A self-transfer aid robotic system is proposed for a patient with weak leg. By using the proposed robotic system, a patient can for example transfer between a wheelchair and a toilet by him or herself. This paper will present the principle of the robotic system and the user's human emotion.

View full abstract

This paper deals with a trajectory planning problem of a wheeled mobile robot under an obstracted environment where the robot is encountered with unforeseen obstacles and required to take a maneuvering motion. The robot is equipped with various sensors including soners, a laser range finder and a video camera. The robot creates a potential field on the fly when being encountered with a obstacle in order to generate a maneuvering motion. Also it will automatically detect occurrence of dead-lock situation and take an appropriate action to resolve the situation. In addition, the laser range finder is utilized to obtain extra information such as a sudden change of the ground continuity.

View full abstract

We participate in RoboCup competition using omnidirectional mobile robot with omnidirectional vision. In RoboCup environment, we assumed two goals as colored landmarks and implemented localization algorithms using omnidirectional images in two ways: with angle and distance and with angles only. We compared those algorithms by experiments and showed that experimental results are not always the same as mathematical solution. We also made numerical analysis of the localization algorithm for the evaluation of localization errors.

View full abstract

This paper investigates multiple mobile robots coordinating with each other under a potential conllision situation. The system considered consists of three wheeled mobile robots in which one of them serves as a leader agent and the rest follower agents. These robots are to collaboratively transport a large object. Uniqueness of our approach is mainly seen in the follower agents. Unlike conventional approaches, the followers in our method do not need to know the intention of the leader, e.g., where to go, in an explicit manner. Instead, the followers will assist the leader to accomplish the task as its own local task optimization. The efficacy of the proposed method is verified through simulation and experiments.

View full abstract

Recently, the safety of the robot to the collision with humans or objects is important. The report proposes the impulsive force reduction method for manipulator by using buffer materials and coupling inertia force. To verify our method, we measured the acceleration of manipulator's link at collision between a stand with a buffer material. As a result of the experiment, our method was effective in the extension of impact duration time and reduction of the acceleration at collision.

View full abstract

A body of humanoid robot is receiving a big reaction force during high-speed hand operation. The paper proposes a trajectory generation method by using redundant joint as counter weight. The method generates the trajectory with the changing from an initial trajectory in momentum space. The method, Modified Momentum Trajectory Generation, can be applied to reduce the reaction force and increase hand velocity.

View full abstract

In this study the method which generates the working plan of a dual manipulator system for robotic sheet metal bending is proposed. In work planning for robotic sheet metal bending, there are a lot of grasping position candidates and some re-grasping patterns is not one are possible. In work planning for robotic sheet metal bending, grasping position is determined using geometry of a sheet metal, re-grasping pattern is determined based on human bending operation. The each orbit of dual manipulators is determined by Repeated Direct Kinematics method, respected. Computer simulation is carried out based on the proposed method and illustrative examples and results of simulation are given. The effectiveness of this method is discussed.

View full abstract

We designed and developed an ankle-driven type quasi-passive dynamic walking machine by considering the possible application to orthosis with powered joint for the handicapped. We made considerations on stabilizing of walking from energy point of view. We calculated energy efficiency of this walking machine by two different evaluation methods from the literatures, and compared the results.

View full abstract

We designed and developed a quasi-passive dynamic walking robot with swinging torso, and we confirmed it can climb up a slope in a certain condition from some experiments. First, we made the strategy of climbing up slope of variable inclination angle. Next, we verified the validity of the strategy by experiments. Finally, we discussed on the treatment of contiguous/noncontiguous change of inclination angle.

View full abstract

In recent years, CPG (Central Pattern Generator)modelled on animals is attracting attentions as a suitable control technique for legged robots. The CPG network is considered to be effective to make the legged robot capable of adjusting its gait on uneven terrain. However, the CPG network requires a number of parameters to be decided for application. In this paper we propose a CPG network for a four legged robot, constructed a simulator to try out various combinations of parameters to find a suitable set, and show that with a certain set of parameters the proposed CPG network successfully generated satisfactly gait for the four legged robot.

View full abstract

Landing control of a humanoid robot is proposed to soften the shock when a robot jumped from a step. The designed actuator is using a cushion mechanism with a torsion spring between a motor and a gear. The rotation angle of the actuator is controlled by the output of a potentiometer attached to a robot joint.

