TRANSACTIONS OF THE JAPAN SOCIETY OF MECHANICAL ENGINEERS Series C
Online ISSN : 1884-8354
ISSN-L : 1884-8354
Volume 78, Issue 792
Displaying 1-32 of 32 articles from this issue
Mechanical Systems
Regular Paper
  • Hiroki MORI, Takuo NAGAMINE, Ryo ITO, Yuichi SATO
    2012 Volume 78 Issue 792 Pages 2720-2732
    Published: 2012
    Released on J-STAGE: August 25, 2012
    JOURNAL FREE ACCESS
    This paper describes experimental and analytical study on the behavior of a falling water sheet. The observation of water sheet displacement and air pressure variation in the chamber implies that one of the causes of oscillation is downward squeeze action of a water sheet on an air chamber. We propose a simplified analytical model. Analytical results agree well with experimental ones. Further analytical results explain the occurrence of multiple modes of oscillation in a condition. In addition, we explain the instability mechanism using the work done by a falling water sheet on an enclosed chamber.
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  • Taichi MATSUOKA, Tetsuya TAKABE, Yujiro AKUTA, Nobuhiro WAKABAYASHI, K ...
    2012 Volume 78 Issue 792 Pages 2733-2745
    Published: 2012
    Released on J-STAGE: August 25, 2012
    JOURNAL FREE ACCESS
    Dynamic absorbers are widely used for suppressing the vibrations of beam-like structures such as skyscrapers and long bridges due to an earthquake or strong wind. These dynamic absorbers utilize the shearing force that they exert on beam-like structures (they are defined as shearing-type dynamic absorbers). In this paper, the authors propose a new type of dynamic absorber utilizing the bending moment that it exerts on a beam (it is defined as a moment-type dynamic absorber). The frequency responses of a cantilever and simply supported beams to which a moment-type dynamic absorber is attached, and tuning conditions of the dynamic absorber are discussed theoretically and numerically. Trial moment-type dynamic absorbers were made using three-layered sandwich beams and auxiliary masses. The dynamic absorbers, which approximately satisfy the optimum conditions for the first mode of a cantilever and simply supported beams, were attached to the beams, and the effects of vibration suppression of the dynamic absorbers were measured using an electromagnetic vibration machine. The experimental results showed that the moment-type dynamic absorber is more effective than the shearing-type dynamic absorber for suppressing the vibration of the beams. The experimental results were compared with the calculated results, and the propriety of the calculations was confirmed.
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  • Kazunori YAGI, Shigeo KOTAKE, Takahiro KAWAMURA, Yasuyuki SUZUKI
    2012 Volume 78 Issue 792 Pages 2746-2759
    Published: 2012
    Released on J-STAGE: August 25, 2012
    JOURNAL FREE ACCESS
    In this study we design a multiple cantilever for an atomic force microscope (AFM) under tapping mode as three-body vibro-impacts oscillators based on Grover wave algorithm. Static vibro-impact oscillations are derived by modifying Grover algorithm with damping and an exciting operators to express piecewise linear vibrations. We obtain the condition of steady state under tapping mode in AFM cantilever from the algorithm. Instabilities of the static oscillation caused by sudden change of the impact position is analyzed by numerical calculations. Within a small deviation, the system will converge with the steady states. The system shows better robustness from disturbance with a smaller reflection coefficient and larger collision speed. Also it is shown that the impact velocity of cantilever can be controlled by changing the amount of excitation. Moreover, since the amplitude of non-impact oscillator can be larger than that of impact one in case of small mass ratio. γ<1, vertical resolution of AFM can be improved by using the cantilever.
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  • Yutaka YOSHITAKE, Ryosuke SHIMIZU, Fumitaka SHIBAHARA, Shuhei KAJIHARA ...
