【作者】 毛世鑫；

【导师】 杨杰； 董二宝；

【作者基本信息】 中国科学技术大学 ， 精密仪器及机械， 2014， 博士

【摘要】 通过千百万年的自然演变和优化选择,生物体获得了高效的运动能力和对环境的高度适应性。从海洋到大陆的过渡地带,存在着沙滩、礁岩、泥淖、乱石、沼泽等多种介质环境,仿照栖息于此的柔体动物结构特性及运动步态,研制出具有仿生结构的柔体机器人,探索其与自然环境良好的交互适应性及在多介质地形中的运动推进机理,以期在资源勘探、排险救援、环境监测、军事侦察等应用领域发挥重要作用。本文围绕多环境介质下辐射对称结构的柔体机器人推进机理及实现方法展开仿生运动学、柔性体建模分析、形状记忆合金(SMA)材料特性研究、柔体机器人制备方法、多模步态控制等一系列工作,主要研究内容及成果归纳如下：(1)辐射对称柔体仿生研究及两侧对称机器人探索。通过对典型辐射对称型动物深入调研分析,归纳出其基本结构特点及步态运动模式。参照深红海星仿生学参数,研制出辐射对称型柔体机器人,并选取了高功重比、变形大、易控制的SMA弹簧作为致动器以满足柔性大变形需求。在3D打印快速成型平台基础上,发展了仿生柔体机器人制备方法,不仅大大缩短了研制周期而且有效促进了仿生结构的改进优化。同时,以蜥蜴和乌龟为仿生对象,对具有连续型柔性足的两侧对称型机器人推进性能开展了初步的研究探索。由凸轮绳索机构驱动的机器人具备以三角步态、对角步态在草地等地形环境通过性能,为完全柔性的辐射对称型机器人多介质环境推进机理探索研究奠定了基础。(2)柔体机器人建模分析与SMA特性研究。归纳总结了柔性足常见的变形描述和建模方法,并对柔性足端工作空间进行初步建模。通过对两种辐射对称型柔体机器人单足综合性能的对比分析发现,在非水下环境中,采用非密封式SMA致动器内嵌驱动布置可使机器人获得更大的柔性变形和更快的动作响应。此外,将柔性足弯曲变形过程等效简化为平面悬臂梁的弯曲变形,进而建立起伪刚体模型,并给出自由末端位置求解的公式。通过Brayan修正D-H法建立了多足辐射对称柔体机器人的运动学模型,基于外部测量技术获得变形过程中驱动器长度与柔性足弯曲变形角度的对应变化关系。对SMA准静态热／力耦合特性和本构模型的研究探索,获取了SMA马氏体、奥氏体相变发生过程以及相变温度和相变热焓值,并观测到其不完全相变过程中所特有的“温度记忆”效应。同时,SMA弹簧的变位分析获取了柔体机器人控制所需的必备数据信息。(3)柔体机器人多模步态控制研究。借助于路径规划中广泛采用的人工势场法及其改进方法,重点开展了柔体机器人在固定障碍环境和移动障碍环境下朝目标点前进中的路径规划避障问题,并进行仿真验证。在辐射对称动物基本运动步态的归纳总结基础上,探讨了柔体机器人运动机理,给出了辐射对称型柔体机器人平坦地形爬行、越障、避障、滚动等步态的运动策略及控制模式。对中枢模式发生器(CPG)的生物学机制、控制模型进行了详尽的归纳总结,探讨了CPG节律产生的细胞机制以及其与动作执行系统的全局携带关系。同时,基于Wilson-Cowan模型开展五足辐射对称柔体机器人的CPG控制探索,进行了柔性足等幅等频变形和变幅变频变形的仿真实验,设计了柔性足弯曲运动的神经元估计器和仿生神经网络闭环控制系统。(4)多介质地形环境推进机理研究。描述了典型介质环境特性,并选取平地、沙地、乱石、泥地、障碍和岩石这六种介质开展五足辐射对称型柔体机器人推进性能实验,通过对应的仿生运动步态、控制策略、动作切换,机器人均可顺利穿行不同的地形环境到达目标位置。实验结果表明,五辐对称型柔体机器人具备完全的多介质环境协同推进及地形适应性能；同时,在固定时长内,机器人在沙地爬行的距离最远,其速度是在乱石环境下和平地爬行速度的6.5倍与2.2倍。此外,对机器人抵抗挤压变形和冲击性能测试结果也验证了其良好的鲁棒性。更进一步地,根据柔体动物形态学参数,研制了单足、三足、四足、五足和六足等五种足型的柔体机器人,来开展在多足型柔体机器人运动机理和推进性能探索,并得出了不同足数量的柔体机器人运动性能与其本体物理参数(质量、体长)之间的对应关系。实验结果表明六足型机器人在固定时长内具有最大的位移和平均运动步长,分别达到了251mm和20.8mm,体长较为接近的四足型和五足型机器人在相同地形条件下的运动性能较为接近,而单足型则和三足型机器人的运动性能比较接近。更多还原

