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Alternative TitleGait Planning for A Quadruped Robot in Confined Environments
Thesis Advisor王伟
Degree Grantor中国科学院大学
Place of Conferral中国科学院自动化研究所
Degree Discipline控制工程
Keyword四足机器人 步态规划 约束环境 Quadruped Robot Gait Planning Confined Environment
Abstract四足机器人具有很强的机动性和环境适应性,可适用于复杂的工作环境。四足机器人在复杂环境下的适应性行走是四足机器人走向实用化的前提之一,复杂环境下的四足机器人步态规划已成为四足机器人研究的重要方向。本文就四足机器人中枢模式发生器模型的改进及约束环境下的步态规划展开了初步研究,提出了四足机器人在行走过程中的一种重心高度调整方法,进行了理论分析及仿真研究;研究了凹陷区域跨越的步态规划算法,并在四足机器人上进行了实验研究。本文的核心工作概要如下: 1.学习了基于Hopf模型的中枢模式发生器对四足机器人运动的控制,分析了Hopf模型的变量对输出信号的影响;针对步态变换产生相位错位问题,改进了基于Hopf振荡器的中枢模式发生器模型,以延迟相位,从而实现四足机器人的步态变换。 2.提出了将关节振荡中值平滑过渡模型和节律运动结合的控制方法,以实现四足机器人行走过程中的重心高度调整。机器人的重心通过关节振荡中值的平滑过渡模型调节,设定该模型的过渡时间可生成平滑的过渡时间曲线。四足机器人行走时因身体倾斜会产生剧烈颠簸,本文利用中值偏移量补偿来消除调整重心过程中产生的颠簸。另外,髋关节的振荡幅值调整保证了四足机器人在重心高度调整时仍保持匀速运动以便于控制。 3.基于中枢模式发生器,提出了四足机器人跨越凹陷区域的步态规划方法。步态规划方法由运动控制器和步态规划算法组成。步态控制器首先采用基于Hopf模型的中枢模式发生器生成标准输出信号,再通过幅值调节模型调节振荡信号的正半轴和负半轴幅值实现单肢步长的控制。步态控制算法将运动稳定性、低能耗和运动速度作为主要考虑因素,通过判断可用落足点及机器人的姿态选择步态,提高机器人的运动速度。若地面存在可用trot步态的落足点且机器人姿态正常,则利用相对速度较快的trot步态行走;否则,采用 walk步态行走,以实现越障或姿态调整。
Other AbstractThe quadruped robot excels in locomotion on rough terrains locomotion because of its higher flexibility and better environment adaptability. The gait planning in complex environments becomes an active research in the field of robotics. Based on the central pattern generator, this research focuses on the gait planning of quadruped robots in confined environments. The main work is summarized as follows. The Hopf oscillator based central pattern generator, utilized in this research, can generate rhythmic control signals with different frequencies for the swing phase and the stance phase. Considering the phase anomaly caused by gait transition, a phase delay model is proposed by modifying the Hopf oscillator. The simulation results show that the quadruped locomotion is stable during gait transition. Aiming at passing through tight spaces with free-collision, an adjustment approach of the Center of Gravity is designed to achieve stable quadruped walking. The Center of Gravity is adjusted through the rhythmic medium value transition, which automatically generates smooth trajectories according to preset parameters. A rhythmic bias compensation method is proposed for maintaining the rhythmic medium positions of legs vertical to the ground to alleviate the bump caused by the body pitch. Meanwhile, an adjustment technique for the hip motion amplitude is developed to maintain the uniform motion when the robot posture changes. A gait planning method is developed for crossing planar obstacles. The method includes locomotion generation and gait planning. Locomotion generation is composed by the central pattern generator model based on the Holf oscillator to output the standard oscillation signals, and the motion amplitude adjustment for controllable oscillation amplitudes of the negative part and positive part. The gait planning algorithm outputs a sequence set of footholds that guarantees the stability and validity of the locomotion. To improve the locomotion speed, the strategy of gait pattern transition is adopted. Gait pattern is selected according to robot postures and available area. The performances of proposed methods have been verified on a simulated quadruped robot model and a real quadruped robot.
Other Identifier2011E8014661087
Document Type学位论文
Recommended Citation
GB/T 7714
吴限. 约束环境下的四足机器人步态规划[D]. 中国科学院自动化研究所. 中国科学院大学,2014.
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