View full abstract

A humanoid type biped robot with 12 DOF is proposed for university education. The proposed robot utilizes a multi-PIC Controller and I^2C communication system. This paper presents the study schedule for basic study, and the fabricated 12 DOF biped robot system.

View full abstract

In this study, we have tried to assemble small parts by using micro manipulator. In this case, it is necessity to inject binding material at narrow area (from 10μm to 0.1μm). This report discusses a pipetting device that can inject small quantities (from sub-pico liter to femt litter range) of binding material. Because the size of the micro pipette used to dispense is minute, the surface tension of the adhesive and the influence of the viscosity are very greatly related. Then we develop the pipetting device using the force of gravity by free fall, and experiment the performance of pipettes with different point angle. From experimental result, we obtain the relation between the point angle of pipette and the quantities of binding material.

View full abstract

The purpose of this research is to develop an under-actuated snake-like robot. There are many researches about snake-like robots. Many of snake-like robots require a lot of actuators corresponding to their joints. That may cause some negative effect such as increasing power consumption and complex control. In order to solve these problems, we propose a mechanism, the head joint of which is active and the other joints are passive. Namely there is only one active joint in our snake-like robot. The motion principle is quite simple ; the vibration generated by active joint is transmitted down to the tail link as a wave like motion. This paper shows that this simple mechanism can move foward, where we determine the parameters by experimental design.

View full abstract

The purpose of this research is to develop a new type of flapping robot. The wing of this flapping robot is two-pint-hinge-wing type. One hinge is an active joint (1st joint) at the shoulder, and the other hinge is a passive joint (2nd joint) at the elbow. The 2nd joint have a limitation of motion range and is driven by air resistance generated by flapping the 1st joint. There is no actuator at the second joint, thus it contributes to reduction of the weight. The tip wing is folded naturally when the root wing flaps up. Consequently the two-point-hinge-wing can also increase total lifting power by reducing negative lifting power. In order to increase total lifting power, we derive sub-optimal parameters: wing size and motion range. We also conduct verification by a basic experiment.

View full abstract

Although a joystick used in powered wheelchairs is widely used, some disabled are not able to manipulate the joystick. In this study, we have developed a noncontact-type operation interface for severe disabled people. This interface consists of a pointer which is set on a part of their body to be able to move voluntarily, and a control panel which has several windows to receive the infrared ray with digital modulation from the pointer. Each window pointed by the pointer is assigned a direction where to move the wheelchair. The wheelchair also has a safety device to prevent collision with obstacles by use of supersonic sensors.

View full abstract

The final goal of this study is to produce safety structures for the arms of robots for welfare. This paper describes a study on the control of load-displacement curves and the buckling/collapse behavior of skin cylinder cantilevers with various reinforcements and triggers. The peak load and the buckling/collapse behavior depend on the cross sections and the way of reinforcements. The mechanism of maintenance of load is also discussed. These results show that the skin cylinders with triggers have advantage in light weight and are available to safety structures for the diaper changing assistant robots.

View full abstract

The final goal of this study is to produce a safety structure for an arm of meal tray transportation robot. This paper describes an experimental study on the collapse and reversibility of a cantilever high-elastic circular tube with a trigger that is supported by round-shaped indenter at the end. The collapse and reversible behaviors depend on configuration of the tube and condition of the trigger. These results show that the load-displacement curve has a reversible behavior with a hysteresis loop and ideal load characteristic functions for the safety of meal tray transportation robot arm.

View full abstract

As a welfare equipment, a seated stairlift has been developed for senior citizen and physically handicapped person to go up and down stairs at home. The seated stairlift has two rails to keep the seating face horizontally by an automatic mechanism. If a seated stairlift with single rail can be developed, the price and the construction time can be reduced. In this research, we propose a robust control of the seated stairlift with single rail based on the system identification and H_∞ control theory. The effectiveness of the proposed method is shown by experiments.

View full abstract

We designed a rehabilitation unit for ankle and knee joint using pneumatic actuators. Joints are position controlled by allocating two actuators in an antagonistic way, and compliance is controlled by changing a air pressure of the actuators. We made experiments on changing compliance of the joint by using the simplified model of the rehabilitation unit, and confirmed the design policy.

