适应不同重力环境的仿壁虎机器人运动仿真

针对不同重力环境下仿壁虎机器人的运动稳定性、运动高效协调性等问题,基于四足机器人的步态规划现状和仿壁虎机器人自身特定的机械结构,设计了仿壁虎机器人在g、0、-g 3种环境下的足端轨迹和运动步态。在ADAMS仿真软件中研究了机器人的运动学和动力学特性,得到了仿壁虎机器人稳定爬行与脚掌黏附力、足端轨迹和运动步态的关系。探讨了仿真结果的合理性和局限性,为仿壁虎机器人在实际环境中的稳定运动奠定了理论基础。

一种面向航天需求的仿生柔性机械臂的设计

针对航天器舱内环境的障避实际需求,基于自然界象鼻的内部肌肉结构分布特点,设计一种多冗余自由度仿生柔性机械臂。该机械臂由8个柔性关节组成,每个柔性关节具有3个自由度,相比传统机械臂,具有结构紧凑、刚度较高、运动灵活、操作空间广泛等特点。针对所提出的单个柔性关节与多个关节组成的仿生柔性机械臂进行运动学建模分析。利用制作的仿生柔性机械臂,进行航天避障任务试验,验证了该机械臂结构的可行性。

独立以来印度公共债务可持续性实证研究

在全球债务持续攀升、经济运行风险日趋加大的背景下,采用动态债务方程对独立以来印度总体公共债务和外债的可持续性进行研究。结果表明,无论是总体债务还是外债,印度债务的可持续性欠佳。对印度来说,政府加强短期和中长期债务管理已刻不容缓;对中国政府而言,借鉴印度债务管理经验或教训是非常必要的;在"一带一路"背景下,赴印投资的中资企业应在项目选择、财务管理、风险压力测试和预警等方面做好债务风险的防范。

基于三目视觉的模块化弧焊机器人焊接作业自动标定算法研究

为解决模块化弧焊机器人焊接作业标定误差高的缺陷,实现焊接作业的智能化及自动化,研究基于三目视觉的模块化弧焊机器人焊接作业自动标定算法。建立包含三目视觉摄像机的模块化弧焊机器人模型,分析三目视觉摄像机中三个相机的位置关系,建立带约束的多目标优化方程;利用正交平面工件标定法,通过调整机器人坐标系与实际作业环境内工件的匹配位姿,实现工件自动标定。实验结果表明,该算法可实现模块化弧焊机器人焊接作业自动标定,三目视觉摄像机标定的相对误差低于0.1 mm,绝对误差低于0.2%,焊接作业工件标定的均方根误差低于0.6,说明该算法自动标定的误差低,精度高,实现了焊接作业的智能化及自动化。

Adhesion Property of Vertically Aligned Carbon Nanotubes Under High Temperature

Because of having millions of well vertically aligned hairs on their feet,geckos can fluently walk on the vertical walls and even ceilings.Vertically aligned carbon nanotube(VACNT)array has been widely used as a biomimetic adhesive due to the structural and functional similarity with gecko's foot hairs.Besides,the advanced properties of VACNT make it a prominent functional adhesive.In this paper,the dry adhesion of VACNT array under the temperature range of 25—150℃is studied.Because of the intrinsic excellent thermal resistance,VACNT array shows great adhesion under high temperature.When the temperature changes from 25℃to 150℃,the shear adhesive strength of VACNT array deceases from 12.04 N/cm^2 to 6.08 N/cm^2.Though there is a 50 percent decrease,the adhesive strength of 6.08 N/cm^2 is still remarkable for dry adhesive materials.The VACNT's micro structures are analyzed by SEM and the adhesion change phenomenon is interpreted in theory.We believe that the robust high temperature adaptation of VACNT dry adhesive can be used in many extreme environments,such as aerospace application.

