Mole rat (Scaptochirus moschatus), a soil-burrowing mammal, can efficiently dig soil using its fore claws. The profile curves of its claw toe provide excellent structure for digging. In this paper, a biomimetic stubble-cutting disc was designed by learning from the geometrical characteristics of the mole rat claw toes. To compare the structural strength and working effi-ciency of the biomimetic disc and the conventional stubble-cutting disc, three-dimensional (3D) models of the discs were built and numerical analyzed in ABAQUS. In the dynamic soil cutting model, soil was modeled as an elastic-plastic material with elastic parameters, including Young’s modulus, Poisson’s ratio and Drucker-Prager criterion, which were obtained from triaxial tests. A general contact algorithm was used to simulate the interaction between rotary disc and soil. In FEA models, for the combined action of normal and friction stresses, the stress on the biomimetic disc is 34.33 % lower than that of the conventional disc. For only the normal stress, the stress on the biomimetic disc is 22.64% lower than that on the conventional one. The magnitude of soil stress in biomimetic disc cutting model is 6.87% higher than that in conventional disc. The FEA results indicate that the biomimetic disc performs better in structural strength and cutting efficiency.

A computer-aided design model for a fixed partial denture was constructed and used in a finite element analysis to study the overall load sharing mechanism between the fixed partial denture and oral structures while the denture base rested on the alveolar ridge. To investigate the consequences of non-contact conditions, three additional models were generated incorporating a uniform clearance of 0.125 mm, 0.25 mm, and 0.5 mm, respectively. A 100 N static load located at the free end of the pros-thesis was applied while the distal portion of the jaw was set fixed. The results show that whilst releasing the ridge almost entirely, the presence of the clearance drastically increased the load on the splinting teeth. A pull-out force on the canine tooth of about 44 N was computed, accompanied by a mesio-distal moment of about 500 N?cm. The combination of which was similar to the tooth extraction maneuver performed by the dentist. In contrast, the second premolar was found to bear a push-in force of almost 115 N. The first molar, though barely solicited in the contact condition, became substantially loaded in non-contact conditions, which validates the choice of sacrificing three teeth to support the denture.

This paper presents a novel Central Pattern Generator (CPG) based rolling gait generation in a small-sized spherical robot and its nonlinear control mechanism. A rhythmic rolling pattern mimicking Pleurotya caterpillar is produced for the spherical robot locomotion. A synergetically combined feedforward-feedback control strategy is proposed. The feedforward component is generated from centrally connected network of CPGs in conjunction with nonlinear robot dynamics. Two nonlinear feedback control methods namely integral (first order) Sliding Mode Control (SMC) and High (or second) Order Sliding Mode Control (HOSMC) are proposed to regulate robot stability and gait robustness in the presence of matched parameter uncertainties and bounded external disturbances. Design, implementation and experimental evaluation of both roll gait control strategies for the spherical robot are done on smooth (indoor) and irregular (outdoor) ground surfaces. The performance of robot control is quantified by measuring the roll angle stability, phase plane convergence and wheel velocities. Experimental results show that proposed novel strategy is efficient in producing a stable rolling gait and robust control of a spherical robot on two different types of surfaces. It further shows that proposed high HOSMC strategy is more efficient in robust rolling gait control of a spherical robot compared to an integral first-order SMC on two different ground conditions.

When developing microscale robotic systems it is desired that they are capable of performing microscale tasks such as small scale manipulation and transport. In this paper, we demonstrate the transport of microscale objects using single or multiple microrobots in low Reynolds number fluidic environment. The microrobot is composed of a ‘U’ shaped SU-8 body, coated on one side with nickel. Once the nickel coating is magnetized, the motion of the microrobots can be driven by external magnetic fields. To invoke different responses from two microrobots under a global magnetic field, two batches of microrobots were fabricated with different thicknesses of nickel coating as a way to promote heterogeneity within the microrobot population. The heterogeneity in magnetic content induces different spatial and temporal responses under the same control input, resulting in differences in movement speed. The nickel coated microstructure is manually controlled through a user interface developed using C++. This paper presents a control strategy to navigate the microrobots by controlling the direction and strength of ex-ternally applied magnetic field, as well as orientation of the microrobots based on their polarity. In addition, multiple micro-robots are used to perform transport tasks.

