【作者】 张琰；

【导师】 任露泉；

【作者基本信息】 吉林大学 ， 仿生科学与工程， 2011， 博士

【摘要】 蝼蛄是一种有着优异挖掘能力的昆虫。在高度适应土中生存的同时,蝼蛄还具备一定的地表活动能力、飞行能力和凫水能力,具有多栖性。对动物多栖性能的研究不仅是动物行为学领域的研究热点,同时也可为工程仿生学中机器人在多环境下的“兼容”设计提供重要的生物学基础。对蝼蛄地下挖掘和陆地行走的运动学规律与机理的研究,可为挖掘式多足机器人的设计提供仿生原型。同时,蝼蛄优异的挖掘功能也可为提高触土部件切削能力和提高使用寿命的改进设计提供仿生学依据,具有重要的理论价值和应用前景。本文利用耦合仿生的研究思想,对蝼蛄的静态与动态耦合特性分别进行了定性、半定量与定量的分析,多角度分析了东方蝼蛄产生优异的环境适应性、体表耐磨特性、挖掘能力的生物耦合原理。在对蝼蛄的运动学研究基础上,建立了蝼蛄运动学物理模型及位姿方程,并对具有优良切削性能的爪趾构形进行了功能仿生。论文利用体视显微镜、扫描电子显微镜、透射电子显微镜、电感耦合等离子体原子发射光谱仪等多种测试仪器,分别对蝼蛄前足、前胸、前翅这三个主要触土部位的表面微观形态、组织结构、材料构成等耦元进行了生物信息采集及分析,并对其在挖掘运动中耐磨功能的实现机理,即静态耦合特性进行了分析。结果表明,东方蝼蛄系统中,前足、前胸、前翅可分别看做独立的、与土壤作用方式不同的静态耦合。此三个耦合在系统中以方位关系有机组合,东方蝼蛄耐磨功能的实现模式是“组合式非完全均衡并行实现”。利用高速摄像机,结合自制装置及类土壤介质,采集了蝼蛄在透明介质中前足的运动过程。结果表明,在类土壤介质中,前足产生向外的伸展和收回运动,在一个周期内,这两个运动的轨迹形成一个闭合空间,空间的大小取决于收回幅度的大小,在多数连续周期中呈现左大右小,左小右大的交替规律,且这种交替规律与胸腹关节的左右摆动有关。在挖掘运动中,前足挖掘动作的伸展频率大于后足的伸展频率。后足的伸展取决于前足挖掘前进距离的大小。中足在狭小的洞穴中起到旋转身体的作用,用以改变前足的工作平面。蝼蛄挖掘过程中,前足、中足、后足及胸腹关节处于身体不同的部位,在运动中与土壤间的作用方式不同,三者以“复合式非完全均衡并行实现模式”实现挖掘功能。静态耦合是动态耦合的物质基础,动态耦合的作用结果与挖掘功能的实现紧密相关。利用与三维运动信息采集系统,分别采集了完整蝼蛄在地面上的行走运动及缺少前足、中足、后足的蝼蛄附肢运动。在对运动学数据提取分析的基础上,统计了蝼蛄在一个周期内,前足、中足、后足各腿节的角度变化趋势,统计了一个周期内蝼蛄身体左右摆动及上下俯仰的角度变化。对地面行走时的步态及行走规律进行分析,对比了去除足的蝼蛄与完整蝼蛄在步态、各足工作系数、关节运动角度的变化及身体摆动和俯仰的角度变化等运动参数上的异同。结果表明,蝼蛄在地面上的运动分为两个部分：附肢(足)的运动和躯干的运动。附肢的运动包含三对足的配合运动；躯干的运动包含俯仰、偏转甚至滚动。蝼蛄前足的作用不像普通六足昆虫一样重要,不能起到引导转向的作用,仅限于辅助其它两足更好地发挥各自的功能,具有较小的支撑和拖拽作用。蝼蛄中足在地面运动时起到比普通陆地昆虫更大的作用,具有辅助后足向前推动身体、保持身体稳定及支撑的作用,且能够替代前足,与身体摆动相配合,有效实现控制行走方向、灵活转弯的功能。蝼蛄的后足在地面运动中为身体提供主要的向前推动力,同时能够支撑身体。被去除的足通常对与其相邻的足影响较大,且受到影响的足上,股-胫节的变化最为明显。前足的去除对蝼蛄的迈步频率、行走速度影响不大,且对另外两对足的步态序列没有产生影响,从侧面证明,前足在行走中只起到较小作用。中足会由于前足的缺失减小关节的伸展,增大关节角度的变化幅度。去除中足后,蝼蛄的前足与后足同时受到影响,前足关节的伸展和收缩幅度变大,用于产生更大的拖拽功能；后足的角度变化规律因身体左右失去平衡而打乱。去除后足后,与肢体完整的蝼蛄相比,前足关节参数基本不变,中足因代偿了后足的推动作用,产生了不同的运动规律,表现为关节角度变化的截然不同。总之,中足和后足在行走时代偿了前足的大部分功能,可将前足从行走中释放出来,用于挖掘。对蝼蛄质心与附肢的能量进行了计算,比较了蝼蛄与蟑螂及其它两足与四足动物的能量。蝼蛄质心机械能的计算结果与蟑螂相同,但足的动能占总机械能的比值远小于蟑螂,表明其在地面上的运动及耗能方式有别于普通陆地昆虫。在针对蝼蛄生物学研究基础上建立的蝼蛄运动系统物理模型中,每条足有3个旋转自由度,头胸部与腹部之间有2个旋转自由度。利用D-H法,以质心为全局坐标系,建立蝼蛄足末端在全局坐标系下的位姿方程,可为仿生机器人的动态模拟及设计提供运动学与机械学的理论基础。蝼蛄的爪趾具有良好的切削性能,以JL80斗齿为原型,利用蝼蛄爪趾的构形,即侧面轮廓线,设计了仿生斗齿,并采用快速成型设备制造出仿生斗齿试件。楔土试验表明,在反铲式挖掘机工况下楔入角为90°和60°时,仿生斗齿的楔入阻力均小于JL80原型斗齿。采用有限元分析软件ANSYS对仿生斗齿和JL80斗齿以60°和90°楔入角楔入土壤时的受力情况进行了数值模拟与分析,模拟试验结果与实际试验一致。模拟试验得出的受力云图表明,在楔入时,仿生斗齿可将对土壤的压力分散,使部分作用力由指向土壤下层改在土壤表层释放,从而减小楔入时的阻力。对JL80斗齿和仿生斗齿楔土的受力分析表明,仿生斗齿可在不改变挖掘机设计与工况的条件下,减小切削角,从而减小斗齿受到的总阻力在水平方向上的分量,进而减小切削阻力。更多还原

【Abstract】 The mole cricket is a typical soil-dwelling insect which has excellent abilities of digging and excavation. As mole cricket has high degree of adaptability in soil-environment, meanwhile, it has capabilities of moving on ground, flying and swimming, which shows a typical triphibian features. The studies of the habits and characteristics on triphibian insects are hotspots not only in academe, but also can provide the bionic theory foundation for the design of compatibility of the multi-environmental robot. The researches on the mechanism and pattern of the excavating motion and terrestrial locomotion can serve as a prototype for the design of multi-legged excavating robot. Moreover, the fore leg of mole cricket has developed into an effective digging organ, the study of that can offer a new insight into the design and improvement on excavating machinery.By taking the theory of biological coupling as theoretical guidance, this study applied quantitative, qualitative and semi-quantitative analysis methods to investigate the dynamic and static coupling characteristics of mole cricket, and made relatively comprehensive analysis to the reasons of why mole crickets have the unique adaptability to the soil-environment, wearable body