【Abstract】 Animals possess efficient athletic ability and high adaptability to the environment through millions of years of natural evolution and optimization options. There is a variety of environmental media in the transition zone from the ocean to the continent, such as beach, reef, quagmire, rocks, swamps etc. Soft animals living in this zone are supplied with plentiful bionic structure and moving gaits for the development of soft robots. The bionic robot prototype is built to explore its interactive adaptability with natural environments and propulsion mechanism under multi-media, with a view to playing an important role in several applications, such as resource exploration, risk rescue, environmental monitoring, and military reconnaissance etc. This dissertation focuses on the propulsion mechanism and realization method of the radial symmetry soft robot under multiple environmental medias, including bionic kinematics, flexible body modeling and analysis, the material properties of shape memory alloy (SMA), manufacturing method for soft robot, multi-gait control etc. The main research contents and results are summarized as followings:(1) Bionic research on actinomorphic soft animals and exploration of bilaterally symmetrical robot. We summarized the basic structural features and gait patterns of typical radiation symmetrical animals via comprehensive investigations. The radial symmetry soft robot was constructed according to the bionic parameters of Fromia milleporella. The SMA spring worked as the actuator of the robot owing to its advantage of high power weight ratio, large deformation and easy control. The manufacturing method for soft bionic robot was developed on the basis of3D printing rapid prototyping platform, benefiting from which we not only greatly shorten the development cycle of a new robot but also effectively promote the improvement and optimization of biomimetic structures. Meanwhile, imitating the lizard and turtle, a bilaterally symmetrical robot with continuous limb was built to explore its propulsion mechanism. The robot actuated by cam-rope mechanism was able to pass through different terrain environment with tripod gait and diagonal gait, which prepared strong foundation for researching on the propulsion mechanism of radial symmetry robot.(2) Modeling and analysis of the soft robot and material properties of SMA. We summarized the common deformation description and modeling methods for soft limb, and preliminary modeling of the action space of soft limb tip. By comparing the comprehensive performance of two kinds of soft limbs, the unsealed design of soft limb allowed the robot to acquire larger deformation and faster action response. In addition, the pseudo-rigid-body model of soft limb could be built through simplifying its bending process as equal to bending process of cantilever in plane. The kinematics model of radial symmetry soft robot was built by the amended Brayan D-H method. The exploring study on the quasi-static thermo-mechanical coupling characteristics and constitutive model of SMA resulted in acquiring the temperature and enthalpy in martensite transformation and "temperature memory effect" in the SMA incomplete martensite-reverse-transformation process. Meanwhile, the deformation analysis of SMA spring prepared the basic information for the control of soft robot.(3) Research on multi-gait control of soft robot. The issue of path planning for avoidance of both static and dynamic obstacles was solved by the improved artificial potential field method, which was certified by simulation experiment. On the basis of the summary of basic moving gaits of radial symmetry animals, we discussed the mechanism of soft robot movement and presented the movement strategy and control mode for multi-gait, such as crawling, navigating, bypassing, rolling etc. the biological mechanisms and control model of central pattern generator (CPG) was discussed in this dissertation, including the cellular mechanisms for generating rhythmic. Meanwhile, the Wilson-Cowan CPG model was employed to control the radial symmetry soft robot. The motion estimator and neurons bionic neural network closed-loop control system were designed for the control of soft limb.(4) Study on the propulsion mechanism under multi-media environments. Six kinds of environmental media (e.g. flat ground, sand, rock, riprap, mud and rock) were selected for the experiments of propulsion performance of the radial symmetry soft robot. The robot prototype was able to reach the target positions with multi-gait in proposed environmental media via corresponding bionic gait, control strategy and motion changes. Experimental results showed that the actinomorphic robot possesses the performance of the cooperative propulsion and terrain adaptability. Meanwhile, within the fixed duration, the robot moved ahead on the sand with the most displacement, and its speed on the sand was6.5times of the speed on riprap ground and2.2times of flat ground. In addition, the test of extrusion resistance and impact resistance results also verified the robot’s good robustness. Furthermore, the soft robots with multi-limb (single limb, three limbs, four limbs, five limbs and six limbs) were designed according to the morphological parameters of soft animals for exploring their movement mechanism and propulsion performance. The relationship between the movement performance and the physical parameters (mass, body length) of multi-limb robot were obtained through many groups of experiments. The results showed that the six-limb robot acquired maximum displacement and average step length within the fixed duration, were up to251mm and20.8mm respectively. Five-limb robot and four-limb robot with similar body length showed approximate movement, and the same phenomenon between three-limb robot and one-limb robot.更多还原