A new method for iris recognition using a multi-matching system based on a simplified deformable model of the human iris was proposed. The method defined iris feature points and formed the feature space based on a wavelet transform. In the matching stage it worked in a crude manner. Driven by a simplified deformable iris model, the crude matching was refined. By means of such multi-matching system, the task of iris recognition was accomplished. This process can preserve the elastic deformation between an input iris image and a template and improve precision for iris recognition. The experimental results indicate the va-lidity of this method.

A superhydrophobic manganese oxide/polystyrene (MnO2/PS) nanocomposite coating was fabricated by a facile spraying process. The mixture solution of MnO2/PS was poured into a spray gun, and then sprayed onto the copper substrate using 0.2 MPa nitrogen gas to construct superhydrophobic coating. The wettability of the composite coating was measured by sessile drop method. When the weight ratio of MnO2 to PS is 0.5:1, the maximum of contact angle (CA) (140?) is obtained at drying temperature of 180 ?C. As the content of MnO2 increases, the maximum of CA (155?) is achieved at 100 ?C. Surface morphologies and chemical composition were analyzed to understand the effect of the content of MnO2 nanorods and the drying temperature on CA. The results show that the wettability of the coating can be controlled by the content of MnO2 nanorods and the drying temperature. Using the proposed method, the thickness of the coating can be controlled by the spraying times. If damaged, the coating can be repaired just by spraying the mixture solution again.

This paper presents the design, fabrication, and experimental characterization of a peristaltic micropump. The micropump is composed of two layers fabricated from Polydimethylsiloxane (PDMS) material. The first layer has a rectangular channel and two valve seals. Three rectangular mini lightweight piezo-composite actuators are integrated in the second layer, and used as actuation parts. Two layers are bonded, and covered by two Polymethyl Methacrylate (PMMA) plates, which help increase the stiffness of the micropump. A maximum flow rate of 900 mL•min⁻¹and a maximum backpressure of 1.8 kPa are recorded when water is used as pump liquid. We measured the power consumption of the micropump. The micropump is found to be a prom-ising candidate for bio-medical application due to its bio-compatibility, portability, bidirectionality, and simple effective design.

There is increasing observational evidence indicating that crystalline interfacial water layers play a central role in evolution and biology. For instance in cellular recognition processes, in particular during first contact events, where cells decide upon survival or entering apoptosis. Understanding water layers is thus crucial in biomedical engineering, specifically in the design of biomaterials inspired by biomimetic principles. Whereas there is ample experimental evidence for crystalline interfacial water layers on surfaces in air, their subaquatic presence could not be verified directly, so far. Analysing a polarity dependent asym-metry in the surface conductivity on hydrogenated nanocrystalline diamond, we show that crystalline interfacial water layers persist subaquatically. Nanoscopic interfacial water layers with an order different from that of bulk water have been identified at room temperature on both hydrophilic and hydrophobic model surfaces – in air and subaquatically. Their generalization and systematic inclusion into the catalogue of physical and chemical determinants of biocompatibility complete the biomimetic triangle.

Structured poly(dimethylsiloxane) (PDMS) chambers were designed and fabricated to enhance the signaling of human Embryonic Stem Cell (hESC) - derived neuronal networks on Microelectrode Array (MEA) platforms. The structured PDMS chambers enable cell seeding on restricted areas and thus, reduce the amount of needed coating materials and cells. In addition, the neuronal cells formed spontaneously active networks faster in the structured PDMS chambers than that in control chambers. In the PDMS chambers, the neuronal networks were more active and able to develop their signaling into organized signal trains faster than control cultures. The PDMS chamber design enables much more repeatable analysis and rapid growth of functional neuronal network in vitro. Moreover, due to its easy and cheap fabrication process, new configurations can be easily fabricated based on investigator requirements.

Ionic Polymer Metal Composite (IPMC) can be used as an electrically activated actuator, which has been widely used in artificial muscles, bionic robotic actuators, and dynamic sensors since it has the advantages of large deformation, light weight, flexibility, and low driving voltage, etc. To further improve the mechanical properties of IPMC, this paper reports a new method for preparing organic-inorganic hybrid Nafion/SiO2 membranes. Beginning from cast Nafion membranes, IPMCs with various tetraethyl orthosilicate (TEOS) contents were fabricated by electroless plating. The elastic moduli of cast Nafion membranes were measured with nano indenters, the water contents were calculated, and the cross sections of Nafion membranes were observed by scanning electron microscopy. The blocking force, the displacement, and the electric current of IPMCs were then measured on a test apparatus. The results show that the blocking force increases as the TEOS content gradually increases, and that both the displacement and the electric current initially decrease, then increase. When the TEOS content is 1.5%, the IPMC shows the best improved mechanical properties. Finally, the IPMC with the best improved performance was used to successfully actuate the artificial eye and tested.

