP by Swiss federal institute of technology, etc.3; pentad grade assist suspension is used in Mcro5by ISAS Japan 4,5; RCL Concept series and CRABare also used in prototype vehicles for mars by ESAand ASL 6,7, and so on. Even though all suspensionsare designed to perform well in rough terrain, eachdesign has its advantages and drawbacks. For example,the SHRIMP with parallel architecture of the bogiesand spring suspended fork suspension has excellentclimbing capacity, but its platform stationarity is not sowell as a result of rear wheel being fixed on platformdirectly. Therefore it is still necessary to develop a new926 B. Chen et al. / Acta Astronautica 64 (2009) 925934suspension to enhance the performance of wheeledlocomotion system completely.Because Sojourner and MER had worked success-fully on Mars and all their suspensions are rocker-bogiesuspension, rocker-bogie suspension is very worth re-searching. Therefore, this paper starts with the analysisof rocker and bogie, and then proposes a new suspen-sion mechanism based on the evolutions of rocker andbogie.2. Obverse four-linkage mechanism design2.1. The character of bogieBogie is a component of rocker-bogie suspension.The bogie of Mar rover Sojourner is shown in Fig. 1.Because it is a curved bar, its stability is not strong andit is easy to overturn on uneven road.The pivot point of bogie and the center points ofwheel 1 and wheel 2 make the angles afii9826 and afii9825, and forma triangle (see Fig. 1). Through analyzing the stabilityoftriangle,weknowthatthebiggertheangle afii9825 themoreeasily the triangle turns clockwise; the bigger angle afii9826the more easily the triangle turns counter-clockwise.Additionally, when one wheel is uplifted relative to theother one on uneven road, the bigger the angles afii9825 and afii9826the more the variation of wheel load is and the biggerthe probability of bogie turnover is.Inordertoenhancethestabilityofbogieanddecreasethe variation of wheel load, it is necessary to adjust thebogie to make the angles afii9825 and afii9826 less or even zero asthe bogie of Rocky7 8 shown in Fig. 2. Rocky7 is a re-formative type of Sojourner by NASA and its bogie is astraightbar.Butthatadjustmentalsodecreasestheclear-ance between bogie and ground, which leads the bogielikely to be blocked with obstacles. Although to shortenthe length of bogie as Rocky7 can decrease the proba-bility blocked with obstacles, but which also decreasesthe stability. Thus, for bogie, stability, wheel loadFig. 1. Sojourner and its rocker-bogie suspension.invariance and ground clearance restrain each other. Inorder to make a tradeoff, a proper afii9825 or afii9826 ought to beexistent.The climbing of bogie can be regarded that thetorque which is loaded in bogie to help wheel climb(active torque) overcomes the torque which is loadedin bogie to prevent wheel from climbing (negativetorque). For bogie, no matter how to adjust the shape,length and location of pivot, the climbing capacity isstill weak. That is because the torque for wheel 1 toclimb and that for wheel 2 to climb are restrained eachother and those adjustments cannot break this restraint.In other words, the weak climbing capacity is inher-ent for bogie and cannot be enhanced by optimizing.Thus we must design a new mechanism to break thatrestraint.2.2. Approach to enhance climbing capacity of bogieThrough Section 2.1, we know that the bogie stabilityand the wheel load invariance of Rocky7 are better thanthose of Sojourner. Therefore the research starts withthe bogie of Rocky7.ThecorrelativeparametersaregiveninFig.3(a)whenwheel 1 contacts obstacle. The forces and torques ofwheel 1 giving bogie are F1and Tf1. The forces andtorques of wheel 2 giving bogie are F2and Tf2.Thedistances between the pivot point of bogie and the cen-ters of wheel 1 and wheel 2 are, respectively, L1andL2. The active torque for climbing is T1,clockwise.Thenegative torque for climbing is T2, counter-clockwise.The arms of F1and F2are Lb1and Lb2. The anglesbetween bogie and the arms of F1and F2are, respec-tively, afii98281and afii98282. The angle between horizon and F1is afii98261. The angle between horizon and F2is afii98262.Theangles between bogie and horizon are, respectively, afii98251and afii98252.When wheel 1 contacting obstacle, as a rule0180(afii98291+ afii98351) when the two load linkages turn counter-clockwise as the result of wheel 