    2012 Volume 78 Issue 792 Pages 2760-2770
    Published: 2012
    Released on J-STAGE: August 25, 2012
    JOURNAL FREE ACCESS
    This paper deals with the vibration quenching of mechanical structures using a Hula-Hoop. Quenching of vertical vibration of the one-degree-of-freedom system forced by centrifugal force is compared with that of horizontal one. Following was made clear from the numerical analysis: (1) The device using Hula-Hoop is very effective for not only horizontal vibration quenching but also vertical one in the region exceeding the resonant frequency. (2) On the vibration quenching problem in the vertical vibration, if there is the parametric excitation relation between the Hula-Hoop and the main system, the Hula-Hoop moves as pendulum in the region near resonance frequency and quenching the main system is possible. However, if the mass of Hula-Hoop is light, the quenching by autoparametric excitation is not enough. (3) The smaller the damping of the hula-hoop is, the more the vibration of main system is quenched. (4) In the vibration quenching problem using Hula-Hoop, the larger the mass of the Hula-Hoop is, or the longer the length between rotational center and gravity center of the Hula-Hoop is, the more effective the Hula-Hoop is. (5) It is suggested that the system with essentially large unbalance may be quenched in large frequency region using autoparametric excitation and rotation of Hula-Hoop.
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  • Feng SUN, Koichi OKA
    2012 Volume 78 Issue 792 Pages 2771-2780
    Published: 2012
    Released on J-STAGE: August 25, 2012
    JOURNAL FREE ACCESS
    This paper proposes a simultaneous suspension of two iron balls using a variable flux path control mechanism. This mechanism consists of a disk-type permanent magnet, a rotary actuator, and two iron cores. In this mechanism, the two iron balls are suspended in parallel. The suspension forces for two iron balls are generated on the ends of two iron cores, and controlled by varying the angle of the disk magnet that is driven by a rotary actuator. In this paper, first, the control principle of suspension force is explained, and the experimental prototype and the controller are introduced. Second, basing on experimental data, a numerical model is setup, and the controllability is proved. Finally, the feedback gains are calculated by LQR (Linear Quadratic Regulator), and the simultaneous suspension experiment of two iron balls is succeeded with the linear rails. All results indicate that the two iron balls can be suspended simultaneously.
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  • Susumu HARA, Tsubasa WATANABE, Yohei KUSHIDA, Masatsugu OTSUKI, Yoji Y ...
    2012 Volume 78 Issue 792 Pages 2781-2796
    Published: 2012
    Released on J-STAGE: August 25, 2012
    JOURNAL FREE ACCESS
    This paper discusses landing response control methods of planetary exploration spacecrafts on the basis of momentum exchange principles. Concretely, the methods adopt momentum exchange impact dampers (MEIDs) that absorb the controlled object's momentum with extra masses close to the object (damper masses). For example, this paper shows Upper-MEID (U-MEID) that launches the damper mass upward and Lower-MEID (L-MEID) that drops the damper mass downward. Moreover, Generalized-MEID (G-MEID) consisting of U-MEID and L-MEID is introduced. The optimal design parameters of the G-MEID mechanism in a single-axis case for the landing of a spacecraft are investigated. Simulation investigation verifies that the G-MEID mechanism is superior than any other MEID mechanisms from the point of view of reduction of the maximum rebound of the spacecraft. Moreover, the effectiveness of the G-MEID whose U-MEID adopts an active actuator (G-Hybrid MEID) is verified in the view of the rebound reduction performance and the robustness against the landing ground stiffness and spacecraft's mass variations.
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  • Ikko MATSUBA, Shun USHIDA, Hiroshi OKU
    2012 Volume 78 Issue 792 Pages 2797-2807
    Published: 2012
    Released on J-STAGE: August 25, 2012
    JOURNAL FREE ACCESS
    This paper reports the experimental results of the dynamic modelling using MIMO closed-loop system identification, controller design and implementation for hovering flight of a radiocontrolled helicopter. The helicopter is set on our handcrafted supporting device, and it has the roll, side-to-side and up-and-down motions that controlled by the aileron and the throttle. Several dynamic models with defferent orders are derived from closed-loop system identification experiments with the MOESP-type closed-loop subspace model identification method (CL-MOESP). Then, we compared their model with the real system, and LQR with a full state observer is designed and implemented.
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  • Kentaro TAKAGI, Yasutaka YAMADA, Tsuyoshi INOUE
    2012 Volume 78 Issue 792 Pages 2808-2823
    Published: 2012
    Released on J-STAGE: August 25, 2012
    JOURNAL FREE ACCESS
    A sensorless parameter estimation method for piezoelectric structures is proposed. Compared with the conventional method, this paper introduces a lossy electrical model that takes the internal resistance of piezoelectric structures into consideration. A new electrical impedance transfer function for piezoelectric structures is obtained. Parameter estimation method using linear and nonlinear frequency-domain least squares methods are discussed only based on impedance measurement. In the experiment for estimating parameters, the electrical impedance of the piezoelectric element is highly affected by the relative humidity. It is verified that the frequency response of the identified model shows a good agreement with that of the measured impedance, in contrast to that the conventional model could not perform accurate estimation. The accuracy of the estimated parameters are also investigated by damping experiments with a tuned LR shunt circuit.