Publication rate of patents can be a useful measure of innovation and productivity in fields of science and technology. To assess the growth in industrially-important research, I conducted an appraisal of patents published between 1985 and 2005 on online databases using keywords chosen to select technologies arising as a result of biological inspiration.
Whilst the total number of patents increased over the period examined, those with biomimetic content had increased faster as a proportion of total patent publications. Logistic regression analysis reveals that we may be a little over half way through an initial innovation cycle inspired by biological systems.

To reduce friction drag with bionic method in a more feasible way, the surface microstructure of fish scales was analyzed attempting to reveal the biologic features responding to skin friction drag reduction. Then comparable bionic surface mimicking fish scales was fabricated through coating technology for drag reduction. The paint mixture was coated on a substrate through a self-developed spray-painting apparatus. The bionic surface with micron-scale caves formed spontaneously due to the interfacial convection and deformation driven by interfacial tension gradient in the presence of solvent evaporation. Comparative experiments between bionic surface and smooth surface were performed in a water tunnel to evaluate the effect of bionic surface on drag reduction, and visible drag reduction efficiency was obtained. Numerical simulation results show that gas phase develops in solid-liquid interface of bionic surface with the effect of surface topography and partially replaces the solid-liquid shear force with gas-liquid shear force, hence reducing the skin friction drag effectively. Therefore, with remarkable drag reduction performance and simple fabrication technology, the proposed drag reduction technique shows the promise for practical applications.

A CPG control mechanism is proposed for hopping motion control of biped robot in unpredictable environment. Based on analysis of robot motion and biological observation of animal’s control mechanism, the motion control task is divided into two simple parts: motion sequence control and output force control. Inspired by a two-level CPG model, a two-level CPG control mechanism is constructed to coordinate the drivers of robot joint, while various feedback information are introduced into the control mechanism. Interneurons within the control mechanism are modeled to generate motion rhythm and pattern promptly for motion sequence control; motoneurons are modeled to control output forces of joint drivers in real time according to feedbacks. The control system can perceive changes caused by unknown perturbations and environment changes according to feedback information, and adapt to unpredictable environment by adjusting outputs of neurons. The control mechanism is applied to a biped hopping robot in unpredictable environment on simulation platform, and stable adaptive motions are obtained.

The survival oriented adaptation of evolved biosystems to variations in their environment is a selective optimization process. Recognizing the optimised end product and its functionality is the classical arena of bionic engineering. In a primordial world, however, the molecular organization and functions of prebiotic systems were solely defined by formative processes in their physical and chemical environment, for instance, the interplay between interfacial water layers on surfaces and solar light. The formative potential of the interplay between light (laser light) and interfacial water layers on surfaces was recently exploited in the formation of supercubane carbon nanocrystals. In evolved biosystems the formative potential of interfacial water layers can still be activated by light. Here we report a case of hay fever, which was successfully treated in the course of a facial reju-venation program starting in November 2007. Targeting primarily interfacial water layers on elastin fibres in the wrinkled areas, we presumably also activated mast cells in the nasal mucosa, reported to progressively decrease in the nasal mucosa of the rabbit, when frequently irradiated. Hay fever is induced by the release of mediators, especially histamine, a process associated with the degranulation of mast cells. Decrease in mast cells numbers implies a decrease in the release of histamine. To the best of our knowledge this is the first report on the treatment of hay fever with visible light. This approach was inspired by bionic thinking, and could help ameliorating the condition of millions of people suffering from hay fever world wide.

This paper describes a novel wavelet-based approach to the detection of abrupt fault of Rotorcraft Unmanned Aerial Ve-hicle (RUAV) sensor system. By use of wavelet transforms that accurately localize the characteristics of a signal both in the time and frequency domains, the occurring instants of abnormal status of a sensor in the output signal can be identified by the multi-scale representation of the signal. Once the instants are detected, the distribution differences of the signal energy on all decomposed wavelet scales of the signal before and after the instants are used to claim and classify the sensor faults.

