A Point-Wise Model of Adhesion Suitable for Real-Time Applications of Bio-Inspired Climbing Robots

Bio-inspired climbing robots relying on adhesion systems are believed to become essential tools for several industrial applications in the near future. In recent years, research has mainly focused on modeling micro-scale adhesion phenomena; a macro-scale adhesion model has however to be developed for the design of macro-scale systems. In this paper a macro-model of adhesion suitable for real-time applications is presented; it relies on a continuous representation of adhesion. An extension of the von Mises criterion is proposed as failure adhesion criterion in order to estimate the occurrence of detachment at any point of the contacting surface. An experimental set up has been designed in order to define the parameters of the model. A semi-automatic process has been developed to ensure repeatability and accuracy of the results. Polydimethylsiloxane (PDMS), which has revealed promising adhesive features for robotic use, has been used during the experimental phase. The macro-model of adhesion has been implemented in a multi-body dynamics environment based on Open Dynamics Engine (ODE) to simulate a spider-inspired robot. Simulations based on this model are suitable to represent the behaviour of climbing robots and also to optimize their design.     

Multi-Scale Compliant Foot Designs and Fabrication for Use with a Spider-Inspired Climbing Robot

Climbing robots are of potential use for surveillance, inspection and exploration in different environments. In particular, the use of climbing robots for space exploration can allow scientists to explore environments too challenging for traditional wheeled designs. To adhere to surfaces, biomimetic dry adhesives based on gecko feet have been proposed. These biomimetic dry adhesives work by using multi-scale compliant mechanisms to make intimate contact with different surfaces and adhere by using Van der Waals forces. Fabrication of these adhesives has frequently been challenging however, due to the difficulty in combining macro, micro and nanoscale compliance. We present an all polymer foot design for use with a hexapod climbing robot and a fabrication method to improve reliability and yield. A high strength, low-modulus silicone, TC-5005, is used to form the foot base and microscale fibres in one piece by using a two part mold. A macroscale foot design is produced using a 3D printer to produce a base mold, while lithographic definition of microscale fibres in a thick photoresist forms the ＇hairs＇ of the polymer foot. The adhesion of the silicone fibres by themselves or attached to the macro foot is examined to determine best strategies for placement and removal of feet to maximize adhesion. Results demonstrate the successful integration of micro and macro compliant feet for use in climbing on a variety of surfaces.     

Kinematic Analysis and Experimental Verification on the Locomotion of Gecko

This paper presents a kinematic analysis of the locomotion of a gecko,and experimental verification of the kinematicmodel.Kinematic analysis is important for parameter design,dynamic analysis,and optimization in biomimetic robot research.The proposed kinematic analysis can simulate,without iteration,the locomotion of gecko satisfying the constraint conditionsthat maintain the position of the contacted feet on the surface.So the method has an advantage for analyzing the climbing motionof the quadruped mechanism in a real time application.The kinematic model of a gecko consists of four legs based on 7-degreesof freedom spherical-revolute-spherical joints and two revolute joints in the waist.The motion of the kinematic model issimulated based on measurement data of each joint.The motion of the kinematic model simulates the investigated real gecko’smotion by using the experimental results.The analysis solves the forward kinematics by considering the model as a combinationof closed and open serial mechanisms under the condition that maintains the contact positions of the attached feet on the ground.The motions of each joint are validated by comparing with the experimental results.In addition to the measured gait,three othergaits are simulated based on the kinematic model.The maximum strides of each gait are calculated by workspace analysis.Theresult can be used in biomimetic robot design and motion planning.     

中药材蛤蚧的特异性PCR鉴定

以线粒体Cytb、COI、12SrRNA、16SrRNA基因序列为基础,探讨特异性PCR技术鉴定蛤蚧及伪品的可行性。本研究以所扩增的16条COI序列为引物设计依据序列设计了1对位点特异性引物COISF,COISR,同时从Gen-Bank上下载30条序列,设计了CytbSF,CytbSR;16S rRNASF,16S rRNASR;12S rRNASF,12S rRNASR另外3对位点特异性引物,因此共用4对位点特异性引物分别扩增蛤蚧及伪品实验样本。结果表明在复性温度为65℃时,4对引物都出现了理想的结果,即蛤蚧正品出现了扩增条带,而伪品没有扩增条带。同时对市售的蛤蚧商品进行了检测,在所供的7号标本中,有4号为蛤蚧正品,其余3号为蛤蚧伪品。本研究所设计的位点特异性引物可快捷、准确的鉴定蛤蚧及伪品,且在药检工作中具有极大的应用前景。     