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  • Masao KINOSHITA, Masaki EBINA, Masataka OHSAWA, Ryoichi HIBINO, Hiroak ...
    2012 Volume 78 Issue 792 Pages 2824-2836
    Published: 2012
    Released on J-STAGE: August 25, 2012
    JOURNAL FREE ACCESS
    This paper discusses a research on 2-dimensionl visualization of a spot weld piece using laser-ultrasonic technique. This laser-ultrasonic apparatus can scan a surface on a weld piece, and get ultrasonic longitudinal signals on several hundred measurement points per 10mm order. We analyzed these signals by Frequency Response Characteristic from 10MHz to 100MHz, and showed that the ultrasonic attenuation was related to the gain, and the ultrasonic propagation velocity was related to the phase, for frequency domain spectrum. At result, it was appeared that the gain of nugget parts was less than the gain of parents, and the phase of HAZ was latter than the phase of parents and nuggets. From these results, we made maps on frequency domain spectrum, and could realize to visualize the parent and the nugget, the HAZ on a weld piece. In addition, using Electron Back Scatter Diffraction, it was shown that the gain was effected by the crystal diameters, the phase was effected by the crystal directions.
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  • Junji YOSHIDA, Nobuyuki KAWAGOE, Tomohiro KAWAMURA
    2012 Volume 78 Issue 792 Pages 2837-2847
    Published: 2012
    Released on J-STAGE: August 25, 2012
    JOURNAL FREE ACCESS
    Bicycle is a popular vehicle for general public because of the low price and the easy maintenance, and will be more importance vehicle by the low environmental loading in the future. Improvement of bicycle ride comfort is one of important factors to increase the popularity. In this study, subjective evaluation test and reduction of bicycle vibration were performed to improve it. In the subjective evaluation, low frequency seat vibration was found to affect the ride comfort very much. Subsequently, transfer path analysis (TPA) and hammering test were performed to obtain vibration characteristic of the bicycle for reduction of the seat vibration. Through TPA, rear frame of the bicycle was found to have high influence to seat vibration than that of front side and the vibration behavior was obtained by modal analysis. For reduction of the seat vibration, a spring was inserted to the front of the seat and steel plates were attached to rear frame to increase the stiffness. As a result, the acceleration level at running condition was decreased about 10 dB by the modification, and the ride comfort was improved so much.
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  • Yasuhiro MINAMIYAMA, Takanori KIYOTA, Noboru SUGIMOTO
    2012 Volume 78 Issue 792 Pages 2848-2859
    Published: 2012
    Released on J-STAGE: August 25, 2012
    JOURNAL FREE ACCESS
    Passive dynamic control (“PDC”) is a mechanical system control method based on an inherently safe design using a braking mechanism effectively. In this paper, follow-up control of pneumatic cylinders using PDC is described. Because conventional control methods using only an actuator do not have a stopping mechanism, it is difficult to prevent the controlled object from deviating from the target trajectory. On the other hand, PDC can prevent deviations of the controlled object, and return it to the target trajectory. Since this control was developed with an image of enclosing the controlled object to the target trajectory by gradually narrowing the wide area around the target trajectory, it is referred to as “enclosing control”. An experimental setup using two PDC pneumatic cylinders equipped with electromagnetic friction brakes and load cells was developed. The effectiveness of the enclosing control method is verified through experiments of follow-up control for a circular trajectory and compared with PI control. In addition, the enclosing control method is applied to follow-up control for a straight line trajectory.
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  • Nagayoshi KASASHIMA, Tomoaki YANO, Kiwamu ASHIDA
    2012 Volume 78 Issue 792 Pages 2860-2869
    Published: 2012
    Released on J-STAGE: August 25, 2012
    JOURNAL FREE ACCESS
    Spherical motor is a multi-degrees of freedom actuator which can be rotated in various directions. However, the control method of the completely arbitrary direction was not fully established in the conventional research. Usually, there were limitation of an angle and a problem of accuracy. In this paper, the general theory which generates torque in the arbitrary direction is proposed using a rotor which has arbitrarily arranged magnets, and a stator which has arbitrarily arranged coils. The theory uses the torque map which included the influence of all the magnets of the rotor. Desired torque is generated by resultant of the torque vector which the coils generate. Therefore, strict control is possible however complicated the pattern of the magnetic field is. First, the technique of the torque generation in the arbitrary direction and the creation method of a torque map are explained. Then, the basic experimental result in the case of the spherical motor with the hexahedron based rotor and the octahedron based stator is reported.