3 climbing up obstacle.According to Eqs. (5) and (6), afii9835= f (afii9829) is an increasingfunction. Based on above analysis, it is not difficult todeduce afii98352afii98351. Therefore the rover with reverse four-linkage mechanism has better cab stationarity than therover with rocker when wheel 3 climbs up obstacle.With the same way, it is not difficult to draw the sameconclusion when wheel 3 goes down into crater.4. Obverse and reverse four-linkage suspensiondesignThroughSections2and3,weknowthatobversefour-linkage mechanism (OF-L) has the better performancesthan bogie and reverse four-linkage mechanism (RF-L)has also the better performances than rocker. It is rea-sonable to confirm that the suspension composed ofOF-L and RF-L is high-performance (this conclusion isalsovalidatedbysimulationinSection6).Withanavail-able combination of OF-L and RF-L being achieved,930 B. Chen et al. / Acta Astronautica 64 (2009) 925934a new high performance suspension is born, named ob-verse and reverse four-linkage suspension (ORF-L sus-pension), shown in Fig. 8. ORF-L suspension includessix linkages and seven pivot points. The installation anduse methods of ORF-L suspension are the same as thoseof rocker-bogie suspension.ORF-L suspension inherits the advantages of OF-Land RF-L, thus it has higher performances than bogie-rocker suspension in climbing obstacle, cab stationarity,wheel load invariance and suspension stability.5. Combination mechanisms analysisOF-L, RF-L, bogie and rocker can compose fouravailable suspensions, named, respectively, ORF-L sus-pension, OF-L-rocker suspension, bogie-RF-L suspen-sion and bogie-rocker suspension, shown in Fig. 9.Fig. 8. Rover model with ORF-L suspension.Fig. 9. The combination mechanisms: (a) ORF-L; (b) OF-L-rocker; (c) Bogie-RF-L; (d) Bogie-rocker.Table 1Performance comparisons of the four suspensionsPerformance Climbing obstacle Cab stationarity Mechanism stability Wheel load invariance Weight and complexityORF-L A A B B COF-L-rocker B C B B BBogie-RF-L B B C C BBogie-rocker C C C C ANote: excellent A; good B; fair C.ORF-L suspension and OF-L-rocker suspension areall novel suspensions without being used. The bogie-RF-L suspension is similar to the suspension of RCLConcept-C rover by ESA, and the bogie-rocker suspen-sion is used in Sojourner, MER and other prototyperovers by NASA.We think that the performances of suspension can bedecided by the performances of its component mecha-nisms more or less, and based on that, the relative per-formances of above four suspensions can be inferred.The result is shown in Table 1.6. Simulation validation6.1. Simulation modelAimingattheORF-Lsuspensionroverandthebogie-rocker suspension rover, some simulation comparisonworks are carried out based on ADAMS. In simulation,no control is set and all wheel velocities are a constantvalue.According to the design requirements of Chineselunar rover, the outline size and mass of the ORF-Lsuspension rover model (ORF-L rover for short) aredetermined. For a fair comparison, the bogie-rockersuspension rover model (Rocker-Bogie rover for short)is designed with the same size and mass of ORF-Lrover.The same parameters are as followed: outline sizeis 1.5m1.0m0.8m; rover mass is 200kg; wheelmass is 3.5kg; centroid height is 500mm; diameter andB. Chen et al. / Acta Astronautica 64 (2009) 925934 931Fig. 10. The structures and sizes of two rover models: (a) ORF-L rover; (b) Rocker-Bogie rover.Fig. 11. The course of the two rovers crossing the different height obstacles.Fig. 12. Comparison of friction coefficients of two rovers.widthofwheelare300and200mm;wheeltrackisallthesame, and the wheelbase between front-wheel and rear-wheel is 1200mm. In the course of simulation, gravityacceleration is set at 9.8m/s2and wheel velocity is at0.3rad/s. The structures and sizes of ORF-L rover andRocker-Bogie rover are shown in Fig. 10.932 B. Chen et al. / Acta Astronautica 64 (2009) 925934Fig. 13. Comparison of invariance coefficients of two rovers.Fig. 14. Comparison of cab pitch angle of two rovers.6.2. Simulation and comparisonToincreasethefrictioncoefficientbetweenwheelandground until Rocker-Bogie rover and ORF-L rover allcan climb over the 250mm-high obstacle, and then tomeasure some interesting parameters. Fig. 11 shows thecourse of the two rovers crossing the different heightobstacles (the arrows in Fig. 11 are the forces of