Effects of Pendular Waist on Gecko's Climbing: Dynamic Gait,Analytical Model and Bio-inspired Robot

Most quadruped reptiles,such as lizards,salamanders and crocodiles,swing their waists while climbing on horizontal or vertical surfaces.Accompanied by body movement,the centroid trajectory also becomes more of a zigzag path rather than a straight line.Inspired by gecko's gait and posture on a vertical surface,a gecko inspired model with one pendular waist and four active axil legs,which is called GPL model,is proposed.Relationship between the waist position,dynamic gait,and driving forces on supporting feet is analyzed.As for waist trajectory planning,a singular line between the supporting feet is found and its effects on driving forces are discussed.Based on the GPL model,it is found that a sinusoidal waist trajectory,rather than a straight line,makes the driving forces on the supporting legs smaller.Also,a waist close to the pygal can reduce the driving forces compared to the one near middle vertebration,which is in accord with gecko's body bending in the process of climbing.The principles of configuration design and gait planning are proposed based on theoretical analyses.Finally,a bio-inspired robot DracoBot is developed and both of the driving force measurements and climbing experiments reinforce theoretical analysis and the rationality of gecko's dynamic gait.     

Effects of substrate structure on speed and acceleration capacity in climbing geckos

We studied the effects of substrate structure on locomotor performance in a climbing gecko, Hemidactylus garnoti . We quantified three performance traits (acceleration capacity, instantaneous speed, and final speed) on three substrates: (i) smooth wood, (ii) a cloth surface, and (iii) a wire mesh. While acceleration capacity and instantaneous speed were highest on the wooden surface, final speed did not differ significantly among substrates. Using scanning electron microscopy (SEM) pictures, we estimated that 98% of the wooden surface is available for adhesion by the setae on the toepads, while this percentage is much lower for the mesh and cloth (41 and 37%, respectively). We suggest that when a gecko climbs up a gap-filled substrate, such as the wire mesh or cloth, adhesion will only happen between part of the toepad and the substrate, resulting in a diminished acceleration capacity. The higher acceleration capacity on the wooden substrate and the fact that the geckos tend to slip less often on this particular surface, may explain the difference in instantaneous speed. As for final speed, geckos might achieve similar final speeds on all three substrates by employing different locomotor strategies. Our results suggest that microhabitat use in nature might have a profound effect on locomotor performance and survival for climbing lizards such as geckos.  © 2005 The Linnean Society of London, Biological Journal of the Linnean Society , 2005, 85 , 385–393.     

Abigaille-Ⅲ： A Versatile,Bioinspired Hexapod for Scaling Smooth Vertical Surfaces

This paper presents a novel, legged robot, Abigaille-Ⅲ, which is a hexapod actuated by 24 miniature gear motors. This robot uses dual-layer dry adhesives to climb smooth, vertical surfaces. Because dry adhesives are passive and stick to various surfaces, they have advantages over mechanisms such as suction, claws and magnets. The mechanical design and posture of Abigaille-Ⅲ were optimized to reduce pitchback forces during vertical climbing. The robot＇s electronics were designed around a Field Programmable Gate Array, producing a versatile computing architecture. The robot was reconfigured for vertical climbing with both 5 and 6 legs, and with 3 or 4 motors per leg, without changes to the electronic hardware. Abigaille-Ⅲ demonstrated dexterity through vertical climbing on uneven surfaces, and by transferring between horizontal and vertical sur- faces. In endurance tests, Abigaille-Ⅲ completed nearly 4 hours of continuous climbing and over 7 hours of loitering, showing that dry adhesive climbing systems can be used for extended missions.     

Using testis size to predict the mating systems of New Zealand geckos

Abstract

The mating system is unknown for the majority of New Zealand geckos (Family Gekkonidae). I investigated interspecific variation in relative testis volume across 19 New Zealand gecko taxa and 63 additional species of squamate reptiles from other countries to make predictions about the social mating system of the New Zealand geckos. Relative testis size varied greatly between species of New Zealand gecko, with testes ranging from 119% larger than expected to 75% smaller than expected. This variation was even greater across other squamates, with testes ranging from 55 to 152% of expected size. This variation could not be explained by seasonality of breeding, clutch size or the sex ratio of populations. As species subject to more intense sperm competition sport relatively larger testes in other vertebrate groups, it is likely that similar variation in gecko testis size is due to differences in mating systems between species. Based on testis volume, it is predicted that at least half of the New Zealand gecko taxa studied are likely to have polygynandrous mating systems.     

