【作者】 黄博；

【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】 移动机器人不仅需要适应已知结构化环境,还需适应非结构化未知环境。足式机器人具有障碍跨越、沙地及崎岖等特殊路面行走能力,可用于工程探险勘测、反恐防爆、军事侦察等人类无法完成或危险工作,在移动机器人领域具有重要的研究意义。由于四足机器人静态稳定性能大大优于双足机器人,而且机构的冗余和控制复杂程度比六足和八足简单,因此四足结构在足式机器人领域具有较好的综合性能。足式机器人具有越障能力强、速度较低的特点,而轮式机器人具有与足式机器人互补的特点,本文以轮足复合式四足机器人系统为研究目标,结合轮式机器人和足式机器人的优点,实现良好的运动灵活性和较高的移动速度。课题在机器人结构设计及系统实现的基础上重点研究机器人稳定运动的能力及其生物控制特性。通过结构形式比较分析,研制成功一种轮足复合运动方式四足移动机器人。该机器人采用鳄鱼式结构,单足具有3个关节转动自由度和一个足底滚进轮,单足具有独立的DSP控制节点,负责采集传感器信号、状态判断以及足内关节控制,采用CAN总线实现DSP控制节点和嵌入式主控计算机之间通讯,由主控计算机实现机器人的任务。该结构使得机器人具备轮式机器人的快速移动能力及足式机器人的灵活越障能力。研究了该机器人的滚进能力、运动学、运动空间以及重心求解方法,为机器人的稳定性分析及步态规划提供依据。研究机器人的步态对机器人稳定行走具有重要的指导意义。采用稳定裕度作为四足机器人静态稳定的判据,并以象限为分界线明确了不同初始落足点时机器人迈腿的可能性;建立了步态描述的数学模型,基于模型对步态进行了分类,明确了静平衡步态的模型参数;基于迈腿次序将所有步态划分为24种类型,并对比分析了24种步态的三个基本特性参数:运动空间需求、最小稳定裕度以及机器人的运动协调性。基于机器人平台实际参数进行了平面直行、平面转向步态的仿真研究;此外,基于ZMP理论进行了机器人动平衡步态研究和仿真,得到固定ZMP点步态、随动ZMP点步态及比例步态;这些步态研究为机器人多运动方式提供了理论基础。为增强移动机器人的环境适应能力,提出了基于投影分析法结合平面静平衡步态理论的楼梯爬越步态规划方法;从运动空间需求最小、稳定裕度最大、步态协调性最好三个方面对楼梯爬越步态进行了仿真研究,得出各种需求下可用的步态参数;研究了本机器人的侧爬步态及其参数;为机器人的典型环境移动步态选定提供了理论依据。为协调机器人多足控制,采用中枢神经模式控制机器人的步态。基于互抑神经元建立了振荡器模型,并利用振荡器模型组建了四足机器人的CPG(Central Pattern Generator)控制网络;采用计算机仿真法分析了CPG模型各参数对输出的影响并整定了机器人CPG控制网络的参数;建构了机器人步态的CPG控制模型,提出了阈值法步态占空比控制方法,实现不同占空比步态的切换,阐述了基于CPG理论的步态切换方式;基于CPG网络的自适应特性建构了机器人的反射机制,增强了机器人的环境自适应能力。最后,搭建了基于三级控制体系的机器人实验系统,进行了不同占空比下的平面直行、平面转向、楼梯爬越、平面滚进等运动性能实验,实验结果验证了机器人系统设计及理论分析的有效性。更多还原

【Abstract】 Walking robot is not only required to adapt to the known and structured environment, but also the unknown and unstructured environment. Since the legged robot is capable of navigating obstacles, sand land and rugged road, it possesses good environmental adaptability and could be applied to the tasks which are dangerous or couldn’t be accomplished by human beings, such as engineering exploration and survey, anti-terrorism detection, military reconnaissance, etc. Quadruped robot possesses the preferred all-round performance in legged robot field for its better stability than biped, and the mechanism and control system is simpler than hexapod and octopod. The shortcoming of legged robot is the low velocity, whereas the wheeled robot possesses the complementary characteristics. Therefore, the purpose of this thesis is aimed at the study of a wheel-leg hybrid quadruped robot, which could combine the virtue of legged robot and wheel robot. On the basis of robot platform design, the thesis focuses on the correlative research of the stable gait and biological control.Based on thorough analysis, a wheel-leg hybrid crocodile-like quadruped robot is proposed. Each leg of the robot possesses three joints and one wheel on the toe, by which the robot could move ahead quickly and step over obstacles. There is also independent DSP controller node for each leg, which is responsible for sensor signal collection, state judgment and inner joints control. And moreover, the embedded master computer communicates with DSP nodes via CAN bus. So the robot is capable of rapid mobility as the wheeled robot and flexibility for stepping over the obstacles as the legged robot. Rolling ability, kinematics, working space and Center of Mass solve method is studied, which provides the basis for stability analysis and gait plan.Balanced gait study is important guide for robot stable walk. Taking stability margin as the criterion of the robot’s stability, and quadrant boundary as the criterion of swing leg possibility for the robot in different initial posture, gait mathematical model is established, which is classified by duty facotr; and statically balanced gait parameters are proposed. All quadruped gaits are classified into 24 kinds by swing orders; three essential characteristic parameters are contrasted with all 24 kinds of gaits: working space demand, minimum stability margin and body adjustment harmony. According to the robot actual structure parameters, plane walking and turning gaits are simulated. Dynamic balanced gait is simulated based on ZMP (zero moment point) theory, which establishes the theoretical basis for multi-locomotion ways of robot.In order to enhance the ability of environmental adaptation, stair climbing gait study based on projection analysis method is proposed. Stairs climbing gaits of minimum working space demand, maximum stability margin, and the most harmony body adjustment are simulated, and furthermore to obtain the suitable gait parameters for all necessities. The lateral stair climbing gaits and parameters are studied, which provide the theoretical basis for robot locomotion in classical environment.Based on mutual inhibition neurons, the oscillating model is established, by which the CPG (Central Pattern Generator) control network of the quadruped robot is developed. The impact on the output by parameters of CPG model is analyzed by computer simulation, and the CPG control network parameters of the robot is set. The CPG control model of the robot’s gait is constructed. Output threshold is adopted for different duty factor gait control, and the gait switching mode by CPG is described, then robot reflex mechanism is established based on the adaptive property of CPG network, which testifies the excellent environment adaptation ability of CPG gait control method.Finally, an experiment robot platform based on 3-hierachical control architecture is established. Plane walking of different duty factor, turning, stairs climbing and rolling ahead experiments confirmed the validity of the designing and theoretical analysis of the robot system.更多还原