Structural stabilization by a pressurized fluid is very common in nature, however hardly found in technology. Car tires, hot air balloons, airships and airhouses are among the few technical exceptions, which are stabilized by a compressed medium, typically air. Restricted by simple geometries and a very limited load bearing capacity these pneumatic structures could succeed only in very specialized applications. Nevertheless, prospective concepts ag has systematically investigated pneumatic structures during the last few years. As a major result, it was demonstrated that almost any shape can be made with pneumatic structures and that astonishing structures such as the pneumatic airplane Stingray can be realized even with low air pressure. On top of that, Airlight Ltd. in close collaboration with prospective concepts ag has recently developed the fundamental new structural concept Tensairity. The synergetic combination of an inflated structure with conventional structural elements such as cables and struts yields pneumatic light-weight structures with the load bearing capacity of steel girders. Thus, complex forms and high strength open up many new o pportunities for pressure induced stability in technology. An overview of these recent developments is presented and the close relationship of pneumatic structures with biology is outlined.

Effect of initial interference fit on pull-out strength in cementless fixation between bovine tibia and smooth stainless steel post was investigated in this study. Compressive behavior of bovine spongious bone was studied using mechanical testing in order to evaluate the elastic-plastic properties in different regions of the proximal tibia. Friction tests were carried out in the aim to evaluate the friction behavior of the contact between bovine spongious bone and stainless steel. A cylindrical stainless steel post inserted in a pre-drilled bovine tibia with an initial interference fit was taken as an in vitro model to assess the contribution of post fixation to the initial stability of the Total Knee Arthroplasty (TKA) tibial component. Pull-out experiments were carried out for different initial interference fits. Finite Element Models (FEM) using local elastic-plastic properties of the bovine bone were developed for the analysis of the experimental ultimate pull-out force results. At the post/bone interface, Coulomb friction was considered in the FEM calculations with pressure-dependent friction coefficient. It was found that the FEM results of the ultimate force are in good agreement with the experimental results. The analysis of the FEM interfacial stresses indicates that the micro-slip initiation depends on the local bone properties.

This paper presents the dynamic modeling of a flexible tail for a robotic fish. For this purpose firstly, the flexible tail was simplified as a slewing beam actuated by a driving moment. The governing equation of the flexible tail was derived by using the Euler-Bernoulli theory. In this equation, the resistive forces were estimated as a term analogous to viscous damping. Then, the modal analysis method was applied in order to derive an analytical solution of the governing equation, by which the relationship between the driving moment and the lateral movement of the flexible tail was described. Finally, simulations and experiments were carried out and the results were compared to verify the accuracy of the dynamic model. It was proved that the dynamic model of a fish robot with a flexible tail fin well explains the real behavior of robotic fish in underwater environment.

The tangent resistance on the interface of the soilmoldboard is an important component of the resistance to moving soil . We developed simplified mechanical models to analyze this resistance. We found that it is composed of two components, the frictional and adhesive resistances. These two components originate from the soil pore, which induced a capillary suction effect, and the soilmoldboard contact area produced tangent adhesive resistance. These two components varied differently with soil moisture. Thus we predicted that resistance reduction against soil exerted on the nonsmooth bionic moldboard is mainly due to the elimination of capillary suction and the reduction of physicalchemical adsorption of soil.

Ultra High Molecular Weight Polyethylene (UHMWPE) has been widely used as a bearing material for artificial joint re-placement over forty years. It is usually crosslinked by gamma rays irradiation before its implantation into human body. In this study, UHMWPE and UHMWPE/nano-hydroxyapatite (n-HA) composite were prepared by vacuum hot-pressing method. The prepared materials were irradiated by gamma rays in vacuum and molten heat treated in vacuum just after irradiation. The effect of filling n-HA with gamma irradiation on tribological properties of UHMWPE was investigated by using friction and wear experimental machine (model MM-200) under deionized water lubrication. Micro-morphology of worn surface was observed by metallographic microscope. Contact angle and hardness of the materials were also measured. The results show that contact angle and hardness are changed by filling n-HA and gamma irradiation. Friction coefficient and wear rate under deionized water lubrication are reduced by filling n-HA. While friction coefficient is increased and wear rate is reduced significantly by gamma irradiation. The worn surface of unfilled material is mainly characterized as adhesive wear and abrasive wear, and that of n-HA filled material is mainly characterized as abrasive wear. After gamma irradiation, the degrees of adhesive and abrasive wear for unfilled material and abrasive wear of n-HA filled material are significantly reduced. Unfilled and filled materials after irra-diation are mainly shown as slight fatigue wear. The results indicate that UHMWPE and UHMWPE/n-HA irradiated at the dose of 150 kGy can be used as bearing materials in artificial joints for its excellent wear resistance compared to original UHMWPE.