Design of a Foot-End Three-Axis Force Sensing Module for Gecko-Like Robot

The problems of attachment failure and detachment impact within gecko-like robots’ locomotion control are considered in this paper. A real-time foot-end force intelligent sensing module with integrated sensing and structure is developed to help the robot get the foot-end force information in time and realize stable locomotion in an uncertain environment. Firstly,a structure/sensing integrated elastomer based on a Maltese cross/cantilever beam structure is completed by designing and finite element analysis. Secondly,a real-time data acquisition and transmission system is designed to obtain the foot-end reaction force which is miniaturized and distributed. Thirdly,based on this system,a force sensor calibration platform is built to complete the calibration,decoupling,and performance testing of the sensing module. Finally,the experiment of single-leg attachment performance is carried out. The results indicate that the three-axis sensing module can detect robot’s weight,measure the reaction force with high precision and provide real-time force from robot’s foot end.

滚轮黏附式爬壁机器人的附着机理及应用试验研究

壁虎依靠脚掌上的纳米级刚毛,可以附着在光滑的壁面甚至天花板上,并且可以以较快的速度自如爬行。以分子间作用力为附着机制的仿壁虎黏附爬壁机器人,在军事和民生领域都有非常迫切和广阔的应用需求。壁虎在壁面爬行时,足端斜向上运动带动脚趾以一定角度旋转脱离接触面,以这种稳黏附、易脱附的爬壁机制为启示,设计了一种滚轮黏附式的仿生爬壁机器人。开展了机器人爬壁状态下的力学原理分析,得到了电机扭矩、机器人自重与黏附力的关系。在采用电机驱动、齿轮传动的四驱结构的基础上,设计了稳黏附、易剥离的四辐条滚轮机构,实现了轮式机器人在光滑壁面的爬行。通过拍摄并分析机器人爬壁的高速视频,得到了机器人爬壁的启动加速度和稳定后的爬行速度。为了进一步测试分析机器人爬行于不同倾角平面时黏附力的变化范围及变化规律,设计了精度为3 mN的二维力传感测试平台,验证了仿壁虎机器人轮式黏附垫的黏附性能,结果显示研制的滚轮黏附式爬壁机器人可以在光滑垂直壁面上实现快速稳定地爬行。

Behavior and dynamics of gecko’s locomotion:The effects of moving directions on a vertical surface

The study of the movement behavior of geckos on a vertical surface, including the measurement and recording of the reaction forces as they move in different directions, plays an important role in understanding the mechanics of the animals' locomotion. This study provides inspiration for the design of a control system for a bionics robot. The three-dimensional reaction forces of vertical surface-climbing geckos (Gekko gecko) were measured using a three-dimensional force-sensors-array. The behavior of gecko as it moved on a vertical surface was recorded with a high speed camera at 215 fps and the function of each foot of a gecko are discussed in this paper. The results showed that the gecko increased its velocity of movement mainly by increasing the stride frequency in the upward, downward and leftward direction and that the speed had no significant relationship to the attachment and detachment times. The feet above the center-of-mass play a key role in supporting the body, driving locomotion and balancing overturning etc. The movement behavior and foot function of geckos change correspondingly for different conditions, which results in safe and effective free vertical locomotion. This research will be helpful in designing gecko-like robots including the selection of gait planning and its control.

Researches and developments of biomimetics in tribology

动物和植物开发了有通过 10 亿年和变得的模型 fortribological 的进化的优秀 tribologicalcharacteristics 的质地设计的最佳的几何结构，聪明的拓扑的材料和多功能的表面。这篇论文提出简历的定义和臀部模仿的摩擦学，调查地位液体固体接口自我清洗，在动物之间的粘附“脚和固体出现，穿模仿的设计和液体固体上的仿生的设计连接的生物表面和简历的特征。tribologicalbiomimetics 的进一步的开发被讨论。

Angular observation of joints of geckos moving on horizontal and vertical surfaces