groundgiving wheels).6.2.1. Comparison of friction coefficientThe friction condition needed in climbing can re-flects the climb capacity of rover. The smaller the fric-tion coefficient the stronger the climbing capacity is.Fig. 12, respectively, shows the friction coefficients offront wheels, middle wheels and rear wheels of the tworovers during crossing the 250mm-high obstacle. Dur-ing the time of zone A, the front wheels of ORF-L rovercontact, climb up and detach from obstacle. With theB. Chen et al. / Acta Astronautica 64 (2009) 925934 933same state, zone B, C and D, E, F corresponds, respec-tively, to middle, rear wheels of ORF-L rover and front,middle, rear wheels of Rocker-Bogie rover. Obviously,the friction coefficients leap and come to peak at themoments of wheels contacting obstacle, therefore thosemoments are the most difficult for wheel to climb. Ac-cording to Fig. 12 the friction coefficients of ORF-Lrover are all less than 0.7, but for Rocker-Bogie roverthe maximum friction coefficient is close to 1.0. There-fore the climb capacity of ORF-L rover is stronger thanthat of Rocker-Bogie rover, which is the same as theconclusion of the analysis in Sections 4 and . Comparison of invariance coefficient of wheelloadThe invariance coefficient of wheel load is also animportant performance index for rover. It reflects thevariation degree of wheel load in rough terrain, andthe smaller the value the less the wheel sinkage is andthe more the wheel tractive power is. The invariancecoefficient is defined as followed:Invariancecoefficient=current wheelload initialwheelloadinitialwheelloadFig. 13, respectively, shows the load invariance coef-ficients of front wheels, middle wheels and rear wheelsof the two rovers during crossing the 250mm-high ob-stacle. Obviously, the coefficients of ORF-L rover aresmaller than those of Rocker-Bogie rover.6.2.3. Comparison of cab pitch angleCab stationarity can be evaluated through measuringthe pitch angle of cab, and the smaller the angle thebetter the cab stationarity is. From Fig. 14, it is obviousthat the pitch angle of ORF-L rover cab is nearly sym-metric and the maximum pitch angle of ORF-L rovercab is smaller than that of Rocker-Bogie rover cab.6.3. Simulation conclusionsIn simulation, the ORF-L rover performs more ex-cellent performances than Rocker-Bogie rover in climb-ing obstacle, wheel load invariance and cab stationarity.That verifies the conclusions of the theory analysis inSections 35. Meanwhile, we find there are also somethe same trends in the performance curves of two mod-els. We think that those improvements and similaritiesjust reflect the effect of evolving.Fig. 15. The prototype lunar rover with ORF-L suspension.7. ExperimentsA prototype lunar rover with ORF-L suspension isdesigned, shown in Fig. 15. Because the key technolo-gies of ORF-L suspension in manufacture and instal-lation are the same as that of rocker-bogie suspension,ORF-L suspension has good practical value.Some interesting tests are carried out on lunar sim-ulation ground to check the practical performances ofrocker-bogie suspension. In test, the rover passes overvarious typical blocks and craters facilely, and not onlyis its cab relatively stationary but also the loads in sixwheels is relatively homogeneous. The test states arepartially shown in Fig. 16.8. ConclusionIn this article we use an effective method to de-sign the suspension of lunar rover, which is evolution.Based on that, we design a high-performance suspen-sion, called ORF-L suspension and evaluate the relativeperformances of four different evolutionary suspen-sions. Because ORF-L suspension has the all-roundexcellent performance, it can make rover interestingto cross higher obstacles rather than to avoid and godown steeper slope instead of abandoning. Its goodcab stationarity is in favor of the on-board instrumentsto work. Its good wheel load invariance can decreasewheel sinkage and produce more tractive power. Itskey technologies in manufacture and installation arethe same as those of bogie-rocker suspension, whichmakes it has high working reliability.934 B. Chen et al. / Acta Astronautica 64 (2009) 925934Fig. 16. The test to climb block and cross crater.Sofarwehavenotfoundthesimilarsuspensionstruc-ture with ORF-L suspension all over the world. Chinahas determined to carry an exploring vehicle to lunar in2012 and as a forecast, the n