In this paper, an experimental analysis of overcoming obstacle in human walking is carried out by means of a motion capture system. In the experiment, the lower body of an adult human is divided into seven segments, and three markers are pasted to each segment with the aim to obtain moving trajectory and to calculate joint variation during walking. Moreover, kinematic data in terms of displacement, velocity and acceleration are acquired as well. In addition, ground reaction forces are measured using force sensors. Based on the experimental results, features of overcoming obstacle in human walking are ana-lyzed. Experimental results show that the reason which leads to smooth walking can be identified as that the human has slight movement in the vertical direction during walking; the reason that human locomotion uses gravity effectively can be identified as that feet rotate around the toe joints during toe-off phase aiming at using gravitational potential energy to provide propulsion for swing phase. Furthermore, both normal walking gait and obstacle overcoming gait are characterized in a form that can provide necessary knowledge and useful databases for the implementation of motion planning and gait planning towards overcoming obstacle for humanoid robots.

Cats are characterized by their excellent landing ability. During the landing, they extend and bend their flexible backs. This study was undertaken to examine the effect of flexible back on impact attenuation. We collected kinematic and ground reaction force data from cats performing self-initiated jump down at different heights. Based on these measurements, the mechanical energy and elastic back energy were calculated. Further, we derived a beam model to predict back stiffness from the morphology of the vertebral spines. We found that cat could actively modulate the bending level of flexible back and the landing angle at different heights, making some kinetic energy be stored briefly as elastic strain energy in the back. This mechanism allows cat to reduce the kinetic energy dissipated by limbs and improve the efficiency of energy absorption. These results can provide bio-logical inspiration for the design of a flexible spine on a landing robot, and we anticipated their use in the energy absorption equipments for planetary exploration.

Felines use their spinal column to increase their running speed at rapid locomotion performance. However, its motion profile behavior during fast gait locomotion has little attention. The goal of this study is to examine the relative spinal motion profile during two different galloping gait speeds. To understand this dynamic behavior trend, a dynamic motion of the feline animal (Felis catus domestica) was measured and analyzed by motion capture devices. Based on the experiments at two different galloping gaits, we observed a significant increase in speed (from 3.2 m•s−1 to 4.33 m•s−1) during the relative motion profile synchronization between the spinal (range: 118.86? to 168.00?) and pelvic segments (range: 46.35? to 91.13?) during the hindlimb stance phase (time interval: 0.495 s to 0.600 s). Based on this discovery, the relative angular speed profile was applied to understand the possibility that the role of the relative motion match during high speed locomotion generates bigger ground reaction force.

The aerodynamic role of the elytra during a beetle’s flapping motion is not well-elucidated, although it is well-recognized that the evolution of elytra has been a key in the success of coleopteran insects due to their protective function. An experimental study on wing kinematics reveals that for almost concurrent flapping with the hind wings, the flapping angle of the elytra is 5 times smaller than that of the hind wings. Then, we explore the aerodynamic forces on elytra in free forward flight with and without an effect of elytron-hind wing interaction by three-dimensional numerical simulation. The numerical results show that vertical force generated by the elytra without interaction is not sufficient to support even its own weight. However, the elytron-hind wing interaction improves the vertical force on the elytra up to 80%; thus, the total vertical force could fully support its own weight. The interaction slightly increases the vertical force on the hind wind by 6% as well.

Inspired by kangaroo’s locomotion, we report on developing a kangaroo-style hopping robot. Unlike bipeds, quadrupeds, or hexapods which alternate the legs for forward locomotion, the kangaroo uses both legs synchronously and generates the forward locomotion by continuous hopping behavior, and the tail actively balances the unwanted angular momentum generated by the leg motion. In this work, we generate the Center of Mass (CoM) locomotion of the robot based on the reduced-order Rolling Spring Loaded Inverted Pendulum (R-SLIP) model, for matching the dynamic behavior of the empirical robot legs. In order to compensate the possible body pitch variation, the robot is equipped with an active tail for pitch variation compensation, emulating the balance mechanism of a kangaroo. The robot is empirically built, and various design issues and strategies are addressed. Finally, the experimental evaluation is executed to validate the performance of the kangaroo-style robot with hopping locomotion.