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  • Kensuke HARADA, Torea FOISSOTTE, Tokuo TSUJI, Kazuyuki NAGATA, Natsuki ...
    2012 Volume 78 Issue 792 Pages 2870-2883
    Published: 2012
    Released on J-STAGE: August 25, 2012
    JOURNAL FREE ACCESS
    This paper proposes a method for planning pick-and-place motion by using dual-arm manipulators. In the offline phase of our algorithm, we model the surface of object and environment by using a set of planar regions. The contact between the object and the environment is established by selecting a cluster from both the object and the environment. In the online phase, our planner first generates multiple candidates of object pose stably placed on the environment. We then generate multiple motion strategies including the regrasping motion. The pick-and-place motion is generated by performing the grasp planning selecting one of the object pose and one of the motion strategies. We finally generate collision-free pick-and-place motion by using the PRM (Probabilistic Roadmap Method). The effectiveness of the proposed method is confirmed by simulation and experimental results using the dual-arm robot NX-HIRO.
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  • Ken'ichi YANO, Daiki SAKITO, Tsuginobu OSADA, Norihiko KATO
    2012 Volume 78 Issue 792 Pages 2884-2897
    Published: 2012
    Released on J-STAGE: August 25, 2012
    JOURNAL FREE ACCESS
    Compared with machining by automation, handwork is suitable for the high-variety low-volume manufacturing because it requires a lower cost and a lead time. However, high concentration machining should be implemented in handwork. Furthermore, mistakes generated by a disturbance from the tool rotation results in unless products and wasted materials. This study aims to address as development of the finish machining support system that make it possible to realize high accuracy machining for machining without machining mistakes. Specifically, in this study we developed the fixture-type machining support robot with the parallel link system to achieve good usability and highly accurate machining. We deal with the debburing process at the slit. The feature of this process is that the tool rotational direction is orthogonal to the feed direction. Therfore, the influence of the griding force on the worker's hand becomes more serious and have to be solved. Moreover we estimate the operator's hand stiffness from the machining force and the position of the end effector during grinding. Then, the grinding force is controlled based on the estimated worker's hand stiffness. As a result, the influence of the grinding force on the worker's hand is suppressed, and the decrease of the machining accuracy in handwork is suppressed. Finally, the effectiveness of the proposed method is shown by the grinding experiments and the user test results.
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  • Masafumi HAMAGUCHI, Takao TANIGUCHI
    2012 Volume 78 Issue 792 Pages 2898-2913
    Published: 2012
    Released on J-STAGE: August 25, 2012
    JOURNAL FREE ACCESS
    This paper proposes a cooperative transfer control by using three wheeled mobile robots (WMRs). One WMR is designated as a leader, and other two WMRs are followers. A carrier platform is supported by links with passive joints on the WMRs. The carrier platform is always kept levelly when WMRs run along a straight path on a slope. A level control of the carrier platform is achieved by the position control of WMRs. The reference positions of the followers to level the carrier platform are calculated with a geometric model when the leader runs along target path. The followers are moved to the reference positions with a PID control. The usefulness of the proposed method is demonstrated through simulation and experimental results.
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  • Kensaku KUDO, Kenji SUZUKI, Hideaki TAKANOBU, Hirofumi MIURA
    2012 Volume 78 Issue 792 Pages 2914-2923
    Published: 2012
    Released on J-STAGE: August 25, 2012
    JOURNAL FREE ACCESS
    This paper describes a flapping-wing robot operated at a low resonant frequency. We proposed a light wing with a thin plate that can be resonated by a small battery integrated in the robot at a frequency of 11 Hz. Flapping angles and thrust forces of the resonant wings were measured and compared with those of the non-resonant wings. Experimental results show that the flapping angle of the resonant wings becomes a maximum value at the resonant frequency of 11 Hz, and thrust force at this frequency is 7.8 gf, which is 35 percent larger than that of non-resonant wings. These results demonstrate the proposed wing with a thin plate is effective at low frequencies near 11 Hz. Furthermore, a non-tethered robot with four resonant wings driven by a DC motor and a lithium polymer buttery successfully flew at the resonant frequency of the wings.