A review on the research of Micro Electromechanical Systems (MEMS) technology based biomimetic cilia is presented. Biomimetic cilia, enabled by the advancement of MEMS technology, have been under dynamic development for the past decade. After a brief description of the background of cilia and MEMS technology, different biomimetic cilia applications are reviewed. Biomimetic cilia micro-actuators, including micromachined polyimide bimorph biomimetic cilia micro-actuator, electro-statically actuated polymer biomimetic cilia micro-actuator, and magnetically actuated nanorod array biomimetic cilia micro-actuator, are presented. Subsequently micromachined underwater flow biomimetic cilia micro-sensor is studied, followed by acoustic flow micro-sensor. The fabrication of these MEMS-based biomimetic cilia devices, characterization of their physical properties, and the results of their application experiments are discussed.

This paper proposes an autopilot system that can be used to control the small scale rotorcraft during the flight test for linear-frequency-domain system identification. The input frequency-sweep is generated automatically as part of the autopilot control command. Therefore the bandwidth coverage and consistency of the frequency-sweep are guaranteed to produce high quality data for system identification. Beside that, we can set the safety parameters during the flight test (maximum roll/pitch value, minimum altitude, etc.•) so the safety of the whole flight test is guaranteed. This autopilot system is validated using hardware in the loop simulator for hover flight condition.

Based on the research of a biological olfactory system, a novel chaotic neural network model - K set model has been es-tablished. This chaotic neural network not only simulates the real brain activity of an olfactory system, but also presents a novel chaotic concept for signal processing and pattern recognition. The characteristics of the K set models are investigated and show that a KIII model can be used for image pattern classification.

Oscillations and their damping were investigated for plant stems of Cyperus alternifolius L., Equisetum hyemale L., Equisetum fluviatile L., Juncus effuses L., Stipa gigantea Link, and Thamnocalamus spathaceus (Franch.) Soderstr. With the exception of T. spathaceus, mechanical damping of the oscillation of individual plant stems, even without side organs, leaves or inflorescences, is quite effective. Our experiments support the hypothesis that embedding stiff sclerenchymatous elements in a more compliant parenchymatous matrix provides the structural basis for the dissipation of mechanical energy in the plant stem.
As an application the naturally occurring structures were mimicked in a compound material made from hemp fabrics embedded in polyurethane foam, cured under pressure. Like its natural model it shows plastic deformability and viscoelastic behaviour. In particular the material is characterized by a remarkably high shock absorption capacity even for high impact loads.

Biological tiny structures have been observed on many kinds of surfaces such as lotus leaves and insect wings, which enhance the hydrophobicity of the natural surfaces and play a role of self-cleaning. We presented the fabrication technology of a superhydrophobic surface using high energy ion beam. Artificial insect wings that mimic the morphology and the superhydrophobocity of cicada’s wings were successfully fabricated using argon and oxygen ion beam treatment on a polytetrafluoroethylene (PTFE) film. The wing structures were supported by carbon/epoxy fibers as artificial flexible veins that were bonded through an autoclave process. The morphology of the fabricated surface bears a strong resemblance to the wing surface of a cicada, with contact angles greater than 160?, which could be sustained for more than two months.

Simulating biological olfactory neural system, KⅢ network, which is a high-dimensional chaotic neural network, is designed in this paper. Different from conventional artificial neural network, the KⅢ network works in its chaotic trajectory. It can simulate not only the output EEG waveform observed in electrophysiological experiments, but also the biological intelligence for pattern classification. The simulation analysis and application to the recognition of handwriting numerals are presented here. The classification performance of the KⅢ network at different noise levels was also investigated.