Because of their outstanding climbing and motor coordination ability, geckos have provided the basis for a peculiar bionic model leading to the development of a geckorobot. A three-dimensional locomotion observation system was constructed to measure angular orientations of joints while geckos trotted (337.1 mm/s) and walked (66.7 mm/s) on horizontal surfaces, and trotted (241.5mm/s) and walked (30.6mm/s) on vertical surfaces. Moving over horizontal surfaces, the joints rotated more quickly the greater the speed, and the swinging scope of forelimbs stayed nearly at 59 degrees when swinging forward, but extended from 72 degrees to 79.2 degrees when swinging backward. The lifting angle of forelimbs was always positive to keep the center of mass close to the surface when moving up vertical surfaces, the scope of the forward swinging forelimbs forward extended from 33.7 degrees to 36.7 degrees with increasing speed, while the scope of backward swinging forelimbs remained almost the same at 87.5 degrees. Alternative gaits had little effect on the swing angle of hindlimbs of the geckos moving on both horizontal and vertical surfaces.

Hybrids perfluorosulfonic acid ionomer and silicon oxide membrane for application in ion-exchange polymer-metal composite actuators

This paper reports a new technique to fabricate an ion-exchange polymer-metal composite (IPMC) actuator. This technique is based on a hybrid organic-inorganic composite membrane. In the fabrication course, silica oxide particles, prepared from hydrolysis of tetraethyl orthosilicate in situ with sol-gel reaction, co-crystallize with perfluorosulfonate acid (PFSA) ionomer. Attenuated total reflectance fourier transform infrared spectroscopy (ATR-FTIR) analyses demonstrate that a highly water-saving hybrid membrane is formed. Measurements of mechanical properties reveal that elastic modulus and hardness of the hybrid membrane are about 2 times compared to a commercial PFSA membrane. Scanning electron microscopy (SEM) results show that the hybrid membrane has a high porosity. Inside the membrane pores, there exists a great quantity of micro scale channels in the range of 100―300 nm. After fabrication of IPMC actuator, an electric current sensor, a force sensor, and a high speed camera are assembled and used to evaluate IPMC performance. It is shown that, compared to an IPMC actuator made from a commercial membrane, the electromechanical performance of the new actuator increases 6―8 times; when it is actuated in air, its stable non-water working time is prolonged for 6―7 times.

Morphology and mechanical properties of Cybister elytra

The mechanical properties and the topological structure of cross-sections found in Cybister elytra are presented.SEM images show the similar geometric structure in transverse and longitudinal sections.Elytra consist of several layers:a dense,black epicuticle,an exocuticle that is braided by several parallel chitin fiber layers in a helix structure,and many bridge piers formed by the fiber bundles that connect the exocuticle to the endodermis,forming a composite,light-weight biomaterial.The mechanical properties along the edge of elytra are measured using a nano-indenter.The hardness and modulus of fresh cybister elytra is 0.31 GPa and 6.13 GPa,respectively.The ultimate stresses of fresh elytra,measured by using a tensile test machine,are 169.2 MPa and 194.5 MPa in the transverse and longitudinal directions,respectively,which is twice higher than that of the dried one.The difference in the two directions indicates that this bio-material has been topologically optimized during evolution.The results may provide a biological template to inspire lightweight structure design for aerospace engineering.

Structural design inspired by beetle elytra and its mechanical properties

On the basis of the microstructure of the cross-section of a beetle's elytra,three bio-inspired lightweight structures were designed and built from acrylonitrile butadiene styrene plastic with a three-dimensional printer.The mechanical properties of three lightweight structures were analyzed and compared employing the finite element method,and quasi-static compression experiments and a three-point bending test on the structure samples were carried out using an electronic universal testing machine to verify the effectiveness of the finite element method.The results show that all three bio-structures were lightweight and had excellent mechanical properties.In particular,the bio-structure with spherical holes and hollow columns perpendicular to the top and bottom surfaces best imitated the microstructure of the cross-section of the Cybister elytra and had the greatest specific strength/stiffness in compression and bending.Finally,a preliminary optimization design was obtained for this bio-structure to further improve its specific strength and specific stiffness to 31.82 kN m/kg and 108.73 kN m 2 /kg respectively.