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  • Yogo TAKADA, Tsuyoshi NAKAMURA, Keisuke KOYAMA, Tomoki TAJIRI
    2012 Volume 78 Issue 792 Pages 2924-2934
    Published: 2012
    Released on J-STAGE: August 25, 2012
    JOURNAL FREE ACCESS
    It is necessary for a small aqua robot to search for a target in order to investigate creatures such as fishes in a river or lake. However, control signals by electric wave from outside do not reach a robot easily in water. Therefore, aqua robots must search the target autonomously without signals from outside. It is important for a robot to gaze forward and recognize the target in water. In this study, we have used a fish robot named FOCUS which can swim in water by using the tail fin. This robot has some micro CMOS cameras and a FPGA circuit board for data processing. A red object is detected with the CMOS camera. In addition, FPGA calculates where the red object is located in the image. This robot controls the tail fin mechanism and submersible system in order to decide the course of the robot in response to the calculated positional coordinates. We have confirmed that this robot can recognize a color target and follow the target in water.
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  • Yuta KIMURA, Zentaro NEMOTO, Hiroshi TAKEMURA, Hiroshi MIZOGUCHI
    2012 Volume 78 Issue 792 Pages 2935-2949
    Published: 2012
    Released on J-STAGE: August 25, 2012
    JOURNAL FREE ACCESS
    This paper presents that the novel target person detecting and tracking method for mobile robots based on updating multi color HS-histogram. To detect and track a specific person, the image processing with color camera is common method for vision based navigation system of mobile robot. The image processing for the target person detecting and tracking by robot vision has many problems such as the image from the vision device located on robot is often influenced by the change of target size, target moving direction and lighting condition. Moreover, it is difficult to detect a target person in the crowd. To solve these problems, we propose “GRUMIC-HS-hist method (Gradual Updating Multi Color HS-histogram method)”. In the proposed method, the colors of the tracking object are extracted by HSV color space. To decrease the influence of the illumination changes, a HS-histogram is proposed. The extracting colors on HS-histogram are clustered by Nearest Neighbor Method. The colors on HS-histogram are weighted by the anisotropic asymmetric Gaussian distribution to update the HS-histogram without spreading. This proposed “GRUMIC-HS-hist method” achieves the robust target person detecting and tracking by a mobile robot. In addition, the quantitative evaluation method is also proposed to evaluate the proposed target person detecting and tracking method. The quantitative evaluation method is composed with “Extraction Rate”, “Object Detecting Rate” and “Tracking Error”. The quantitatively experimental results show that the proposed “GRUMIC-HS-hist method ” is the robust method for many problems.
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  • Kazuaki YAMADA, Kazuhiro OHKURA
    2012 Volume 78 Issue 792 Pages 2950-2961
    Published: 2012
    Released on J-STAGE: August 25, 2012
    JOURNAL FREE ACCESS
    Reinforcement learning approaches attract attention as the technique to construct the mapping function between sensors-motors of an autonomous robot through trial-and-error. Traditional reinforcement learning approaches make use of look-up table to express the mapping function between the grid state space and the grid action space. However the grid size of the state space affects the learning performances significantly. To overcome this problem, many researchers have proposed algorithms using neural networks to express the mapping function between the continuous state space and actions. However, in this case, a designer needs to appropriately set the number of middle neurons and the initial value of weight parameters of neural networks to improve the approximate accuracy of neural networks. This paper proposes a new method to automatically set the number of middle neurons and the initial value of the weight parameters of neural networks, on the basis of the dimensional-number of the sensor space, in Q-learning using neural networks. The proposed method is demonstrated through a navigation problem of an autonomous mobile robot, and is evaluated by comparing Q-learning using RBF networks and Q-learning using neural networks whose parameters are set by a designer.