Gecko Adhesion on Wet and Dry Patterned Substrates

Perhaps one of the most astounding characteristics of the gecko adhesive system is its versatility. Geckos can locomote across complex substrates in a variety of conditions with apparent ease. In contrast, many of our synthetic pressure sensitive adhesives fail on substrates that are dirty, wet or rough. Although many studies have investigated the effect of environmental challenges on performance, the interaction of multiple, potentially compromising variables is studied less often. Here we focus on substrate structure and surface water, both of which are highly relevant to the biological system and to synthetic design. To do this we utilized a highly controlled, patterned substrate (Sharklet^®, by Sharklet^® Technologies Inc.). This allowed us to test independently and jointly the effects of reduced surface area substrates, with a defined pattern, on adhesion in both air and water. Our results show that adhesion is not significantly impaired in air, whereas surface area and pattern significantly affect adhesion in water. These findings highlight the need to study multiple parameters that are relevant to the gecko adhesive system to further improve our understanding of the biological system and to design better, more versatile synthetics.     

The nature of the gecko lizard adhesive force

The extraordinary climbing skills of gecko lizards have been under investigation for a long time. Here we report results of direct measurement of single spatula forces in air with varying relative humidities and in water, by the force-distance method using an atomic force microscope. We have found that the presence of water strongly affects the adhesion force and from analysis of our results, we have demonstrated that the dominant force involved is the capillary force.     

Ultrahydrophobicity indicates a non-adhesive default state in gecko setae

Geckos may represent the world’s most demanding adhesives application. The adhesive setae on the toes of climbing geckos must adhere strongly yet avoid fouling or attachment at inappropriate times. We tested the hypothesis that gecko setae are non-adhesive in their unloaded default state by comparing the water droplet contact angle (θ) of isolated setal arrays to the smooth surface of eye spectacle scales of tokay geckos (Gekko gecko). At equilibrium, θ was 98.3 ± 3.4° in spectacle scales of live geckos and 93.3 ± 3.5° in isolated spectacles. Isolated setal arrays were ultrahydrophobic, with θ of 160.6 ± 1.3° (means ± SD). The difference in θ of setal arrays and smooth spectacles indicates a very low contact fraction. Using Cassie’s law of surface wettability, we infer that less than 6.6% of the surface of unloaded setae is solid and at least 93.4% is air space. We calculated that the contact fraction must increase from 6.6% in the unloaded state to 46% in the loaded state to account for previously measured values of adhesion. Thus gecko setae may be non-sticky by default because only a very small contact fraction is possible without mechanically deforming the setal array.     

A System Design Concept Based on Omni-Directional Mobility,Safety and Modularity for an Autonomous Mobile Soccer Robot

In this paper, we describe the concept, design and implementation of a series of autonomous mobile soccer robots, named Musashi robots, which are designed referring ISO safety standards and have mechatronics modular architecture. The robots are designed to participate in the RoboCup Middle Size League. Using a modular design philosophy, we show that the selection of a proper moving mechanism, a suitable vision system and a mechatronics modular architecture design can lead to the realization of a reliable, simple, and low cost robot when compared with most car-like robots that include many kinds of sensors and have a complex design structure.     

Tail regeneration in the gecko Sphaerodactylus argus shows that the formation of an axial elastic skeleton is functional for the new tail

Tail regeneration in the gecko Sphaerodactylus argus shows that the formation of an axial elastic skeleton is functional for the new tail (Acta Zoologica, Stockolm). The present autoradiographic and immunohistochemical study describes tail regeneration and formation of the axial skeleton in early regenerating tails of the Jamaican red-tailed gecko, Sphaerodactylus argus. Cell proliferation, studied by tritiated thymidine, shows intense labelling mainly in forming scales and differentiating cartilaginous, muscle and ependymal cells of the regenerating spinal cord, while the labelling is more diffuse in the apical blastema and proximal connective tissues. The slow apical proliferation maintains the tail front growing while in more proximal regions, cells initiate differentiation, losing thymidine-labelling. Cell proliferation is maximal at the beginning of scales, muscles and cartilage formation. Scales are regenerated following migration into the dermis of tritiated thymidine-labelled keratinocytes to form epithelial pegs that later split and give rise new scales. Differentiation of new corneous layers begins underneath the external corneous epidermis, starting with a shedding layer followed by a beta-layer that accumulates corneous beta proteins. Intense proliferation of apical myoblasts gives rise to long myotubes and segmented muscles. The vertebral column is substituted with a cartilaginous tube made of turgid chondrocytes accumulating chondroitin sulphate proteoglycan and elastin. Therefore, the regenerated tail remains flexible and capable of curling to maintain efficient the climbing ability in these geckos.     