View full abstract

We have performed basic experiments for the purpose of applying onomatopoeia to engineering problems. In these experiments, test subjects were made to perform lifting actions while listening to onomatopoeic utterances. We thereby demonstrated that there is a relationship between the onomatopoeic utterances and the lifting forces exerted by the test subjects. We examined how the lifting forces are related to the envelope of onomatopoeic utterances. Furthermore, we investigated how the lifting force is affected depending on whether or not emotion is expressed when uttering the onomatopoeia.

View full abstract

We have developed a Master-Slave Hand system to use rehabilitation field. This system has Haptic glove and Robot hand. Haptic glove has angle sensor to detect finger position and small balloons inside of the glove to present a force to user by compressed air. This glove makes it possible to give angle information of each finger to Slave hand system, and also to present the force, which is detected the slave hand to the user. To control this force, we use PWM control method to show the quantity of the force. We tried to use this glove Master-Slave Hand system, we could feel the slave hand force though haptic glove like areal force.

View full abstract

We developed a grasp assistance system, which can support gripping force for elderly people and also can do rehabilitation for their hand action. It is small and light system, it can attach to human hand directly. The drive mechanism consists of a bevel gear and an internal gear for MP joint, a wire and a torsion spring for PIP joint. We measurement the assisting force, it produced the assistance force enough for a practical use. And also we combined this mechanism in his hand and confirmed that this system can aid gripping action easily.

View full abstract

This paper describes about linear motion type displacement magnifying mechanism which is newly designed in order to obtain high magnifying rate with compact structure. Then, we tried to use it as a driving device for holding forceps. It was confirmed that the mechanism has functions sufficient for holding objects and the holding state can be monitored by sensing strains generated at its arms.

View full abstract

Recently, Japanese became accustomed to Western diet. Therefore, alimentary disease is increasing. Especially, it's important to detect colon polyp and the large intestine cancer early. The purpose of this research is development of small inspection robot, and it is an automatic round trip running in intestines. The movement method is an application of earthworm's expansion and contraction creeping type. The robot consists of the front or back holding parts and the expansion and contraction part at the center. The pneumatic devices are used for operation of robot. Each actuator is operated with the sequence control that uses MATLAB.

View full abstract

Recently, achievement the tele-medicine is attracting attention. It is regarded to realize redness of regional gaps of medical treatment, reduction of patient's incidence, efficiency improvement of medical treatment etc. We are developing the robot system for tele-ultrasound imaging diagnosis. This system consists of the master-slave robot system in order to use probes of the ultrasound diagnostic equipment for telemedicine. This paper reports about a development of the master robot and remote control the slave robot. Moreover, it reports that the ultrasound imaging was acquired by a remote-controlled experiment through LAN.

View full abstract

This study examined a time driver needs to adapt to characteristic of vehicle after assisted steering is changed to manual steering. The experiment used a driving simulator. The level of driver's involvement in driving (the concerned level) was "Holding a steering wheel and front gazing (Pattern A)" and "Not holding a steering wheel and not front gazing (Pattern B)". The experimental condition was "lane change" and "side wind". As a result, in the case of Pattern A, driver needs 1 second to adapt to characteristic of vehicle in lane changing and 3 seconds in side wind. In the case of Pattern B, driver needs 2 seconds to adapt to it in lane changing and 3 seconds in side wind.

View full abstract

To arbitrarily present virtual texture through vibrotactile display, effects of frequency composition of vibration on intensity and sensation of texture was examined with regard to four frequency channels of human's vibrotactile receiving system. As a result, intensity of compound stimulus of two sinusoidal vibration was influenced strongly by higher frequency portion. About sensation of texture, the results showed that feeling of roughness and sharpness has the closest relationship with frequency. In addition, it was shown that sensation of complexity and density can be affected by changing stimulated channel of human's vibrotactile receiving system.