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  • Tetsuya NISHIMOTO, Kota NAGAI
    2012 Volume 78 Issue 792 Pages 2962-2971
    Published: 2012
    Released on J-STAGE: August 25, 2012
    JOURNAL FREE ACCESS
    This study examined the potential use of human biosignal reactions for automatic vehicle braking compared to driver reaction and braking in an impending vehicle accident. Reaction times to a visual stimulus and subsequent foot movement for both middle-aged volunteers (male and female) and younger male volunteers were measured while also undertaking lower extremity electromyograms. The electromyogram measure used lower extremity muscle groups tibialis anterior, rectus femoris, peroneus longus and vastus medialis for accelerator and brake pedal operating analysis. Experimental results showed that middle-aged volunteers had longer and more variation in reaction times compared to younger male volunteers. However, electromyogram of tibialis anterior due to volunteer reaction and subsequent accelerator pedal release was similar, regardless of age difference. Based on the results of this study, we found that the detection of tibialis anterior muscle response due to differential processing was 0.1 second faster than the integral processing. Analytical methods are described in this study, and this study shows that the use of the muscular biosignals could be an effective part of a vehicle pre-crash system.
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  • Yanling PEI, Youngwoo KIM, Goro OBINATA, Eiichi GENDA, Kazunori HASE
    2012 Volume 78 Issue 792 Pages 2972-2986
    Published: 2012
    Released on J-STAGE: August 25, 2012
    JOURNAL FREE ACCESS
    Many physical medicine and rehabilitation strategies have been developed for physically disabled people. Most of them have been developed by the physical therapists who assess anatomical and physiological states of the patients. We can design a better rehabilitation method with application of robot technologies, since we can achieve complex motional trajectories in smooth and accurate manner, realize creatively active and passive guidance of patient's limb motion according to the patient's state, and even load and unload on specific muscles. We have developed a sequential design method of lower limb rehabilitation trajectory and external force acting on foot based on a 2D musculo-skeletal model of lower-limb. In this paper, we extend the previously developed method to a 3D musculo-skeletal model for 3D training trajectory and external force design. We introduce spline curves for both smooth position and force tracking trajectories. The structural parameters of the spline curves are explored by applying genetic algorithm. The usefulness of the proposed method is confirmed through simulation results and the comparison with a conventional training trajectory.
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  • Yutaka SATO, Jiaou HE, Hiroyuki KOBAYASHI, Yoshiki MURAMATSU, Takuya H ...
    2012 Volume 78 Issue 792 Pages 2987-2999
    Published: 2012
    Released on J-STAGE: August 25, 2012
    JOURNAL FREE ACCESS
    We have been developing the wearable muscle suit for direct and physical motion supports. The use of the McKibben artificial muscle has opened the way to the introduction of “muscle suits” compact, lightweight, reliable, wearable “assist-bots” enabling manual worker to lift and carry weights. Since back pain is the most serious problem for manual worker, improvement of the back support muscle suit under the feasibility study and quantitative estimation are shown in this paper. The structure of the upper body frame, the method to attach to the body, and the axes addition were explained as for the improvement. In the experiments, we investigated quantitative performance results and efficiency of the back support muscle suit in terms of vertical lifting of heavy weights by employing integral electromyography (IEMG). The results indicated that the values of IEMG were reduced by at least 30% by using the muscle suit. Furthermore, we confirmed that the values of IEMG decreased as much as the case of vertical lifting by adjusting right and left forces supplied even in the case where weights are not at the front.
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  • Ryotaro SABE, Tomohiro HAYASHI, Yoshiyuki SANKAI
    2012 Volume 78 Issue 792 Pages 3000-3012
    Published: 2012
    Released on J-STAGE: August 25, 2012
    JOURNAL FREE ACCESS
    Patients with cerebral palsy who have gait problem need to receive gait training in order to regain the ability to walk without relying on the assistive devices including walkers or canes. It is important for the patients to recognize to how much they depend on the assistive devices by using their arms because the goal is to decrease the dependence on the assistive devices. The purpose of this study is to create a new visual feedback system for helping the patients recognize their dependence on the assistive devices. We developed the new visual feedback system, which measures the load that the patients exert on the handrails, and directly shows this load by using a display. Walking trials of the ten-meter walking test were performed with one patient who has cerebral palsy and one healthy person in order to compare the load that they exerted on the handrails. The visual feedback system was able to measure the load on the handrails and to show it to the patient while he walked. Consequently, the patient was able to recognize the load on the handrails and decreased the dependence on them. This result suggests the new visual feedback system is effective in helping patients to practice to decrease the dependence on the handrails during gait training.