Contact mechanics of pad of grasshopper (Insecta:ORTHOPTERA) by finite element methods

During locomotion, insect feet endure dramatic impact force and generate adhesive force which is controlled by the architecture of the foot. The patterns of smooth attachment pads in insect feet vary widely among insect orders and families. The functional significance of the micro-structure and geometric design of insect feet remains largely unknown. In this study, we developed a two-dimensional finite element model of a grasshopper's attachment pad. Realistic geometric microstructure and material properties are applied in the biomechanical analysis of the structural behavior during contact. Here we use scanning electronic microscopy to study the microstructure of the grasshopper's pad, and then use the finite element method to calculate the deformation vector fields, contact stiffness, contact area, function of the airbag and strain fields during the contact process. The results reveal that the geometric design and material topology of a grasshopper's pads are very effective in reducing contact stiffness, increasing contact area and generating high friction force during the contact procedure. The rod-containing structure supporting the soft exocuticle makes the pads highly adaptive to various surfaces and decreases the stress inside the pads.

Movement behavior of a spider on a horizontal surface

Studying the locomotive behavior of animals has the potential to inspire the design of the mechanism and gait patterns of robots ("bio-inspired robots"). The kinematics characteristics of a spider (Ornithoctonus huwena), including movement of the legs, movement of the center of mass (COM) and joint-rotation angle, were obtained from the observation of locomotion behaviors recorded by a three-dimensional locomotion observation system. Our results showed that one set of the stance phase consists of four legs, which were leg-1 and leg-3 on one side and leg-2 and leg-4 on the other side. Additionally, two sets of the stance phase comprised eight legs alternately supporting and driving the motion of the spider's body. The spider primarily increased its movement velocity by increasing stride frequency. In comparison to other insects, the spider, O. huwena, has superior movement stability. The velocity and height of COM periodically fluctuated during movement, reaching a maximum during alternation of leg phase, and falling to a minimum in the steady stance phase. The small change in deflection angle of the hind-leg was effective in driving locomotion, whereas each joint-rotation angle of the fore-leg changed irregularly during locomotion. This research will help in the design of bio-inspired robots, including the selection of gait planning and its control.

Locomotion behavior and dynamics of geckos freely moving on the ceiling

To understand the mechanical interactions when geckos move on ceiling and to obtain an inspiration on the controlling strategy of gecko-like robot,we measured the ceiling reaction force(CRF) of freely moving geckos on ceiling substrate by a 3-dimensional force measuring array and simultaneously recorded the locomotion behaviors by a high speed camera.CRF and the preload force(FP) generated by the geckos were obtained and the functions and the differences between forces generated by fore-and hind-feet were discussed.The results showed that the speed of gecko moving on the ceiling was 0.17-0.48 m/s,all of the fore-and hind-legs pulled toward the body center.When geckos attached on the ceiling incipiently,the feet generated a very small incipient FP and this fine FP could bring about enough adhesive normal force and tangential force to make the gecko moving on ceiling safely.The FP of the fore-feet is larger than that of the hind-feet.The lateral CRF of the fore-feet is almost the same as that of the hind-feet's.The fore-aft CRF generated by the fore-feet directed to the motion direction and drove their locomotion,but the force generated by the hind-feet directed against the motion direction.The normal CRF of fore-and hind-feet accounted for 73.4% and 60.6% of the body weight respectively.Measurements show that the fore-aft CRF is obviously lager than the lateral and normal CRF and plays a major role in promoting the fore-feet,while the hind-feet of the main role are to provide a smooth movement.The results indicate that due to the differences of the locomotion function of each foot between different surfaces,the gecko can freely move on ceiling surfaces,which inspires the structure designing,gait planning and control developing for gecko-like robot.