Some tribological behavior between mature Gampsocleis gratiosa foot pads and vertical flats of different materials were studied in this work. stereomicroscope (SMS) and scanning electron microscope (SEM) were used to measure the morphology of the Gampsocleis gratiosa foot pads. An atomic force microscope (AFM) was used to measure the morphologies of the surfaces of glass and a wall doped with calcium carbonate material. The attaching behavior of Gampsocleis gratiosa feet on the two vertical surfaces was observed. The attaching force (perpendicular to the vertical surface) and the static frictional force (along the direction of gravitation) of Gampsocleis gratiosa foot pads on a vertical glass were measured. It was shown that the average attaching force is 50.59 mN and the static frictional force is 259.10 mN. The physical models of the attaching interface between Gampsocleis gratiosa foot pads and the two vertical surfaces were proposed. It was observed that the foot pads are smooth in macroscale; however, the pad surface is composed by approximate hexagonal units with sizes of 3 μm to 7 μm in microscale; the adjacent units are separated by nanoscale grooves. The Observations showed that the Gampsocleis gratiosa can not climb the vertical calcium carbonate wall; in contrast, they can easily climb the vertical glass surface. Based on the features of the geometrical morphologies of the foot pads and the glass surface, we speculate that the attaching force and strong static frictional force are attributed to the inter-inlays between the deformable Gampsocleis gratiosa foot pads and the nanoscale sharp tips of the glass surface.

This paper introduces a flight simulation of an ornithopter (flapping-wing air vehicle) based on the flexible multi-body dynamics, a refined flapping-wing aerodynamic model and the fluid-structure interaction approach. A simulated ornithopter was modeled using the multi-body dynamics software, MSC.ADAMS, where the flexible parts can be included by importing a finite element model built in the finite element analysis software, ANSYS. To model the complex aerodynamics of flapping-wing, an improved version of modified strip theory was chosen. The proposed integrative simulation framework of ornithopter was validated by the wind tunnel test data reported in the literature. A magpie-sized model ornithopter was numerically designed and simulated to have the longitudinal trim flight condition. We observed a limit-cycle-oscillation of flight state variables, such as pitch attitude, altitude, flight speed, during the trimmed flight of the model ornithopter. Under the trimmed condition of free flight of the model ornithopter, we fixed all the degrees of freedom at the center of gravity to measure the constraint forces and moment. The concept of the “zero moment point” is introduced to explain the physics of ornithopter trimmed longitudinal flight.

Water beetles are proficient drag-powered swimmers, with oar-like legs. Inspired by this mechanism, here we propose a miniature robot, with mobility provided by a pair of legs with swimming appendages. The robot has optimized linkage structure to maximize the stroke angle, which is actuated by a single DC motor with a series of gears and a spring. A simplified swimming appendage model is proposed to calculate the deflection due to the applied drag force, and is compared with simulated data using COMSOL Multiphysics. Also, the swimming appendages are optimized by considering their locations on the legs using two fitness functions, and six different configurations are selected. We investigate the performance of the robot with various types of appendage using a high-speed camera, and motion capture cameras. The robot with the proposed configuration exhibits fast and efficient movement compared with other robots. In addition, the locomotion of the robot is analyzed by considering its dynamics, and compared with that of a water boatman (Corixidae).

A mathematical model is constructed to examine the characteristics of three layered blood flow through the oscillatory cylindrical tube (stenosed arteries). The proposed model basically consists three layers of blood (viscous fluids with different viscosities) named as core layer (red blood cells), intermediate layer (platelets/white blood cells) and peripheral layer (plasma). The analysis was restricted to propagation of small-amplitude harmonic waves, generated due to blood flow whose wave length is larger compared to the radius of the arterial segment. The impacts of viscosity of fluid in peripheral layer and intermediate layer on the interfaces, average flow rate, mechanical efficiency, trapping and reflux are discussed with the help of numerical and computational results. This model is the generalized form of the preceding models. On the basis of present discussion, it is found that the size of intermediate and peripheral layers reduces in expanded region and enhances in contracted region with the increasing viscosity of fluid in peripheral layer, whereas, opposite effect is observed for viscosity of fluid in intermediate layer. Final conclusion is that the average flow rate and mechanical efficiency increase with the increasing viscosity of fluid in both layers, however, the effects of the viscosity of fluid in both layers on trapping and reflux are opposite to each other.

This paper presents a novel approach to modelling carangiform fish-like swimming motion for multi-joint robotic fish so that they can obtain fish-like behaviours and mimic the body motion of carangiform fish. A given body motion function of fish swimming is firstly converted to a tail motion function which describes the tail motion relative to the head. Then, the tail motion function is discretized into a series of tail postures over time. Thirdly, a digital approximation method calculates the turning angles of joints in the tail to approximate each tail posture; and finally, these angles are grouped into a look-up table, or regressed to a time-dependent function, for practically controlling the tail motors in a multi-joint robotic fish. The paper made three contributions: tail motion relative to the head, an error function for digital approximation and regressing a look- up table for online optimization. To prove the feasibility of the proposed methodology, two basic swimming motion patterns, cruise straight and C-shape sharp turning, are modelled and implemented in our robotic fish. The experimental results show that the relative tail motion and the approximation error function are good choices and the proposed method is feasible.

