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 kinematic model.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 conditions that maintain the position of the contacted feet on the surface.So the method has an advantage for analyzing the climbing motion of the quadruped mechanism in a real time application.The kinematic model of a gecko consists of four legs based on 7-degrees of freedom spherical-revolute-spherical joints and two revolute joints in the waist.The motion of the kinematic model is simulated based on measurement data of each joint.The motion of the kinematic model simulates the investigated real gecko's motion by using the experimental results.The analysis solves the forward kinematics by considering the model as a combination of 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 other gaits are simulated based on the kinematic model.The maximum strides of each gait are calculated by workspace analysis.The result can be used in biomimetic robot design and motion planning.

Design and implementation of digital content metadata system

Today's multimedia services are far beyond just the voice and data services:they have been diversified tremendously after fueled by the advancement of network infrastructures as well as the sudden surge of multimedia data itself.Currently,researches on metadata insertion,management and transfer keep going very well in order to provide a variety of services to users.In this paper,we propose the design and implementation methods of digital contents metadata system for insertion,storage and retrieval of metadata.The performance evaluation shows that the proposed method performs better than the existing method.

Empirical Study on Shapes of the Foot Pad and Walking Gaits for Water-Running Robots

Recently, various kinds ofbiomimetic 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.

Hexapedal Robotic Platform for Amphibious Locomotion on Ground and Water Surface

Bio-inspiration is a starting point from which to design engineering products by learning the secrets of living creatures. We present the design, analysis, and experimental results of a robotic platform inspired by the basilisk lizard, which is well known for its ability to run on water surface. The goal is to develop a robotic platform for amphibious locomotion on ground and water using a single configuration. A tripod gait is achieved with a hexapedal configuration and four-bar-based repeated motion of the legs. The hexapedal configuration is empirically proven to have an advantage in terms of rolling stability on water. On ground, the tripod gait can satisfy the requirements of static stability to make the center of gravity and center of pressure occur at the same position. The footpad design was determined based on an empirical study of the rolling stability and lifting force. The theoretical background and experimental results are presented to validate the ability of the proposed design to run on water and on the ground.

Structural color switching with a doped indium-gallium-zinc-oxide semiconductor

Structural coloration techniques have improved display science due to their high durability in terms of resistance to bleaching and abrasion,and low energy consumption.Here,we propose and demonstrate an all-solid-state,large-area,lithography-free color filter that can switch structural color based on a doped semiconductor.Particularly,an indium-gallium-zinc-oxide(IGZO)thin film is used as a passive index-changing layer.The refractive index of the IGZO layer is tuned by controlling the charge carrier concentration;a hydrogen plasma treatment is used to control the conductivity of the IGZO layer.In this paper,we verify the color modulation using finite difference time domain simulations and experiments.The IGZO-based color filter technology proposed in this study will pave the way for charge-controlled tunable color filters displaying a wide gamut of colors on demand.

Analysis and Experiment on the Steering Control of a Water-running Robot Using Hydrodynamic Forces

Steering is important for the high maneuverability of mobile robots. Many studies have been performed to improve the maneuverability using a tail. The aim of this research was to verify the performance of a water-running robot steering on water using a tail. Kinematic analysis was performed for the leg mechanism and the interaction forces between the water and the feet to calculate the propulsive drag force of the water. This paper suggests a simplified planar two-link rigid body model to determine the dynamic performance of the robotic platform with respect to the effect of the tail＇s motion. Simulations based on a dynamic model were performed by applying a range of motions to the tail. In addition, a simulation with a Bang-bang controller was also performed to control the main frame＇s yawing locomotion. Finally, an experiment was conducted with the controller, and the simulation and experimental results were compared. These results can be used as a guideline to develop a steerable water-running robot.

Experimental Study on Drag-induced Balancing via a Static Tail for Water-running Robots

Robotics is one area of research in which bio-inspiration is an effective way to design a system by investigating the working principles of nature. Recently, tails have received interest in robotics to increase stability and maneuverability. In this study, we investigated the effectiveness of a static tail for bio-inspired water-running locomotion. The tail was added to increase the stability in the rolling and yawing directions based on the hydrodynamic force from interaction between the tail and the water. The drag coefficient in the interaction is not easy to calculate analytically, so experimental studies were done for various static tail shapes. Five different shapes and compliances in two directions were considered for experimental design candidates. The result was applied to design a stable amphibious robot that can run on ground and water surfaces.

The Parametric Study on the Development of the Large-Scale Coherent Structures in a Mixing Layer

The theoretical investigation of the role of three-dimensional large-scale coherent structures and their mutual interactions in a developing plane mixing layer subjected to external forcing is presented. Large-scale coherent structures are decomposed into 3 fundamental and 2 subharmoic wave modes. A parametric study is carried out examining effects of a multitude of initial conditions. It is found that the evolution of the forced three-dimensional shear layer and the associated local entrainment can be influenced greatly by the initial amplitudes and phases of the large-scale modes. The presence of three-dimensional modes may have a profound effect on shear layer growth when forced at amplitudes comparable or larger than those of the two-dimensional ones. This effect is more pronounced at low frequency. Nonlinear interactions between the fundamentals and subharmonics indicate that subharmonics of the most amplified frequency of the shear layer are usually produced during the early stages of flow development, while its harmonics are always produced far downstream, regardless of initial conditions. The results of this study provide useful parametric information for the control, through multi-mode forcing, of shear layers in practical applications, aiming at mixing and transport augmentation.

Parametric Study on Design Parameters of Water-running Robot Based on Dynamic Simulation

There are many design parameters to determine a performance of a robot. Especially, in the case of the mobile robots, they requirc complicated motion at various environments to get high performances. In this sense, the analysis of the design parameters is the most important work to design an efficient mobile robot. In this study, we analyze the design parameters for the water-running robot. From the parametric study, we find some solutions to improve the performances of the robot. We derive dynamic equations for the water-running motion, and do a sensitivity analysis to understand the relationships between the parameters （frequency of the leg, stiffness of torsional springs that connects multi frames and mass of frames） and the performance of the water-running motion such as running speed and pitching stability. We use an orthogonal array to make various combinations of the parameters, and to reduce the number of a simulation process. As results, we summarize some solutions to improve the water-running motion. We are expecting that this study is going to be used to design robots that are operated on the water.

INFLUENCE OF LARGE-SCALE VORTICAL STRUCTURES ON THE PARTICLE DISPERSION IN A PLANE MIXING LAYER

The present study considers the developing mixing layer that is formed bymerging of two free streams initially separated by a splitter plate. To investigate the influence ofthe vortical structures on the particle dispersion, numerical simulation was conducted when thevelocity ratio, defined as R = U_∞ - U_(-∞)/U_∞ + U_(-∞), is 0. 5. Large-Eddy Simulation (LES)was employed to understand the effect of large-scale vortical structures originated by theKelvin-Helmholtz instability on the partical dispersion. The flyash with the particle sizes 10, 50,100, 150, and 200um respectively were loaded at the origin of the two-dimensional mixing layer. Itis confirmed that the particle dispersion depends strongly on the motion of large-scale vorticalstructures. The particle dispersion is visualized numerically by following the particle trajectoriesin the mixing layer undergoing pairing interaction.