Divisional and hierarchical innervations of G. gecko's toes to motion and reception

As a member of robot families, climbing robots have become one of the research hot-spots in the robotic field recently and Gekko gecko (G. gecko) has been broadly seen as an ideal model for climbing robot development. But for gecko-mimic robots, one of the key problems is how to design the robot's foot. In this paper, (1) high-speed camera recording and electrophysiological method are used to observe motion patterns of G. gecko's foot when it climbs on different oriented surfaces; (2) nerve innervations of gecko's toes to motion and reception are studied. It is found that the five toes of the G. gecko can be divided into two motion and reception divisions, and also its motion and reception are modulated and controlled hierarchically. The results provide important information and exclusive ideas for the foot design and control algorithm of gecko-mimic robots.

Force optimization of ionic polymer metal composite actuators by an orthogonal array method

Ionic polymer metal composites (IPMCs), a new kind of electro-active polymer, can be used for micro robotic actuators, artificial muscles and dynamic sensors. However, IPMC actuators have the major drawbacks of a low generative blocking force and dependence on a humid environment, which limit their further application. Multiple process parameters for the fabrication of IPMCs were optimized to produce a maximum blocking force; the parameters included reducing agent concentration, platinum salt concentration in the initial compositing process, and tetraethyl orthosilicate (TEOS) content. An orthogonal array method was designed and a series of fabrication experiments were carried out to identify the optimum process parameters. The results show that the platinum salt concentration in the initial compositing process plays the most significant role in improving the blocking force of IPMCs, the TEOS content plays an important role, and the reducing agent concentration has no apparent effect on the blocking force. In the optimized conditions, the IPMC actuator exhibited maximum blocking force of 50 mN, and the corresponding displacement was 14 mm. Compared with normal conditions, the blocking force improved 2.4-fold without sacrificing the displacement, and the effective air-operating life was prolonged 5.8-fold for the blocking force and 5-fold for the displacement. This study lays a solid foundation for further applications of IPMCs.

Fabrication and adhesion of hierarchical micro-seta

Spark-erosion perforating technology was used to fabricate a Cu-based template characterized by pores with radius of 0.5 mm inclined at 75°. A commercial silicone elastomer of poly(dimethylsiloxane) (PDMS) with a rich Si-H content was used to produce an inclined array of primary setae. The technique of argon ion plasma etching on crystalline silicon was used to fabricate negative templates with radii of 5, 10, and 20 μm. The Si-H rich PDMS was used to cast three types of fine array templates, which acted as the secondary setae. A vinyl-rich PDMS precursor was used to bind the primary and secondary setae by a hydrosilylation reaction, thus allowing the formation of three different hierarchical arrangements of setae. Adhesion tests demonstrated that shear adhesion was anisotropic, first increasing in strength then decreasing to a stable level as slippage occurred. The adhesion strength was significantly influenced by the nature of the secondary setae, showing a strong correlation with aspect-ratio and concentration.

A stereotaxic method and apparatus for the Gekko gecko

To study the modulation mechanism of the middle brain of the Gekko to the locomotion, we introduced a stereotaxic method first in literature and developed an apparatus suitable for Gekko gecko, the big-gest wall and ceiling climber in nature. We defined the bregma and nasal points as reference points, selected the bilateral infraorbital margin and top point of the maxillary tooth for locating and fixing, and set up the line passing through the bregma and paralleling to a line connecting the bilateral infraorbital margin as x axis. Then, we defined a horizontal plane in the stereotaxic instrument, passing through x axis and the certain point which is 4.8 mm exactly above the nasal point, as the XOY plane; the sagittal plane, i.e. the YOZ plane, is the plane which is perpendicular to x axis and passes through the bregma; the plane, i.e. the XOZ plane, which passes through x axis and is perpendicular to the horizontal plane is the coronal plane. We designed a set of head holder which includes three parts: bilateral infraorbital margin clamps, a gecko adaptor holding the rostral side of the upper jaw. The allocation and operation of the head holder is accurate and simple, and the device is low in cost and compatible with standard stereotaxic instrument.