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链式可变形机器人的构形与运动研究
Alternative TitleConfiguration and Mobility Research for a Link-type Reconfigurable Robot
刘金国1,2
Department机器人学研究室
Thesis Advisor王越超 ; 马书根
ClassificationTP242
Keyword可变形模块机器人 链式 履带车 构形 运动能力
Call NumberTP242/L72/2007
Pages139页
Degree Discipline机械电子工程
Degree Name博士
2007-02-05
Degree Grantor中国科学院沈阳自动化研究所
Place of Conferral沈阳
Abstract本文的研究内容围绕中国科学院创新基金和GUCAS-BHPB基金资助的项目“可变形机器人的研究”展开,其目的是研制具有较强环境适应能力和高机动性能的可变形移动机器人系统,为我国在灾难救援和特种作业等应用领域提供技术储备。论文首先对可变形机器人的研究现状进行了概述,接下来展开了三个方面的研究工作:平台方面,提出了一种新型可变形链式结构,并进行了结构设计和实验验证;构形方面,提出了基于相似理论的构形研究方法,对链式可变形机器人的构形设计和构形转化方法进行了研究;运动性能方面,通过理论和实验分析了链式可变形履带模块机器人不同构形的转向性能、越障性能和倾翻稳定性能等。各种用于非结构环境的移动机器人机构中,模仿生物蛇原型的链式机构由于具有多于确定空间位置和姿态所需的自由度,能够有效、迅速、可靠地响应许多复杂的作业任务,但是该类系统具有转向半径大和侧向稳定性差等缺点。在非结构环境中,机器人需要通过“以变应变”才能够应对复杂多变的任务和环境。因此,论文基于偏置关节的思想,提出了一种形态和结构均能够变化的新型链式结构。机器人的单个标准模块由模块本体、连接臂和偏置关节等组成。偏置关节避免了模块间的运动干涉,扩大了机器人模块间的相对运动空间。机器人模块的数量可以根据实际需要选择,机器人通过变形可以产生多种构形,同时每种构形又具有多种步态以适应作业任务的需要。根据变形机理,研制了链式可变形机器人样机,并对样机进行了相应的原理验证实验。链式可变形机器人构形的复杂性随着模块数量和构形数量的增加呈指数增长,增加了构形设计和构形控制的难度。针对构形设计和构形转化问题,本文基于相似理论,提出了构形研究的一般分析方法,并将其归纳成为:表达(Expression)、计数(Enumeration)、评价(Evaluation)和有效性(Efficiency)等四个方面的问题(简称“Four-E Problem”)。在构形设计方面,根据模块的物理结构和邻接关系提出了用构形矩阵来表达机器人结构的拓扑信息,并在仿真环境下进行有效的描述;提出了基于组合计数原理的递归算法用于多模块可变形机器人非同构构形的计数、枚举,并根据构形矩阵所表征的拓扑信息对构形进行评价;最后根据仿真结果,给出了可变形机器人的构形设计示例。在构形转化方面,论文利用图论中的基本思想和原理对机器人的构形和构形网络进行了建模,对构形转化的路径进行了计算,对构形转化的最佳路径和中心构形的选择进行了分析;以三模块可变形机器人的构形网络为例,证实了该方法的可行性。履带式移动机器人的运动能力涉及的问题很多,包括接地比压、驱动能力、地面阻力、启动特性、转向能力、越障能力、平顺性和倾翻稳定性等。本文主要研究链式可变形履带模块机器人不同构形的平面转向特性、系统越障性能和倾翻稳定性能等。论文首先对链式可变形履带模块机器人单模块(单履带)的接地比压分布进行了研究,并对接地比压的核心区域进行了分析。在复杂的环境中,机器人运动的路径多由弯曲的道路组成,转向性能是其改变运动方向的一种重要能力。转向形式通常有滑移转向和铰接转向两种,分别适用不同的构形。论文参照杨红旗模型和Kitano模型分别对链式可变形双模块机器人和链式可变形三模块机器人不同构形下的滑移转向和铰接转向进行了理论和实验分析。移动机器人的越障性能是机器人本体和环境相互作用时所产生的一种综合特性。论文分析了链式可变形机器人系统的斜坡爬行性能、沟壑爬行性能、楼梯爬行性能和倾翻稳定性能。考虑到城市环境中,楼梯是最为典型的障碍物之一,论文重点对履带式移动机器人在踢面爬升、踢面翻越和坡度线爬行等阶段的运动条件、运动性能和影响因素进行了分析。在非结构环境中,大多数情况是坎坷不平的地面和复杂的三维地形,机器人的倾翻稳定性(或者说是抗倾翻能力)非常重要。根据Iagnemma和Papadopoulos提出的稳定性分析方法,定义机器人的倾翻稳定锥,对履带式可变形机器人变形过程中的倾翻稳定性进行了综合判定,同时通过仿真比较了机器人三种对称构形在仰俯、倾斜和偏转等组合干扰下的倾翻稳定性。稳定锥方法,为可变形机器人的倾翻问题提供了有效的理论分析手段,同时稳定锥方法还可以适用于其它轮式或腿式移动机器人的稳定性分析。理论分析和实验表明,本文研制的履带驱动链式可变形机器人平台,具有多种构形和步态以适应不同的环境和任务,具有废墟、砾石、草地、沙地、楼梯、坡度和管道等城市或野外环境的通过能力。可变形机器人机构灵巧、结构紧凑、便于携带,它不仅能够用于救援、消防、公安和环保等领域,在星球探测、国防安全等方面也有着潜在的应用前景。
Other AbstractThis research is supported by the Innovation Fund of Chinese Academy of Sciences and the GUCAS-BHPB Scholarship with the aim of research and development of a novel reconfigurable modular robot. The objectives of our research are to develop a reconfigurable mobile robot which has authorized copyright, good adaptability and high mobility and to prepare related technologies in search and rescue robotics or extreme environment robotics for our nation. This thesis begins with a review of the existing research on reconfigurable modular robot. Then the remained work includes three parts which are mechanism research, configuration research, and mobility research respectively. In the mechanism part, a novel link-type reconfigurable structure has been proposed. Moreover, a series of systems have been designed and experimented. In the configuration part, the non-isomorphic configurations and the reconfiguration planning problem have been researched. In the mobility part, the ground pressure, the steering mobility, the overcome-obstacle mobility, and the tipover stability of the link-type reconfigurable tracked modular robots have been theoretically and experimentally analyzed. In all the mobile mechanisms, the link-type structure which imitates the nature snake shows almost the best performance under unstructured environments for its