The human foot is a very complex structure comprising numerous bones, muscles, ligaments and synovial joints. As the only component in contact with the ground, the foot complex delivers a variety of biomechanical functions during human locomotion, e.g. body support and propulsion, stability maintenance and impact absorption. These need the human foot to be rigid and damped to transmit ground reaction forces to the upper body and maintain body stability, and also to be compliant and resilient to moderate risky impacts and save energy. How does the human foot achieve these apparent conflicting functions? In this study, we propose a phase-dependent hypothesis for the overall locomotor functions of the human foot complex based on in-vivo measurements of human natural gait and simulation results of a mathematical foot model. We propse that foot functions are highly dependent on gait phase, which is a major characteristics of human locomotion. In early stance just after heel strike, the foot mainly works as a shock absorber by moderating high impacts using the viscouselastic heel pad in both vertical and horizontal directions. In mid-stance phase (~80% of stance phase), the foot complex can be considered as a springy rocker, reserving external mechanical work using the foot arch whilst moving ground contact point forward along a curved path to maintain body stability. In late stance after heel off, the foot complex mainly serves as a force modulator like a gear box, modulating effective mechanical advantages of ankle plantiflexor muscles using metatarsal-phalangeal joints. A sound under-standing of how diverse functions are implemented in a simple foot segment during human locomotion might be useful to gain insight into the overall foot locomotor functions and hence to facilitate clinical diagnosis, rehabilitation product design and humanoid robot development.

Inspired by the coarse-to-fine visual perception process of human vision system, a new approach based on Gaussian multi-scale space for defect detection of industrial products was proposed. By selecting different scale parameters of the Gaussian kernel, the multi-scale representation of the original image data could be obtained and used to constitute the multi-variate image, in which each channel could represent a perceptual observation of the original image from different scales. The Multivariate Image Analysis (MIA) techniques were used to extract defect features information. The MIA combined Principal Component Analysis (PCA) to obtain the principal component scores of the multivariate test image. The Q-statistic image, derived from the residuals after the extraction of the first principal component score and noise, could be used to efficiently reveal the surface defects with an appropriate threshold value decided by training images. Experimental results show that the proposed method performs better than the gray histogram-based method. It has less sensitivity to the inhomogeneous of illumination, and has more robustness and reliability of defect detection with lower pseudo reject rate.

Magnesium-based alloys are frequently reported as potential biodegradable orthopedic implant materials. Controlling the degradation rate and mechanical integrity of magnesium alloys in the physiological environment is the key to their applications. In this study, calcium phosphate (Ca-P) coating was prepared on AZ60 magnesium alloy using phosphating technology. AZ60 samples were immersed in a phosphating solution at 37 ± 2 ?C for 30 min, and the solution pH was adjusted to 2.6 to 2.8 by adding NaOH solution. Then, the samples were dried in an attemperator at 60 ?C. The degradation behavior was studied in vivo using Ca-P coated and uncoated magnesium alloys. Samples of these two different materials were implanted into rabbit femora, and the corrosion resistances were evaluated after 1, 2, and 3 months. The Ca-P coated samples corroded slower than the un-coated samples with prolonged time. Significant differences (p < 0.05) in mass losses and corrosion rates between uncoated samples and Ca-P coated samples were observed by micro-computed tomography. The results indicate that the Ca-P coating could slow down the degradation of magnesium alloy in vivo.

An area of protruding feathers found around the beak of many penguin species is thought to induce a turbulent boun~dary layer whilst swimming. Hydrodynamic tests on a model Humboldt penguin, Spheniscus humboldti, suggest that induced turbulence causes a significant reduction in boundary layer height, flow separation, and an average of 31 % reduction in drag (1.0 m/s to 4.5 m/s). Visualisation of surface flow showed it to follow the body profile, over the feet and tail, before separating. Movement of the feet in swimming penguins correlates with steering of the bird. Induced turbulence may therefore further increase swimming efficiency by reducing the amount of foot movement required to direct the swimming bird.

