IOP PublishingActa Medica Okayama0021-49226332024Evaluation of transducer for cryogenic actuators by equivalent circuit model03SP03ENKazukiKuboGraduate School of Environment, Life, Natural, Science and Technology, Okayama UniversityKairiYagiGraduate School of Environment, Life, Natural, Science and Technology, Okayama UniversityTakefumiKandaGraduate School of Environment, Life, Natural, Science and Technology, Okayama UniversityKoaYasudaGraduate School of Environment, Life, Natural, Science and Technology, Okayama UniversityDaisukeYamaguchiGraduate School of Environment, Life, Natural, Science and Technology, Okayama UniversityShuichiWakimotoGraduate School of Environment, Life, Natural, Science and Technology, Okayama UniversityCryogenic environments are increasingly used in scientific and industrial fields. Recently, cryogenic environments are also used for storage and supply of liquid hydrogen, which is considered essential for the realization of a decarbonized society. Actuators to drive a valve that controls such a low-temperature fluid are required. In this study, a piezoelectric transducer that can be driven in the cryogenic environment has been fabricated and evaluated. Although the performance of piezoelectric elements degrades at cryogenic temperatures in general, the application of a preload can suppress the degradation of performance. Equivalent circuits were used for evaluation, and force factors and figures of merit were compared. As a result, the force factor was as high as that at RT even at cryogenic temperatures, and a high figure of merit was obtained. The result indicates that the transducer can be used for the driving of micro actuator at cryogenic temperature.No potential conflict of interest relevant to this article was reported.MDPIActa Medica Okayama1424-82202292022Displacement Sensing of an Active String Actuator Using a Step-Index Multimode Optical Fiber Sensor3232ENWeihangTianGraduate School of Natural Science and Technology, Okayama UniversityShuichiWakimotoGraduate School of Natural Science and Technology, Okayama UniversityTakefumiKandaGraduate School of Natural Science and Technology, Okayama UniversityDaisukeYamaguchiGraduate School of Natural Science and Technology, Okayama UniversityA thin McKibben artificial muscle is a pneumatic actuator with an outer diameter of only 1.8 mm. We fabricated a string-shaped actuator called an "active string actuator," which achieves a high contractile displacement by accumulating thin McKibben artificial muscles. To control the displacement, the length of the active string actuator should be estimated. However, this is difficult because bulky and rigid sensors are unsuitable for the sensor element of the active string actuator. Therefore, in this study, we propose a new sensing method for estimating the length of an active string actuator. The proposed sensing system is simple and comprises only three components: a step-index multimode optical fiber, a light emitter, and a light receiver. A step-index multimode optical fiber was combined with the active string actuator, and the length was estimated from the change in the amount of light propagating in the optical fiber when the active string actuator was driven. Fundamental experiments were conducted in this study, and the results demonstrated that the optical fiber sensor value changed with the actuator length. This suggests that it is possible to estimate the displacement of an active string actuator using an optical fiber sensor.No potential conflict of interest relevant to this article was reported.MDPIActa Medica Okayama2076-08251032021Core-Shell Droplet Generation Device Using a Flexural Bolt-Clamped Langevin-Type Ultrasonic Transducer55ENKentaroOmoriGraduate School of Natural Science and Technology, Okayama UniversityNozomuFujimotoGraduate School of Natural Science and Technology, Okayama UniversityTakefumiKandaGraduate School of Natural Science and Technology, Okayama UniversityShuichiWakimotoGraduate School of Natural Science and Technology, Okayama UniversityNorihisaSenoGraduate School of Natural Science and Technology, Okayama UniversityDroplets with a core-shell structure formed from two immiscible liquids are used in various industrial field owing to their useful physical and chemical characteristics. Efficient generation of uniform core-shell droplets plays an important role in terms of productivity. In this study, monodisperse core-shell droplets were efficiently generated using a flexural bolt-clamped Langevin-type transducer and two micropore plates. Water and silicone oil were used as core and shell phases, respectively, to form core-shell droplets in air. When the applied pressure of the core phase, the applied pressure of the shell phase, and the vibration velocity in the micropore were 200 kPa, 150 kPa, and 8.2 mm/s, respectively, the average diameter and coefficient of variation of the droplets were 207.7 mu m and 1.6%, respectively. A production rate of 29,000 core-shell droplets per second was achieved. This result shows that the developed device is effective for generating monodisperse core-shell droplets.No potential conflict of interest relevant to this article was reported.Acta Medica Okayama0924-42471842012An ultrasonic motor for cryogenic temperature using bolt-clamped Langevin-type transducer134140ENDaisukeYamaguchiTakefumiKandaKoichiSuzumoriIn this study, a small ultrasonic motor driven under cryogenic temperature conditions has been fabricated and evaluated.
