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 biomi...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.展开更多
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 st...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.展开更多
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 mec...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.展开更多
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 s...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.展开更多
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 oxid...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.展开更多
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 o...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.展开更多
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 inse...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.展开更多
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 ...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.展开更多
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 (Ornithoct...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.展开更多
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...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.展开更多
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....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.展开更多
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 ...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.展开更多
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...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.展开更多
基金supported by the National Natural Science Foundation of China(Nos.51435008,51705247)the China Postdoctoral Science Foundation(No.2017M611802)
文摘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.
基金supported by the National Natural Science Foundation of China(Nos.31601870,51435008)Jiangsu Educational Innovation Program(No.KYLX16_0328)
文摘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.
基金supported by the Funding for Outstanding Doctoral Dissertation in Nanjing University of Aeronautics and Astronautics (BCXJ10-10)the National Hi-Tech Research & Development Program of China (2007AA04Z201)the National Natural Science Foundation of China (60910007, 50705043, 50975140 and 30700068)
文摘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.
基金This work was supported by the National Natural Science Foundation of China to Dai Z.D.(Grant No.60535020)Fund for Distinguished Young Scholar of China to Tong J.(Grant No.50025516)National Hi-tech Project(863 Project)to Dai Z.D.(Grant No.2002AA 423230).
基金Supported by the National High Technology Research and Development Program of China (Grant No. 2007AA04Z201)National Natural Science Foundation of China (Grant Nos. 60535020, 30700068 and 50705043)
文摘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.
基金Supported by the National Natural Key Science Foundation of China (Grant No. 60535020)National Natural Science Foundation of China (Grant Nos. 50705043 and 50805076)Natural Science Foundation of Jiangsu Province (Grant No. 2007202)
文摘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.
基金supported by the National Natural Science Foundation of China (Grant Nos.key project:50635030 and general project:50675160)Aviation Science Foundation of China (Grant No.2007ZA52008)
文摘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.
基金Supported by the National Natural Science Foundation of China (Grants Nos. 60535020, 50635030 and 50675160)the Development Plan of the State Key Fundamental Research (Grant No. 2007CB607600)
文摘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.
基金supported by the National Basic Research Program of China (2011CB302106)the National Natural Science Foundation of China (51175249,30770285)+1 种基金the Major Research Plan of the National Natural Science Foundation of China (90916021)the Jiangsu Natural Science Foundation (BK2009376)
文摘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.
基金supported by Funding for Outstanding Doctoral Dissertation in Nanjing University of Aeronautics and Astronautics (BCXJ10-10)the National Hi-Tech Research and Development Program of China (2007AA04Z201)the National Natural Science Foundation of China (60910007,31070344 and 50975140)
文摘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.
基金supported by the National High Technology Research and Development Program of China (2007AA04Z201)National Natural Science Foundation of China (60535020, 50635030, 30770285 and 30700068)
文摘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.
基金Supported by the National Natural Science Foundation of China (Grant Nos. 30400086, 30770285, 30700068)Key Project Program of National Natural Science Foundation of China (Grant No. 60535020)
文摘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.
基金supported by the National Natural Science Foundation of China (50705043, 50805076, 50975140)
文摘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.
基金supported by the National Natural Science Foundation of China (50805076, 60910007)Doctoral Fund of Ministry of Education of China (200802871043)Science Research Foundations of Nanjing University of Aeronautics & Astronautics (NS2010216, NS2012014)
文摘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.