In this paper a bio-inspired approach of velocity control for a quadruped robot running with a bounding gait on compliant legs is set up. The dynamic properties of a sagittal plane model of the robot are investigated. By analyzing the stable fixed points based on Poincare map, we find that the energy change of the system is the main source for forward velocity adjustment. Based on the analysis of the dynamics model of the robot, a new simple linear running controller is proposed using the energy control idea, which requires minimal task level feedback and only controls both the leg torque and ending impact angle. On the other hand, the functions of mammalian vestibular reflexes are discussed, and a reflex map between forward velocity and the pitch movement is built through statistical regression analysis. Finally, a velocity controller based on energy control and vestibular reflexes is built, which has the same structure as the mammalian nervous mechanism for body posture control. The new con-troller allows the robot to run autonomously without any other auxiliary equipment and exhibits good speed adjustment capa-bility. A series simulations and experiments were set to show the good movement agility, and the feasibility and validity of the robot system.

Recently, various kinds of biomimetic robots have been studied. Among these biomimetic robots, water-running robots that mimic the characteristics of basilisk lizards have received much attention. However, studies on the performance with respect to different geometric parameters and gaits have been lacking. To run on the surface of water, a water-running robot needs suffi-cient force with high stability to stay above the water. We experimentally measured the performance of the foot pads with different geometric parameters and with various gaits. We measured and analyzed the forces in the vertical direction and rolling angles of five different foot pad shapes: a circular shape, square shape, half-spherical shape, open half-cylinder shape, and closed half-cylinder shape. Additionally, the rolling stabilities of three kinds of gaits: biped, trotting, and tripod, were also empirically analyzed. The results of this research can be used as a guideline to design a stable water-running robot.

Exoskeletons are mechatronic devices used to increase human muscle strength and resistance. In the last decade these devices have become a very useful tool to assist active kinesiotherapy. This paper presents the design of exoskeleton focused on the rehabilitation of ankle and knee for the right leg. The construction of prototype like Exoskeleton for Lower Limb Training with Instrumented Orthoses (ELLTIO) using Series Elastic Actuator (SEA) to reduce the effort in the human joints, and a control law to perform a rehabilitation routine using an adaptive control scheme were first implemented in simulation to verify the control strategy and make a real rehabilitation test. The adaptive control law is proposed with the intention that the exoskeleton can adapt to user parameters at the time when performing the exercise. The results show the parameters estimation and tracking trajectory for the exoskeleton were proposed, and this trajectory could be a routine rehabilitation proposed by the therapist.

Titanium metals and its alloy have been widely used in hard tissue repairing fields due to their good biocampatibility and mechanical properties. However, bioinert response and biomaterial associated infections are the main problems for their clinical application. In this study, we chose titanium plates treated with anodic oxidation (AO-Ti), alkali-heat (AH-Ti) and acid-alkali (AA-Ti) methods, which have been proved to be bioactive in vivo, to culture with Staphylococcus aureus and Escherichia coli  to investigate the interaction between bioactive titanium surfaces and biofilm. We used X-ray diffraction (XRD), Scanning Electron Microscope (SEM), roughness measurement to study the physical-chemical properties of the as-received bioactive titanium surfaces, and Confocal Laser Scanning Microscope (CLSM) was employed to study the properties of biofilm formed on the biomaterial surfaces. The results indicate that the titanium surface subjected to anodic oxidation treatment is unfavorable for the formation of biofilm in vitro because the titania (TiO2) coating formed by anodizing has superior antimicrobial property than the other surfaces. Therefore, anodic oxidation surface modification is effective to endow titanium surface with bioactivity and antimicrobial property, which has the potential to improve the successful rate of the clinical application of titanium implants.

Biomimetic collagen/hydroxyapatite scaffolds have been prepared by microwave assisted co-titration of phosphorous acid-containing collagen solution and calcium hydroxide-containing solution. The resultant scaffolds have been characterised with respect to their mechanical properties, composition and microstructures. It was observed that the in situ precipitation process could combine collagen fibril formation and hydroxyapatite (HAp) formation in one process step. Collagen fibrils guided hydroxyapatite precipitation to form bone-mimic collagen/hydroxyapatite composite containing both intrafibrillar and interfibrillar hydroxyapatites. The mineral phase was determined as low crystalline calcium-deficient hydroxyapatite with calcium to phosphorus ratio (Ca/P) of 1.4. The obtained 1% (collagen/HAp = 75/25) scaffold has a porosity of 72%  and  a  mean pore  size of 69.4 µm. The incorporation of hydroxyapatite into collagen matrix improved the mechanical modulus of the scaffold significantly. This could be attributed to hydroxyapatite crystallites in collagen fibrils which restricted the deformation of the collagen fibril network, and the load transfer of the collagen to the higher modulus mineral component of the composite.