View full abstract

The authors considered that the human physiological signals were important for healthcare because they are not voluntary, and they indicate the human body and mental condition. Therefore, the objective of this paper is to measure and analyze the human physiological signals in daily life with noninvasive way. In this paper, we measured the physiological signals such as heat flux, skin temperature and GSR for 145 days with a wearable sensor, SenseWear Pro_2 Armband. Then, we confirmed a peak signal which was 13.2 times stronger than the noise signal at 24 hours cycle (1.16*10^<-6>[Hz]) in heat flux through the frequency analysis.

View full abstract

A compact perfusion system with oscillatory flow was developed for bone tissue engineering, and its seeding and culture effects were evaluated in present study. Mouse osteoblast-like cells, MC 3T3-E1, were seeded and cultured for 6 days in porous ceramic scaffolds by either static or oscillatory perfusion method. Compared with static culture, the oscillatory perfusional method showed significantly higher seeding efficiency and higher scaffold cellulary by DNA content analysis, as well as higher ALP activity and after 6 days of culture. Stereomicroscopy observation of MTT staining and Hoechst/PI double staining also demonstrated homogeneous seeding, proliferation and viability spatially in oscillatory system ; on contrast, static culture showed a polarized seeding and proliferation favoring only the outer and upper surface, with cells in central part of scaffold underwent apoptosis. The results demonstrated the novel oscillatory perfusion system could be a simple but useful bioreactor for bone tissue engineering with easier operation.

View full abstract

Knowledge on cell disruption by physical stresses is applicable to material introduction and sterilization, etc. In this study, the influences of various physical stresses on E. coli cells were evaluated. Cell viability decreased according to strength and loading time of physical stresses examined, i.e. shear stress, ultrasonic and pressure change. The quality of cell disruption, observed by scanning electron microscopy, differed between these physical stresses. The quantity of water-soluble protein spilled out from cells after loading of stresses increased with concomitant decreasing in cell viability. These results suggest that the disruption of E. coli cells by loading of stresses accompanied with outflow of cytoplasm. Insertion of relaxation time elongated cell viability. These results are discussed in application point of view.

View full abstract

Several type of endoscope was developed for MIS (Minimally Invasive Surgery). This paper reports our efforts to develop endoscope with high degree-of-freedom. The paper presents three type of endoscope. Model A ; driving with gear and motor inside. Model B: driving with independence. Model C: driving with solidarity. Experiments were held to evaluate dexterity and mechanics with four parameters: bending angle, velocity of angle, theory and limited angle. The velocity of motor of model A is 70step/s. and others are 5step/s. the acceleration and deceleration of all model are 100000step/s. It resulted that model A shows most effective motion, but considered inner space of endoscope, type B is truly effective. Motion of Type C is not standard interval. But it's motion is sufficiently. it concluded model B is effective.

View full abstract

Micro-bubbles are very small air bubbles with diameters of the order of less than several tens microns and have become to attract people's concerns rapidly in the past several years due to their wide potential in practical applications to a variety of advanced technologies. Their generating technologies are also splendidly developed. However, complex device and high power supply are required for conventional micro-bubble generators. In this study, the compact and low power micro-bubble generator has been developed. In order to verify the applicability of purification system, experiments were conducted by changing the pH levels (pH:5 (acid), pH:7 (neutral), pH:9 (alkaline)) in the initial condition. The pH level approaches to neutral value after the micro-bubble generation for all cases.

View full abstract

Micro-bubble (MB) is now collecting many interests in a variety of fields. But, theoretical explanation of special effects on MB is hardly adequate. In this paper, we tried the theoretical simulation about shrinking process of a spherical rising air-bubble in water. Moreover, we proved the validity on the assumption of the steadiness of flow around bubble. This simulation result shows that the impulse occurring on the collapse of cavitation-bubble cannot appear in the case of natural MB.

View full abstract

HIFU (High Intensity Focused Ultrasound) treatment combined with microbubbles as a heat transducer has currently been investigated. It has been indicated that microbubbles have a potential to enhance the heat deposition around the focal region of ultrasound. In order to realize this method, it is needed that the coagulation region in the tissue which contains microbubbles is well-controlled. In this study, the temperature distribution in the medium with microbubbles is analyzed in detail. This time, a thermal liquid crystal (TLC) sheet is used for the measurement of temperature distribution in a polyacrylamide gel. In the case of no bubbles, the shape of the high temperature region was ellipse. In the case of some bubbles, the shape grew more complicated and its area became larger. The microbubbles radiate heat energy around them, and the attenuation effect of ultrasound becomes larger. In the case of too many bubbles, the temperature at the geometric focus didn't become so high. The bubbles shield the most of ultrasound energy. It is very important to choose the optimal conditions of microbubble-enhanced HIFU treatment, considering these phenomena.