surface and the ability of excavation. The kinematics-based physical model and the location-gesture equation were established based on the kinematics experiment results. Moreover, with the purpose of engineering applications, the geometrical configuration of fore leg claw was studied, which has excellent excavating performance.The biology information, which include microstructure, tissue structure, and material composition, of mole crickets’ main soil-engaging components (fore leg, prothorax, and fore wing) were acquired by using the stereo microscope, scanning electron microscope, transmission electron microscope, and inductively coupled plasma atomic emission spectrometer. By using this information, the implementing mechanism of wearable ability in excavating motion, i.e. the static coupling characteristics, was analyzed. The results show that the fore leg, prothorax and fore wing of mole cricket can be respectively considered as independent coupling system which has different interaction with soil. In the coupling system of mole cricket, these three subsystem assembled by direction and position relationship, and the implementing pattern of wearable ability is’combined parallel implementation of incomplete equilibrium’.By using the high speed camera and combining with homemade experimental facility and soil’s resemblance, the movement course of fore leg in mole crickets were acquired. The results show that the movements of fore leg are composed of a series of stretch and fold actions in digging process. In a specific cycle, the motion trajectories of a stretch and a fold action form a closed loop which area depends on the extent amplitude of the fold action. In majority of sequential cycles, the areas of the loops are alternately changed, which has the relationship with the swing of thorax-abdomen joint. In excavation, motion frequencies of fore legs are bigger than that of middle and the hind legs, the movements of hind legs depend on the distance body moved forward, and the function of the middle leg is to help the body roll so as to switch the working face.In the coupling system of a digging mole cricket, the interactions between the three pair of legs and soil are diverse from each other. The implementing pattern of digging function is ’compound parallel implementation of incomplete equilibrium’. In conclusion, the static coupling is the material foundation of dynamic coupling which can greatly influence the implementation of digging function.By using a high speed 3D video recording system, a series of kinematics tests on terrestrial walking mole crickets were carried out, in which the three-dimensional kinematics information and parameters of healthy and disabled mole cricket were recorded and analyzed respectively, including amputated fore leg, amputated middle leg and amputated hind leg. According to the kinematics parameters, the joint angles of three pair of legs and the pitch, yaw, and roll angle of body were calculated respectively. The change patterns of these angles were discussed. By comparing the kinematics parameters of mole cricket with amputated legs and integrity one, the differences on gait pattern, duty factor, joint angles and body angles were investigated. The results shown that the terrestrial locomotion of mole cricket contains two discrete parts:appendage movement and trunk movement, i.e. the cooperation between three pair of legs and body rotation (pitch, yaw and roll), respectively.According to the results, we can conclude that, during terrestrial locomotion, the fore legs of mole cricket only have the