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Technical Paper
  • Mitsuhiro MATSUMOTO, Shin'ichi YUTA
    2012 Volume 78 Issue 792 Pages 3013-3027
    Published: 2012
    Released on J-STAGE: August 25, 2012
    JOURNAL FREE ACCESS
    This paper describes a transportable system for estimating three dimensional motion distance and making three dimensional map in the building environment. This system takes three dimensional laser reflecting points information, and integrates them to make a map in the point cloud format after the estimation of sensing position using the three dimensional motion estimation. It estimates the self-location using the information of surfaces of walls, posts and ceilings as feature of the in-building environment. We have developed the prototype system using a three dimensional scanning unit with the roundly swinging mechanism, and an posture sensor unit. The experimental results have shown the effectiveness of the method of three dimensional motion distance estimation designed for this system.
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Note
Machine Elements, Design and Manufacturing
Regular Paper
  • Yi QIAN, Nobutada FUJII, Toshiya KAIHARA, Susumu FUJII, Toyohiro UMEDA
    2012 Volume 78 Issue 792 Pages 3033-3042
    Published: 2012
    Released on J-STAGE: August 25, 2012
    JOURNAL FREE ACCESS
    In this study, a new concept named Real-Virtual Fusion Manufacturing System (RVF-MS) is proposed, which aims to adaptively and effectively deal with both external and internal fluctuations by realizing a fusion between real production shop floor and virtual manufacturing system model. A concept based on multi-agent system is used for constructing dynamic model in the virtual system. In this paper, production scheduling method at operational phase for RVF-MS is proposed, in which a social contract-based approach named Combinatorial Auction (CA) is applied. The effectiveness of the proposed method is verified by computational experiments for flexible flow shop problems.
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  • Yoshiki SATO, Akira IWABUCHI, Michimasa UCHIDATE, Hitoshi YASHIRO
    2012 Volume 78 Issue 792 Pages 3043-3052
    Published: 2012
    Released on J-STAGE: August 25, 2012
    JOURNAL FREE ACCESS
    In this paper, to study the wear properties of the pipe materials for the nuclear power stations, a high temperature impact fretting test rig was developed. Employing two piezo actuators, this rig can generate impact fretting under various impact loads, fretting amplitudes and frequencies. It also enables us to control water temperature, dissolved oxygen and water pressure. AISI type 304 stainless steel, which is used as a pipe material in nuclear power stations, was used as specimens. Alumina balls were used as the counter materials. Wear property under impact fretting was severer than that under pure fretting and pure impact. The experiment according to L18 orthogonal table has shown that wear was strongly affected by the chemical factors. Especially, water temperature and frequency were significant in the analysis of the wear depth.
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  • Itaru KOURAKATA, Shuichi SAKAMOTO, Yota NAKAO
    2012 Volume 78 Issue 792 Pages 3053-3063
    Published: 2012
    Released on J-STAGE: August 25, 2012
    JOURNAL FREE ACCESS
    A large portion of patients of larynx cancer tekes total laryngectomy and loses their original voice consequently. Some ways to obtain substitute voice for total laryngectomees have been presented, however, each of them cannot conquer inconveniences, tone quality, extremely low tone, monotonousness etc. We invented very simple, small enough to be built in TE (tracheaesophageal) shunt valve but functional substitute voice that is driven by patient's own expiration and its tone pitch can be controlled by expiratory pressure simultaneously. The new device has an outward-striking membrane as an oscillating valve and a set of piston-cylinder mechanism, which controls oscillator's tension and alters pitch of sound. As results of performance experiments applied to the prototype model made as twice scale as an actual dimension, the device produces the lowest sound frequency of 205 Hz and pitch range of 374 cent being approximately proportional to driving air pressure between 0.8 and 2.2 kPa. It is said that normal pitch of female voice is around 210 Hz, thus we consider the possibility of the device as a new substitute voice was shown that contributes to improvement of total laryngectomees' QOL particularly to female patients.
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  • Atsushi YUMOTO, Tadahiko SHINSHI
    2012 Volume 78 Issue 792 Pages 3064-3072
    Published: 2012
    Released on J-STAGE: August 25, 2012
    JOURNAL FREE ACCESS
    We developed a compact centrifugal blood pump utilizing a combination of an axially-controlled magnetic bearing (MB) and an axial flux motor. An experimental pump was 65 mm in diameter and 35 mm in height. The rotor having a six-vaned impeller of 52 mm in diameter could levitate and rotate at a rotational speed of up to 3,000 rpm without contact. It could yield a flow rate of 5 L/min. against a head pressure of 100 mmHg. In order to decrease the axial thrust induced by the unbalance of fluid force working on the rotor and reduce the power consumption of the MB, the arrangement and diameter of balance holes through the rotor were surveyed using computational fluid dynamics (CFD) simulation.