Since transducer performance generally decreases at cryogenic temperatures, we designed and fabricated a bolt-clamped Langevin-type transducer for operation at cryogenic temperature. We simulated the influence of thermal stress on the transducer. The results from simulation were used to design the transducer, and it was then used to fabricate an ultrasonic motor for cryogenic temperature. The maximum diameter and the height of the motor are 30 mm and 38.7 mm.
To enable the motor to be driven at cryogenic temperature, we evaluated the relationship between the contact pre-load and the lowest rotatable temperature. The motor's driving performance was evaluated at both room temperature and cryogenic temperatures. In a 4.5 K helium gas ambient, the rotation speed and starting torque were 133 rpm and 0.03 mu N m when the applied voltage was 50 Vp-p.No potential conflict of interest relevant to this article was reported.ElsevierActa Medica Okayama0924-42471641-22010Multiplex pneumatic control method for multi-drive system8894ENYasutakaNishiokaKoichiSuzumoriTakefumiKandaShuichiWakimotoPneumatic actuators have several advantages such as light weight safety low cost and high compliance However many pneumatic actuators have complicated systems that include a compressor air tubes and pneumatic valves with electrical wires This research proposes a new control method for a multiplex pneumatic transmission constructed with special resonant valves and air tubes with a control system driven by air vibration in air tubes without electrical wires The control is simplified and effective for pneumatic systems having many degrees of freedom In this paper the development of a primitive model of the resonant valve and a prototype valve is described In addition two control methods which are a superimposing method and a time-sharing method are shown and the independent driving of four actuators is realized by using one of the control methods with air tubes only.No potential conflict of interest relevant to this article was reported.Acta Medica Okayama12712006A micro ultrasonic motor using a micro-machined cylindrical bulk PZT transducer131138ENTakefumiKandaAkiraMakinoTomohisaOnoKoichiSuzumoriTakeshiMoritaMinoru KuribayashiKurosawa<p>In this paper, a micro ultrasonic motor using a micro-machined bulk piezoelectric transducer is introduced. The cylindrical shaped bulk piezoelectric transducer, a diameter of 0.8 mm and a height of 2.2 mm, was developed as stator transducer for traveling wave type ultrasonic motor. The transducer was made of lead zirconate titanate (PZT) bulk ceramics, and formed by micro machining, Ni plating and laser beam cutting process. Using this stator transducer, we have fabricated a cylindrical micro ultrasonic motor, a diameter of 2.0 mm and a height of 5.9 mm. We have also evaluated some characteristics and succeeded in driving the micro ultrasonic motor.</p>
No potential conflict of interest relevant to this article was reported.Acta Medica Okayama2004Nutation motor : a new direct-drive stepping motor for robots2122ENKoichiSuzumoriTakefumiKandaKazuoUzukaIsaoEnomoto<p>A new type of stepping motor, named nutation motor was developed. This motor has a reduction mechanism consisting of a pair of bevel gears, realizing high torque and high resolution stepping motion. Three prototypes, two pneumatic nutation motors and an electric nutation motor, were designed, developed, and tested. We show the basic driving principle and the experimental results in this paper.</p>
No potential conflict of interest relevant to this article was reported.Acta Medica Okayama42004Active link mechanisms for physical man-machine interaction38953900ENJumpeiOchiTatsuyaHashimotoKoichiSuzumoriTakefumiKanda<p><p>In this paper, we propose a new type of haptic interface, named active link mechanism. This device realizes physical man-machine interaction (PMI) between machines and persons. Two prototypes were developed to demonstrate the potential of the active link mechanisms. Developed interface devices are an active tetrahedron and an active icosahedron. Nine-DOF micro spherical joints and pressure control pneumatic cylinders were developed to realize the active tetrahedron, while fifteen-DOF micro spherical joints and intelligent pneumatic cylinders were developed for the active icosahedron. The tetrahedron successfully realizes "virtual touch"; the operators feel actions, forces, and shapes of the virtual objects in PC and also move and deform them. Real time PMI is realized by building the developed devices into MSC.Visual-Nastran4D. MSC.VisuaI-Nastran4D is a mechanism analysis software, which can make motion analysis in real time. The active icosahedron also realized dynamic interaction with virtual objects in PC, showing the potential of the devices as a haptic interface.</p></p>
No potential conflict of interest relevant to this article was reported.Acta Medica Okayama2004Development of active icosahedron and its application to virtual clay modeling175180ENJumpeiOchiTatsuyaHashimotoJunichiTanakaKoichiSuzumoriTakefumiKanda<p>We have developed an active link mechanism for physical man-machine interaction. We report an active icosahedron consisting of intelligent cylinders and its application to virtual clay modeling. Intelligent pneumatic cylinders are newly developed to realize active link mechanisms. This cylinder aims at a novel cylinder in which various sensors and control devices are built. Active link mechanisms are highly integrated and enhanced by intelligent cylinders. A control system is built for the active icosahedron. In the control system, a key element is a control program implementing drawing of a virtual model on display and controlling of active links. Virtual clays are deformed by the program based on the apex positions converted from cylinder lengths. The active icosahedron realized dynamic interaction with virtual objects in PC, showing the potential of the devices as a haptic interface.</p>