small function of dragging and bracing instead of direction control in contrast with common hexapod insects. The results show that the middle legs of mole cricket do play a more important role than common hexapod insects in guiding direction. When terrestrial walking and turning, the middle legs and body joint act more effective in direction control and body support which compensate the function of fore legs partly, and the hind leg play the roles of pushing body forward and supporting the trunk.Generally, the amputation of a pair of leg has certain influence on movement of the adjoining leg, especially on angular variation of the femur-tibia joints. The results show that the amputation of fore leg has minor influence on stride frequency and forward velocity, has less influence on the gait sequence of middle and hind leg, which indirectly proved that the main role of fore leg is not walking. After the amputation of fore legs, the extent of stretch of middle legs were decreased, meanwhile the range of joint angular was increased. After the amputation of middle legs, the motions of fore and hind legs were affected simultaneously, in which the movement range of fore legs increase in order to produce more drag force, and the movement pattern of hind legs was disturbed due to the instability of trunk. After the amputation of hind legs, by comparing with the healthy mole crickets, the parameters of joint angle change little in fore legs, and change a lot in middle legs which because the middle legs partly compensate for the function of hind legs. In conclusion, comparing with other common terrestrial insects, the middle and hind legs of mole cricket compensate some functions of fore legs which can relieve the fore legs from walking for digging or excavating.The kinematics-based physical model was established based on the results of kinematics study, in which every leg has three rotational degrees of freedom and head-abdomen part has two rotational degrees of freedom. By reference to the D-H method, the center of mass was chosen as original point of the global coordinate system, and the location-gesture of the end point of each leg equation was established, which provide the theoretical foundation for the design of bionic digging robot in kinematics and mechanics.Mole cricket’s claws have good characteristics in digging soil. By applying the geometrical shape of the claw of mole cricket to a conventional scale of JL80 excavator bucket teeth, bionic excavator tooth was designed. The models of bionic teeth and JL80 teeth were manufactured by using FDM-Dimension rapid molding system. The results of excavating test show that the resistance of bionic teeth is smaller than JL80 conventional teeth when the wedge angles are 90°and 60°. The internal stress of tooth and soil was simulated and analyzed by using finite element method with ANSYS software. The simulating results are in consistent with the practical experimental results. According to the stress contour, we know that bionic tooth can change the stress concentration place from the tip of tooth to the surface of soil, which can disperse the stress of the soil in order to decrease the resistance of wedging. By analyzing and comparing the stress of JL80 and bionic tooth in wedging process, it is clear that the bionic tooth can decrease the wedge angle by not change the design of excavator machine and the working condition. The horizontal component of the total resistance acting in bionic tooth can be reduced by decreasing the wedge angle, which devote to the decreasing of wedge resistance.更多还原