【作者】 王鹏飞；

【导师】 孙立宁；

【作者基本信息】 哈尔滨工业大学 ， 机械电子工程， 2007， 博士

【摘要】 在地球陆地表面,有超过50%以上的面积为崎岖不平的山丘或沼泽,仅仅依靠轮式机械无法完全实现在这些自然环境中的移动。因此,设计和制造一个类似动物能够在自然环境中步行的机器,一直以来是人类追求的目标。正是这个原因,使得仿生足式机器人的研究成为机器人研究领域的热点之一。其中四足机器人由于其既有超于二足机器人的平稳性又避免了六足机器人机构的冗余和复杂性,在工程探险、反恐防爆、军事侦察等具有良好的应用前景,开展该方面的研究具有重要的实际应用价值及社会意义。本课题所研究的对象为足轮混合式四足机器人,其能很好的结合轮式机器人和足式机器人的优点,根据不同的环境变换轮式运动和足式运动两种运动方式,达到良好的运动灵活性和较高的移动速度的统一。论文主要针对两种运动形式中轮足锁定条件下的足式运动开展研究,在运动学分析、稳定性评价方法、步态规划、足力控制、嵌入式控制系统设计等方面寻求实用有效的设计方法。四足机器人具有时变的运动拓扑结构,论文首先针对机器人运动学特点及要求,提出了串并联结合分析的方法,分别对摆动腿及支撑腿的逆运动学进行了分析,解决了多足机器人无法建立整体运动学的问题。同时,为了准确的评定足式机器人的行走稳定性,论文采用支撑面压力中心至各足支撑点构成的多边型各边的最短距离来作为稳定性判定准则,并由此引出了重心最小稳定距离概念及相应的稳定裕度评定方法,讨论了干扰项、重心高度、支撑面姿态以及机器人质量等参数与稳定裕度的关系。在四足动物步态一般性描述框架下,根据不同的步态参数取值,结合机器人自身结构特点,论文规划了针对非平坦路面的间歇爬行步态和针对平坦路面的协调爬行步态,并对两种步态在稳定裕度、步行柔顺性等方面进行了对比仿真分析。最后对转弯步态和摆动足轨迹进行了规划,为机器人步态实验提供了理论依据。针对非结构环境,为了保持四足移动机器人躯体的预定位姿,并实现摆动足从自由空间到约束空间的良好过渡,本文建立了四足移动机器人的整体受力模型和虚拟悬挂模型,采用承载能力最优的约束条件对机器人足力分配进行了优化,提出了基于足力补偿的机器人躯体位姿偏差修正算法。同时论文结合改进的基于位置的阻抗控制策略,实现了摆动足从摆动相到支撑相的良好过渡和期望的足力跟踪问题。由于基于足力的机器人控制策略避免了计算复杂的多足机器人多刚体动力学,因而具有较高的实时性和可行性。最后,研制了四足机器人嵌入式分级递阶多关节运动控制系统,针对关节负载非线性特性,嵌入式系统采用带自调整权函数的模糊控制规则,实现了良好的关节速度跟踪。控制系统的集成化为足式机器人的离线控制奠定了基础。同时开展了关节速度位置跟踪测试、单足阻抗控制实验以及机器人在不同环境的间歇爬行步态、协调爬行步态行走实验,实验证明了理论分析的正确性。更多还原

【Abstract】 About fifty percent of the surface of earch is covered by dene, marish, massif and so on. Though researchers have invent many kinds of wheeled machine, designing and manufacturing a legged robot like myriapod running in natural environment is still a huge challenge. So researches on legged robot have been always an important branch of robot field. Because of the stronger loading capacity and better stability than biped mobile robot as well as simpler structure than hexapod robot and eight-legged robot, research of quadruped mobile robot has glamourous future as platform for application of medical services, environmental monitoring, terrorism prevention, and other related areas.In view of the robot running environment, the structure of multi-motion mode, four legs and wheeled foots are adopted in this vehicle system. This robot can well combine the priorities of wheeled robot and legged robot, change motion mode to stability walking or fast wheeled driving according to different environments, so realize both flexibility and higher speed. This thesis focuses on quadruped motion research and seeks practical and efficient designing methods in the fields of kinematics analysis, stability criterion, gaits planning, foot force control and emebeded control system.Because of changing motion topology structure of quadruped robot, the inverse kinematics of swing leg and supporting leg are studied by combining series and parallel analysis methods. At the same time, in order to exactly evaluate the robot stability and stability margin while walking, one general criteria is proposed, which adopts the minimal distance from supporting edge to center of pressure on ground to estimate robot walking stability. For convenience, the conception of minimal stability distance is introduced and the relations between stability and parameters such as disturb elements, height of center of gravity, obliquity of supporting plane and mass of robot are discussed.Based on the combination of characteristic analysis of animal gait and our robot structure, discontinuous crawl gait for uneven surface and coordinated crawl gait for even surface are proposed with different gait variable value. Meanwhile, two kinds of gaits are compared and analyzed by simulation in the aspect of stability margin and body compliance. At last, turning gait and sway track planning is introduced which provides theory base for later experiments.To maintain quadruped robot scheduled posture on rough terrain and realize good transition of sway leg from free space to constraints space, the whole force model and virtual suspension model of quadruped robot is established. The foot force distribution is optimized and robot posture amending algorithm is proposed based on foot force compensating. Besides, the paper applies improved impedance control based on foot position to make legs achieve good transition from sway status to supporting status and expected force tracking. Such methods avoid computing complicated multi-body dynamics, so has characteristics of high real-time and feasibility.Finally, the embedded hierarchical control system of quadruped robot is proposed. In view of nonlinear of joint load, the embedded controller adopts algorithm of fuzzy regulation with modifiable function and realizes good joint speed tracking. The integration of control system lays the foundation for quadruped robot remote control. At the same time, several experiments such as joint speed and position tracking experiment, one leg impedance experiment, walking experiments on even and uneven plane are carried out. The experiment result confirmed the validity of the designing and theoretical analysis of the robot system.更多还原