Bioactive calcium phosphate coatings were prepared on AZ91D magnesium alloy in phosphating solution in order to im-prove the corrosion resistance of the magnesium alloy in Simulated Body Fluid (SBF). The surface morphologies and compo-sitions of the calcium phosphate coatings deposited in the phosphating bath with different compositions were investigated by Scanning Electron Microscopy (SEM) with Energy Dispersive Spectrometer (EDS) and X-ray Diffraction (XRD). Results showed that the calcium phosphate coating was mainly composed of dicalcium phosphate dihydrate (CaHPO4•2H2O, DCPD), with Ca/P ratio of approximately 1:1. The corrosion resistance was evaluated by acid drop, electrochemical polarization, elec-trochemical impedance spectroscopy and immersion tests. The dense and uniform calcium phosphate coating obtained from the optimal phosphating bath can greatly decrease the corrosion rate and hydrogen evolution rate of AZ91D magnesium alloy in SBF.

In this study, the applicability of plasma nitriding treatment in the production of non-magnetic and corrosion resistant layer on 316L stainless steel implant material was investigated. 316L stainless steel substrates were plasma nitrided at temperatures of 350 ?C, 375 ?C, 400 ?C, 425 ?C and 450 ?C for 2 h in a gas mixture of 50% N2–50% H2, respectively. It was determined that the treatment temperature is the most important factor on the properties of the corrosion resistant layer of 316L stainless steel. The results show that s-phase formed at the temperatures under 400 ?C, and at the temperatures above 400 ?C, instead of s-phase, CrN and γ'-Fe4N phases were observed in the modified layer. The electrical resistivity and surface roughness of the modified layer increase with treatment temperature. Under 400 ?C the corrosion resistance increased with the temperature, above 400 ?C it decreased with the increase in treatment temperature. It was analyzed that the electrical resistivity and the soft (ideal) ferro-magnetic properties of 316L stainless steel increased with treatment temperature during nitriding treatment. Also, plasma ni-triding at low temperatures provided magnetic behavior close to the ideal untreated 316L stainless steel.

The present research aims to utilize the acrylic Core-Shell Rubber (CSR) particles to reduce the brittleness in Wood Plastic Composites (WPC) prepared from poly(lactic acid) (PLA) and rubber wood sawdust (Hevea brasiliensis). Experimental works consisted of two major parts. The first part concentrated on toughening PLA by using CSR particles. Mechanical tests revealed that PLA had become tougher with a more than five times increment in the impact strength when the CSR was added at only
5 wt%. The modified PLA was less stiff with the significant reductions of both elastic and flexural moduli and strengths. The second part focused on producing WPC from the toughened PLA and rubber wood sawdust. The tensile moduli and the strengths of the PLA composites increased with rubber wood content. The composites turned out to be more brittle with reductions of both the impact strength and the tensile elongation at break at all the sawdust contents. Toughening PLA/wood flour with 5 wt% CSR improved both the impact strength and the tensile elongation at break. The toughness enhancement was also depicted by the plastic deformation observed on the surfaces of fractured PLA/CSR/wood sawdust composites.

Currently, there are only three classical and a handful of emerging design methodologies available to structural engineers worldwide. None of these methodologies can explain the design concepts involved in the realization of natural structures such as trees, nor can they fully address the design needs of contemporary engineering structures. The recently developed Performance Control (PC) incorporates both the essence of the classical concepts and the newer procedures and addresses the observed performance of the structure during its known history of loading. PC attempts to mimic nature by applying the known theories of structures to the design of case-specific frameworks, rather than investigating their results for compliance against prescriptive criteria. Parametric examples have been provided to illustrate the applications of the conceptual design similarities between trees and manmade moment frames. It has been shown that an understanding of the structural performance of trees can enhance the structural design of moment frames, and that bioinspired PC can lead to minimum weight moment frames under lateral loading. The analogous performances of the natural and manmade structures may help explain the structural response of trees to similar loading scenarios.