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  • Toshimichi FUKUOKA, Masataka NOMURA, Yutaro UEMORI
    2012 Volume 78 Issue 792 Pages 3073-3084
    Published: 2012
    Released on J-STAGE: August 25, 2012
    JOURNAL FREE ACCESS
    When pipe flange connections clamped with sheet gaskets are subjected to thermal load, the bolt preloads that tighten a pair of pipe flanges tend to decrease. It has been studied in the previous paper why and how the bolt preloads decrease, in which the loading and unloading curves of sheet gaskets at elevated temperature are expressed by simple equations. Meanwhile, it is also known that the bolt preloads are likely to decrease when the plant is shut down. In this paper, a numerical procedure, which can estimate the amounts of bolt preload reduction occurred in the shutdown process, is proposed using axi-symmetric FEM. The analytical objects are pipe flange connections tightened with aramid sheet gaskets. In the finite element formulation, the stress-strain curves of the gaskets after plant shutdown are approximated by simple curves, considering that the hysteresis appeared in the curves is fairly small comparing to the loading and unloading curves. It is shown that the bolt preloads decrease as much as 50% of those in the running condition. The validity of the proposed numerical method is confirmed by comparing the numerical results of bolt preload reduction to experimental ones.
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  • Ryo NISHIYAMA, Keiichi NAKAMOTO, Tohru ISHIDA, Yoshimi TAKEUCHI
    2012 Volume 78 Issue 792 Pages 3085-3092
    Published: 2012
    Released on J-STAGE: August 25, 2012
    JOURNAL FREE ACCESS
    Corresponding to diverse consumer needs, high-mix and low-volume production is becoming more important. Unique products matching consumer's sensitiveness tend to be welcome. These products will be something like art and craft products, which require skill and experience to create. This study deals with 5-axis control tool path generation to dexterously and efficiently create such craft-like microshapes, while maintaining the quality. Concerning 5-axis control machining, the way of using ball end mills is generally employed. However, it needs a lot of time to get high quality surface. To solve this problem, a side cutting edge of the ball end mill is positively utilized with its tool axis parallel to the ruled surface. Therefore, a new CAM system is developed to detect the surface to be machined with the side cutting edge, and to generate the collision-free tool paths between the tool and the workpiece. The effectiveness of the developed CAM system is experimentally confirmed by creating a tiny Möbius ring.
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  • Masato OKADA, Akira HOSOKAWA, Naoki ASAKAWA, Yusuke FUJITA, Takashi UE ...
    2012 Volume 78 Issue 792 Pages 3093-3103
    Published: 2012
    Released on J-STAGE: August 25, 2012
    JOURNAL FREE ACCESS
    The effect of minimum quantity lubrication (MQL) method in end milling of stainless steel and titanium alloy that are typical difficult-to-cut materials with coated carbide tool is investigated. The effect is mainly evaluated by tool flank temperature, cutting force and tool wear behavior. The tool flank temperature is measured using a two-color pyrometer with an optical fiber having small measurement area and high response speed under non-contact condition with tool. In MQL cutting of SUS304 and Ti-6Al-4V at cutting speed v=25m/min, the tool flank temperature decreases approximately 50°C and 100°C than the case of dry cutting respectively, and the effect of MQL on tool flank temperature is especially obtained in low-speed cutting. On the other hand, the tool flank temperature in MQL cutting of Ti-6Al-4V is higher than the case of dry cutting in cutting speed v=100m/min or more. In the high-speed cutting of Ti-6Al-4V, it is observed that the several chips adhere on the rake face of cutting edge. In addition, the output voltages from detector are obtained when the adhesion chips on the cutting edge pass through the measurement area of two-color pyrometer. In the case of the SUS304, the feed and thrust force are decreased by the supplying oil mist in high speed cutting. The generation of micro-crack at cutting edge is contained by applying MQL even high speed cutting of Ti-6Al-4V that is not obtained the effect of temperature decreasing.
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