View full abstract

Jets issuing through small holes in a wall into a freestream have proven effective in the control of flow separation. This technique is known as the vortex generator jet method (VGJ). If a precursor signal of separation is found, the separation control system using VGJ can be operated just before the onset of separation. Therefore, flow field with no separation is always attained. In this study, we measured the flow field and the wall static pressure in a two-dimensional diffuser. Flow separation occurs when the divergence angle reaches at 18 degrees. The streamwise velocity measurements were carried out in the separated shear layer and the spectral analysis was applied to the velocity fluctuations at some angle of diffuser. The pattern of peak in the spectral analysis is changed as the divergence angle increases over 18 degrees due to the enhancement of the growth of the shear layer vortices.

View full abstract

Experimental study was carried out on the vortex breakdown in a cylindrical container with free surface. Swirling flow was driven by the rotation of the bottom endwall disk. Meridional flow was visualized by means of the fluorescein sodium dye technique. Various formations of one axis bubble, two axis bubbles, one axis bubble attached to the free surface, two axis bubbles with the upstream one attached to the free surface, ring vortex etc. were observed. Critical boundaries for various type vortex breakdowns and boundary between steady and unsteady flows were also shown for the combination of Reynolds number based on the rotation of the bottom endwall and the aspect ratio of the depth of working fluid to the radius of the container. Comparison with the previous experimental and numerical results is discussed.

View full abstract

An experimental study has been performed to investigate the radial flow phenomena in a disk-shape channel which simulate a gas flow in a disk-shape planar-type Solid Oxide Fuel Cell (SOFC). In the planar-type SOFC, a reduction of thermal stress is one of the important issues. A temperature distribution in the planar-type SOFC is strongly affected by the gas flow behavior, and hence we tried to clarify flow pattern at various mass flow rate by using of particle image velocimetry (PIV). In the present study, it was found that a uniform flow distribution in the fuel channel was attained in the case of Reynolds number of 4 to 7. On the other hand, non-uniform flow distribution was enlarged with increase of flow rate in the air channel. These results suggest the optimum flow conditions expected in the disk-shape SOFC.

View full abstract

The paper describes the results of experimental investigation of underexpanded jet impinging on a plate. When the pressure ratio across the convergent nozzle exceeds the critical value (1.893 for air), the jet becomes underexpanded. The jet is not uniform due to the presence of the expansion wave, the compression wave and the shock wave in it. This flow field is often observed in the assist gas of laser cutting, the exhaust jet of STOVL aircraft and rocket. When the flat plate is placed in this flow field, the strong wave called "plate shock" appears near the flat plate. The fluid that passes through the plate shock moves at subsonic speed toward the flat plate, and then spreads over the plate as its speed increases, where the wall jet forms. The schlierenphotography and shadowphotography are used to visualize the flow field. In this experiment the angle between the plate and the jet axis is changed, and the flow filed is observed. The results were compared with each other for different angles.

View full abstract

Numerical code for using unstructured meshes composed of hybrid elements was developed. In this study, numerical analysis of flow in the evaporator, which is a multi-branch ducts, was performed by using the code developed. As the header and the branch-pipes addressed in this study were duct of circular cross-section, hexahedral elements, therefore, were used near the wall in order to adapt mesh to the configuration. In the region far from the wall, tetrahedral elements were used and pyramid elements were used to connect hexahedral and tetrahedral elements. The governing equations are discretized by the finite element method using a stabilising scheme, the characteristic-Galerkin method. The calculated results obtained by the code developed, including velocity vectors and flow rates to each branch, are shown.

View full abstract

The purpose of this study is to make clear the physical mechanism of the drag reduction of square cylinders. Besides, we focus on the depth of grooves. Experimental investigations on the flow around square cylinders ware carried out in the range of 4.5×10^4≦Re≦5. 5×10^4. From these results, It becomes clear that drag coefficients become low, about 50% from the square cylinder, in the case of the 7.5% depth of grooves. Moreover, we were able to identify the compound effect by corner-cuts and grooves. In contrast, in the case of the 2.5% and 5.0% depth, drag coefficients were not changed.