Involvement of gecko SNAP25b in spinal cord regeneration by promoting outgrowth and elongation of neurites

SNARE complex mediates cellular membrane fusion events essential for neurotransmitter release and synaptogenesis. SNAP25, a member of the SNARE proteins, plays critical roles during the development of the central nervous system via regulation by alternative splicing and protein kinase phosphorylation. To date, little information is available regarding the protein in the spinal cord regeneration, especially for the postnatal highly expressed isoform SNAP25b. In the present study, we characterized gecko SNAP25b, which shared high identity with those of other vertebrates. Expression of gecko SNAP25b was temporally upregulated in both neurons of spinal cord and forming ependymal tube following tail amputation, coinciding with the occurrence of regenerate re-innervation. Overexpression of gecko wild type SNAP25b in the SH-SY5Y and undifferentiated PC12 cells promoted the elongation and outgrowth of neurites, while mutant constructs at Serine¹⁸⁷ resulted in differential effects for which S187A had a promoting role. Knockdown of endogenous SNAP25b affected the formation of neurites, which could be rescued by overexpression of SNAP25b. FM1-43 staining revealed that transfection of S187E mutant construct reduced the recruitment of vesicles. In addition, transfection of gecko SNAP25b in the astrocyte, which is absent from neuronal specific VAMP2, was capable of enhancing process elongation, indicating a potential for various alternative protein combinations. Taken together, our data suggest that gecko SNAP25b is involved in spinal cord regeneration by promoting outgrowth and elongation of neurites in a more extensive protein binding manner.     

Local force cues for strength and stability in a distributed robotic construction system

Construction of spatially extended, self-supporting structures requires a consideration of structural stability throughout the building sequence. For collective construction systems, where independent agents act with variable order and timing under decentralized control, ensuring stability is a particularly pronounced challenge. Previous research in this area has largely neglected considering stability during the building process. Physical forces present throughout a structure may be usable as a cue to inform agent actions as well as an indirect communication mechanism (stigmergy) to coordinate their behavior, as adding material leads to redistribution of forces which then informs the addition of further material. Here we consider in simulation a system of decentralized climbing robots capable of traversing and extending a two-dimensional truss structure, and explore the use of feedback based on force sensing as a way for the swarm to anticipate and prevent structural failures. We consider a scenario in which robots are tasked with building an unsupported cantilever across a gap, as for a bridge, where the goal is for the swarm to build any stable spanning structure rather than to construct a specific predetermined blueprint. We show that access to local force measurements enables robots to build cantilevers that span significantly farther than those built by robots without access to such information. This improvement is achieved by taking measures to maintain both strength and stability, where strength is ensured by paying attention to forces during locomotion to prevent joints from breaking, and stability is maintained by looking at how loads transfer to the ground to ensure against toppling. We show that swarms that take both kinds of forces into account have improved building performance, in both structured settings with flat ground and unpredictable environments with rough terrain.     

The Energy Expenditure of Stair Climbing One Step and Two Steps at a Time: Estimations from Measures of Heart Rate

Stairway climbing provides a ubiquitous and inconspicuous method of burning calories. While typically two strategies are employed for climbing stairs, climbing one stair step per stride or two steps per stride, research to date has not clarified if there are any differences in energy expenditure between them. Fourteen participants took part in two stair climbing trials whereby measures of heart rate were used to estimate energy expenditure during stairway ascent at speeds chosen by the participants. The relationship between rate of oxygen consumption () and heart rate was calibrated for each participant using an inclined treadmill. The trials involved climbing up and down a 14.05 m high stairway, either ascending one step per stride or ascending two stair steps per stride. Single-step climbing used 8.5±0.1 kcal min⁻¹, whereas double step climbing used 9.2±0.1 kcal min⁻¹. These estimations are similar to equivalent measures in all previous studies, which have all directly measured The present study findings indicate that (1) treadmill-calibrated heart rate recordings can be used as a valid alternative to respirometry to ascertain rate of energy expenditure during stair climbing; (2) two step climbing invokes a higher rate of energy expenditure; however, one step climbing is energetically more expensive in total over the entirety of a stairway. Therefore to expend the maximum number of calories when climbing a set of stairs the single-step strategy is better.     