redundancy. The link-type structure mechanism can effectively, rapidly, and reliably respond to various missions under unstructured environments. However, it also has its disadvantages. For instance, when turning, it needs a large radius or space and when moving over uneven terrain, it easily gets lateral tipover. Therefore, the link-type robot should change its configuration to meet the changeable environments. In this thesis, the author has proposed a novel kind of link-type structure. This type, with offset joints at both sides and with the link arm between adjacent modules, has enough flexibility to change its shape. The module body is a mobile system, while the link arm and joints play important roles in reconfiguration. The number of module can be chosen by the designer and the connection and disconnection of the modules can be finished manually. The link-type structure has many non-isomorphic configurations from reconfiguration and various gaits to adapt to the environments. Three generations of the platform have been designed and experimented to validate the mechanism principle. It has been widely recognized that when the module number increases, the non-isomorphic configurations and the complexity of reconfiguration research increase exponentially. Based on similarity theory, the author generalizes these problems into four categories as expression, enumeration, evaluation and efficiency, which is Four-E Problem in short. To effectively express and store the non-isomorphic configurations’ information, configuration matrix, configuration matrix group, and configuration matrix library have been proposed to represent the topology information of the reconfigurable modular robot. In the configuration matrix, we use sub-matrices to represent the module body, the link arm, the Yaw joint, the Yaw joint offset, the Pitch joint, and the Pitch joint offset respectively. According to combination principle, recursive algorithm has been proposed to enumerate the non-isomorphic configurations completely and accurately. A three-module reconfigurable robot’s non-isomorphic configurations have been designed and simulation has testified the algorithm's validity. The reconfigurable modular robot has a great mount of configurations and all these configurations compose of a complex network. A graph-based modeling approach for the configuration network of the self-reconfigurable robot has been proposed. The weighted and directed graph has been used in the modeling of these configurations. Each configuration is defined to be a node in the configuration network. And each reconfiguration is represented by a directed path with nonnegative weight. Graph theory and related algorithms have been applied in the configuration network’s analysis. Several applications of the graph algorithms have been used to enumerate the transformation paths, to decide the shortest transformation path and the center configuration. The configuration network is potentially suitable for practical application in self-reconfigurable robots’ configuration control, planning and optimization. The locomotive ability of tracked vehicle covers a wide area of topics including ground pressure, tractive force, ground resistance, steering mobility, overcome-obstacle ability, smoothness, tipover stability, and other issues. In this thesis, we mainly focused on research of the start-up mobility and load-bearing mobility in straight running, the steering mobility in various configurations, the overcome-obstacle mobility, and the tipover stability. The author firstly analyzes the ground pressure distribution of a single module of the link-type reconfigurable robot