No potential conflict of interest relevant to this article was reported.Acta Medica Okayama12005A cylindrical micro ultrasonic motor using micro-machined piezoelectric vibrator721724ENTakefumiKandaAkiraMakinoYoshitakaOomoriKoichiSuzumori<p>A micro ultrasonic motor using a micro-machined cylindrical bulk piezoelectric vibrator is introduced. This motor consists of the vibrator, a glass case and a rotor. The diameter of the piezoelectric vibrator is 0.8 mm and that of the motor case is 1.8 mm. Since the stator transducer is fixed at the end of the cylinder, it is easy to support the vibrator and the structure of the motor is not complicated. In addition, the vibrator and rotor are supported by the glass case. This is important for the micro ultrasonic motor because it is difficult to support the vibrator when the vibrator is miniaturized. We have fabricated and evaluated the cylindrical shaped traveling type micro ultrasonic motor using this vibrator.</p>
No potential conflict of interest relevant to this article was reported.Acta Medica Okayama12005Development of intelligent McKibben actuator with built-in soft conductive rubber sensor745748ENShuichiWakimotoKoichiSuzumoriTakefumiKanda<p>This study aims at the development of an intelligent McKibben actuator, in which a soft rubber displacement sensor is integrated. Recently, the McKibben actuator has attracted engineers because of light weight, high output power and high compliance. But in the case of using it for servo control at present, the systems need encoders or potentiometers, therefore the systems tend to grow in size and take away from compliance which is an important advantage for a safe and secure mechanism. We have developed a soft displacement sensor and incorporated it in a McKibben actuator, named it the intelligent McKibben actuator, and proved its potential.</p>
No potential conflict of interest relevant to this article was reported.Acta Medica Okayama42004Active link mechanisms for physical man-machine interaction38953900ENJ.OchiTatsuyaHashimotoKoichiSuzumoriJ.TanakaTakefumiKanda<p>In this paper, we propose a new type of haptic interface, named active link mechanism. This device realizes physical man-machine interaction (PMI) between machines and persons. Two prototypes were developed to demonstrate the potential of the active link mechanisms. Developed interface devices are an active tetrahedron and an active icosahedron. Nine-DOF micro spherical joints and pressure control pneumatic cylinders were developed to realize the active tetrahedron, while fifteen-DOF micro spherical joints and intelligent pneumatic cylinders were developed for the active icosahedron. The tetrahedron successfully realizes "virtual touch"; the operators feel actions, forces, and shapes of the virtual objects in PC and also move and deform them. Real time PMI is realized by building the developed devices into MSC.Visual-Nastran4D. MSC.VisuaI-Nastran4D is a mechanism analysis software, which can make motion analysis in real time. The active icosahedron also realized dynamic interaction with virtual objects in PC, showing the potential of the devices as a haptic interface. </p>
No potential conflict of interest relevant to this article was reported.Acta Medica Okayama2005Development of intelligent McKibben actuator487492ENShuichiWakimotoKoichiSuzumoriTakefumiKanda<p>The aim of this study is to develop an intelligent McKibben actuator with an integrated soft displacement sensor inside, so that displacement of this actuator can be controlled without having any extra devices attached. In addition, the high compliance which is a positive feature of the McKibben actuator is still conserved. This paper consists of four main parts. First of all, different types of soft displacement sensors made out of rubber were composed, and tested for their functional characteristics. Secondly, the intelligent McKibben actuator was developed with the soft displacement sensor incorporated within. Then, experiments of the position servo control with a single intelligent McKibben actuator were carried out. At last a robot arm mechanism was designed with two intelligent McKibben actuators, and those experimental results showed a great potential for its future applications.</p>
No potential conflict of interest relevant to this article was reported.Acta Medica Okayama2003A micro snake-like robot for small pipe inspection303308ENShuichiWakimotoJunNakajimaMasanoriTanakaTakefumiKandaKoichiSuzumori<p>The goal of this research is development of a micro robot which can negotiate pipes whose diameter varies widely. The robot mechanism is based on "snaking drive". First, in section 1 to 4, basic characteristics of the snaking drive are discussed: the principle of the snaking drive is shown, theoretical fundamental formulas are derived, and the motions of the robot are simulated. Second, in section 5, a micro robot was designed, fabricated and tested. And fundamental experiments of the robot are shown. Third, in section 6, two application experiments are shown: one is a stabilization of camera image, and the other is a robot steering at branches. The robot moved in pipes whose diameter varies between 18 mm to 100 mm with the maximum speed of 36 mm/s. And the robot could negotiate T-branches and L-bends of pipes.</p>
No potential conflict of interest relevant to this article was reported.