Robot control and the evolution of modular neurodynamics

Summary A modular approach to neural behavior control of autonomous robots is presented. It is based on the assumption that complex internal dynamics of recurrent neural networks can efficiently solve complex behavior tasks. For the development of appropriate neural control structures an evolutionary algorithm is introduced, which is able to generate neuromodules with specific functional properties, as well as the connectivity structure for a modular synthesis of such modules. This so called ENS ³-algorithm does not use genetic coding. It is primarily designed to develop size and connectivity structure of neuro-controllers. But at the same time it optimizes also parameters of individual networks like synaptic weights and bias terms. For demonstration, evolved networks for the control of miniature Khepera robots are presented. The aim is to develop robust controllers in the sense that neuro-controllers evolved in a simulator show comparably good behavior when loaded to a real robot acting in a physical environment. Discussed examples of such controllers generate obstacle avoidance and phototropic behaviors in non-trivial environments.     

Mobile image sensors for object detection using color segmentation

The intelligent mobile robot with sensors and image processing embedded system combines the suction and aerodynamic attraction to achieve good balance between strong adhesion force and high mobility. Experimental results showed that the robot can move upward on the wall at the speed of 2.9 m/min and carry 5 kg payload in addition to 2.5 kg self-weight, which record the highest payload capacity among climbing robots of similar size. It also implements object detection ability using effective color transform and segmentation technique for the exact target detection on the wall using a embedded camera system, communication module and several active sensors.     

Building of a Conservation Breeding Facility for the Psychedelic Rock Gecko (Cnemaspis psychedelica) in Southern Vietnam

Vietnam belongs to the global hotspots of biodiversity, and new vertebrate species have been regularly discovered from this country. Lizards and in particular geckos are among the groups with the highest discovery rates. One of the most beautiful geckos recently discovered from Vietnam is the Psychedelic Rock Gecko (Cnemaspis psychedelica), an endemic species of Hon Khoai Island, a small island with a total area of only 8 km² in Ca Mau Province, southern Vietnam. Although Hon Khoai is protected through the Ca Mau Biosphere Reserve, and collecting and exporting of the wild fauna and flora for commercial purpose is prohibited, the beautiful geckos made their way to the international pet trade. But the species is not only threatened by illegal collecting for the pet trade, but also by macaques introduced on this island. To act against this alarming development, Wildlife at Risk (WAR), the Institute of Ecology and Biological Resources (IEBR) and Cologne Zoo decided to cooperate in building up a gecko house as basis for the establishment of a reserve population, which could become the beginning of a potential conservation breeding program for C. psychedelica. The gecko house was planned in May 2014 and finished in November 2014 in WAR's Hon Me Station in Kien Giang Province, southern Vietnam. It has a movable rain cover with sunblind and contains ten large terraria consisting of aluminium, metal gauze and glass. Terrarium furniture mainly consists of cemented rock walls, plants, and natural soil with leaves. The gecko house also has a double door system to prevent accidently escaped geckos from breaking out. The exterior of the gecko house is covered by a large water proof poster which points both in English and Vietnamese languages to the threats to the Psychedelic Rock Gecko and the background of the conservation project. First small gecko breeding groups were transferred from Hon Khoai Island to the Hon Me Station in March 2015, with relevant permits provided by the respective authorities. Furthermore we report about our first experiences with the keeping and breeding of C. psychedelica, and document colour pattern change during juvenile development.     

Concept of Intelligent Mechanical Design for Autonomous Mobile Robots

The concept of Intelligent Mechanical Design (IMD) is presented to show how a mechanical structure can be designed to affect robot controllability, simplification and task performance. Exploring this concept produces landmarks in the territory of mechanical robot design in the form of seven design principles. The design principles, which we call the Mecha-Telligence Principles (MTP), provide guidance on how to design mechanics for autonomous mobile robots. These principles guide us to ask the right questions when investigating issues concerning self-controllable, reliable, feasible, and compatible mechanics for autonomous mobile robots. To show how MTP can be applied in the design process we propose a novel methodology, named as Mecha-Telligence Methodology (MTM). Mechanical design by the proposed methodology is based on preference classification of the robot specification described by interaction of the robot with its environment and the physical parameters of the robot mechatronics. After defining new terms, we investigate the feasibility of the proposed methodology to the mechanical design of an autonomous mobile sewer inspection robot. In this industrial project we show how a passive-active intelligent moving mechanism can be designed using the MTM and employed in the field.