with only one track under the environments such as plane ground, slope, and external load. And the core ground pressure area of the track has been discussed. Steering mobility is also an important locomotive ability for the tracked vehicle since the path for a mobile under complex environments is usually curved. There are main two kinds of steering: slip steering and articulated steering, which are suit for different configurations. The steering motilities of the tracked robot with two modules and three modules under slip steering according to Yang Hongqi’s model or articulated steering according to Kitano’s model have been theoretically and experimentally studied. The obstacle-overcome ability is a holistic mobility origined from the mutual reaction between the robot and the environment. In this thesis, the author mainly concerns the mobility over the obstacles such as slope, ditch, and the stairs. Special attention has been paid on the stairs-climbing ability because stairs is one of the most typical obstacles in urban environment. Stairs-climbing ability is the crucial performance of mobile robots for urban environment operation such as urban search and rescue or urban reconnaissance. The stairs-climbing process has been divided into riser climbing, riser crossing, and nose line climbing. During each climbing process, the robot mobility has been analyzed with considerations of the kinematics and dynamic factors. Finally, stairs-climbing experiments have been made on the robotic platforms. In the unstructured environments, the terrain is usually very rough and dangerous for the mobile robots because of its easy tipover. If a tipover incident happens, it will result in a series of problems even a mission failure. Thus, tipover stability is a very important issue. After the factors and the countermeasures of mobile robot’s tipover problem have been analyzed in detail, based on Iagnemma and Papadopoulos’s research, stability pyramid and tipover stability index have been proposed to globally determinate the mobile robot’s static stability and dynamic stability. And the reconfigurable modular robot’s stability has been simulatingly tested by this technique under the combined disturbance of pitch, roll, and yaw. At last, experiments on these three symmetry configurations of a three-module robot have been made under unstructured environments. Both simulation and experiment have provided a valid reference for the reconfigurable robot’s practical mission. The novel shape shifting modular robot can change its configuration to adapt to the environment and improve its tipover stability. And the stability pyramid technique is also available for the wheeled robots or legged robots. Theory analysis and experiments in this thesis have demonstrated that the link-type reconfigurable tracked modular robot has various configurations and gaits to adapt to the environments. With high mobility under the urban environments or off-road environments, robots in such kind can overcome debris, gravels, grassland, sands, stairs, slope, and pipelines. Being flexible, compact, and portable, the link-type reconfigurable tracked modular robot has a widely application in the fields such as Urban Search and Rescue (USAR) efforts, fire fighting, public security, environment protection, and even potential applications in space exploration and national defense.
Language中文
Contribution Rank1
Document Type学位论文
Identifierhttp://ir.sia.cn/handle/173321/118
Collection机器人学研究室
Affiliation1.中国科学院沈阳自动化研究所
2.中国科学院研究生院
Recommended Citation
GB/T 7714
刘金国. 链式可变形机器人的构形与运动研究[D]. 沈阳. 中国科学院沈阳自动化研究所,2007.
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