View full abstract

The vortex generator jet method is an active control of flow separation and can achieve the adaptive control by properly adjusting the jet speed. It is important to control flow separation effectively that the details of near fields of the jet are clarified for issuing the jet into a crossflow. For the vortex generator jets, the suppression of flow separation is affected by the jet orifice shape. In this study, structural features resulting from the interaction of a non-circular jet issuing transversely into a crossflow are described with the help of flow visualization technique and hot-wire anemometry. The formation and behavior of the vortices in the wake were affected by the jet orifice shape. The velocity measurements were carried out in the wake during one cycle of the wake vortex passing through the measurement position. The increment of the vertical velocity was observed in the wake and the weak momentum near the lower wall was transported to the main flow by the wake vortex.

View full abstract

The high-speed pulsating flow is found in the exhaust system of the reciprocating internal combustion engine, the piping system connected to reciprocating compressor, etc., and has various features which never exist in the steady flow. This work is concerned with an experimental study of the high-speed pulsating flow in a straight pipe and the jet discharged by the pipe. The behavior of small vortices along the boundary of the discharged jet was observed. It is found that the occurrence of shock wave and the shape of the vortex ring are dependent on the frequency of pulsation. In particular, the shape of the vortex ring depends greatly on whether the shock forms in the pipe or not.

View full abstract

Cu films were annealed after surface diffusion of Cu-P alloy to Cu, to development the spring materials which reserved internal electrical resistance with high surface strength, Cu films were diffusion treated after Cu-P deposition. Spring recovery rate were increased with increasing the diffusing temperature (over 0.5Tm) and diffusion time. From the aspect of electrical resistance, it has succeed to keep the value 1/2 compared to that of Ni which is already in practical use.

View full abstract

This paper deals with a stress concentration problem of an elastic circular solid cylinder with an elastic spherical inclusion under tension. Effects of Poisson's ratio, especially effects of negative Poisson's ratio, on the stress concentrations are investigated. Lakes has shown that there are materials with negative Poisson's ratios. A method of solution is presented for the problem by applying Green's functions for axisymmetric body force problems of infinite circular solid cylinder and fundamental solutions for axisymmetric problems of elasticity.

View full abstract

Carbon nanotubes have many attractive properties. Since experiments on the mechanical properties of carbon nanotubes are difficult because of their nanoscale sizes, numerical simulations are essential to their analysis. In this paper, we investigate the mechanical properties of carbon nanotubes by molecular dynamics simulation employing the second generation reactive empirical bond order (REBO) potential. We compute the Young's modulus of carbon nanotubes with various lengths. We show that the Young's modulus of carbon nanotubes depends on the length of tubes and the elongation speed.

View full abstract

Delayed fractures in carbon-fiber-reinforced polymer matrix composites could be observed even at room temperature due to an accumulation of micromechanical damages, such as interfacial debondings or fiber breaks. In this study, the creep-rupture time of unidirectional composites consisting of carbon fiber and vinylester resin is predicted under consideration of the progress of interfacial debonding, which corresponds to an increase of stress recovery length, and which is accompanied by a fiber break. The time-dependent rupture strain of unidirectional composites is calculated based on the global load sharing theory, which takes into account an increase of the stress recovery length, which is determined using carbon/vinylester single-fiber composite. The creep rupture time of unidirectional composites is formulated, and the prediction of the time-dependent rupture strain decrease are verified by a comparison between the residual strength of the unidirectional composite after a fixed displacement test and the calculated results at that condition.

View full abstract

This paper studies the effects of edge stitching on tensile fatigue properties of CFRP laminates. Fatigue damage development was investigated through experimental observation. From experimental observation results, it was shown that introduction of the stitch threads suppressed the initiation and propergation of the delamination. But the stitch thread broke in earlier stage under the high stress level cyclic loading. As a result, fatigue lives of the stitched laminates were shorter than that of the unstitched laminates. On the other hand, it was remarkable that the fatigue lives between the both laminates were almost equal due to the difference of internal damage propergation.

View full abstract