A bio-robot system refers to an animal equipped with Brain-Computer Interface (BCI), through which the outer stimulation is delivered directly into the animal’s brain to control its behaviors. The development of bio-robots suffers from the dependency on real-time guidance by human operators. Because of its inherent difficulties, there is no feasible method for automatic con-trolling of bio-robots yet. In this paper, we propose a new method to realize the automatic navigation for bio-robots. A General Regression Neural Network (GRNN) is adopted to analyze and model the controlling procedure of human operations. Com-paring to the traditional approaches with explicit controlling rules, our algorithm learns the controlling process and imitates the decision-making of human-beings to steer the rat-robot automatically. In real-time navigation experiments, our method suc-cessfully controls bio-robots to follow given paths automatically and precisely. This work would be significant for future ap-plications of bio-robots and provide a new way to realize hybrid intelligent systems with artificial intelligence and natural biological intelligence combined together.

Natural materials such as bone, tooth and nacre achieve attractive properties through the “staggered structure”, which consists of stiff, parallel inclusions of large aspect ratio bonded together by a more ductile and tougher matrix. This seemingly simple structure displays sophisticated micromechanics which lead to unique combinations of stiffness, strength and toughness. In this article we modeled the staggered structure using finite elements and small Representative Volume Elements (RVEs) in order to explore microstructure-property relationships. Larger aspect ratio of inclusions results in greater stiffness and strength, and also significant amounts of energy dissipation provided the inclusions do not fracture in a brittle fashion. Interestingly the ends of the inclusions (the junctions) behave as crack-like features, generating theoretically infinite stresses in the adjacent inclusions. A fracture mechanics criterion was therefore used to predict the failure of the inclusions, which led to new insights into how the interfaces act as a “soft wrap” for the inclusions, completely shielding them from excessive stresses. The effect of statistics on the mechanics of the staggered structure was also assessed using larger scale RVEs. Variations in the microstructure did not change the modulus of the material, but slightly decreased the strength and significantly decreased the failure strain. This is explained by strain localization, which can in turn be delayed by incorporating waviness to the inclusions. In addition, we show that the columnar and random arrangements, displaying different deformation mechanisms, lead to similar overall properties. The guidelines presented in this study can be used to optimize the design of staggered synthetic composites to achieve  mechanical performances comparable to natural materials.

A video tracking system for measuring three-dimensional kinematics of a free-swimming fish is presented. The tracking is accomplished by simultaneously taking images from the ventral view and the lateral view of the fish with two cameras mounted on two computer-controlled and mutually orthogonal translation stages. Compared to the previous system we reported, the time resolution is greatly improved. A koi carp is selected for the experiment. By processing the images caught by the video tracking system, the three-dimensional kinematics of the koi carp during a continuous swimming containing several moderate maneuvers are obtained. In particular, the pitching motion of fish body and the tail motion, including lateral excursion, variation in tail height and torsion, are revealed for burst-and-coast swimming and turning maneuver. The error analysis is also provided for the measurement results.

During slow level flight of a pigeon, a caudal muscle involved in tail movement, the levator caudae pars vertebralis, is activated at a particular phase with the pectoralis wing muscle. Inspired by mechanisms for the control of stability in flying animals, especially the role of the tail in avian flight, we investigated how periodic tail motion linked to motion of the wings affects the longitudinal stability of ornithopter flight. This was achieved by using an integrative ornithopter flight simulator that included aeroelastic behaviour of the flexible wings and tail. Trim flight trajectories of the simulated ornithopter model were calculated by time integration of the nonlinear equations of a flexible multi-body dynamics coupled with a semi-empirical flapping-wing and tail aerodynamic models. The unique trim flight characteristics of ornithopter, Limit-Cycle Oscillation, were found under the sets of wingbeat frequency and tail elevation angle, and the appropriate phase angle of tail motion was determined by parameter studies minimizing the amplitude of the oscillations. The numerical simulation results show that tail actuation synchronized with wing motion suppresses the oscillation of body pitch angle over a wide range of wingbeat frequencies.

The viscous flow field around two-dimensional flapping (heaving and pitching) foils was numerically computed. The structural characteristics of caudal vortices were investigated and the contour curves at different phase angles were obtained. The relationships between the structural characteristics of the vortices and the force acting on the foil and between the widths of the caudal vortex street and of the caudal flow field were analyzed. A method to determine the shedding frequency of the vortices was proposed.