The transient response of induced shear stress and the related flow behavior of two types of the ER fluids containing particles have been investigated when they have been under the simultaneous stimulus of an constant DC or AC electric fi eld and shear using a parallel rotary disk rheometer. For only one type of the ER fluid containing sulfonated polymer particles, as the electric field strength increases, the particles in the ER fluid form lamellar formations in the direction of shear, which may be responsible for the ER activity more than the strength of the chains. And, as the gap of parallel disks decreases down to about 0.1 mm, the particles gather around the outer edge of the disk to form a thick ring of the aggregation of the particles, which may be responsible for the increase of the shear stress. In this way, it would be expressed that the shear stress should change consistently with the morphology of the formations. In this work, the effects of shearing time, electric field strength, DC or AC, gap height between disk electrodes and types of ER fluid on the shear stress and the flow morphology are investigated.

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In the paper, the Electrorheological fluid (ERF) is embedded in the pneumatic vibration isolator and three kinds of control systems are designed, which experimental results are also compared. The first kind of the control system is the semi-active control system, which is designed for ERF controllable damper. The second kind of the control system is the active control system, which is designed for the air servo position control of the platform of the pneumatic vibration isolator. The third kind of vibration isolator control systems is the combination of the active air servo control system and the ERF controllable damper. The experimental results are shown and compared to those of the passive pneumatic vibration isolators, the transmissibility of a vibration source to the isolation platform can be reduced by the first control system. Using the second kind of the control system, the transmissibility of the system is less than that of the first kind of the control system. Using the third control system, the transmissibility becomes the least of these control systems.

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The Multi-pass filter test is the most common method to evaluate the performance of hydraulic filters. The test is conducted at a constant flow rate at constant temperature and very high dirt ingression in order to evaluate filter performance at accelerated test condition. This standard test does not represent operating condition of the modern hydraulic control systems. In order to precisely represent filter performance in the field in the laboratory, the Cyclic Stabilization Test (CST) has been developed. The CST can reliably measure the ability of the filter to control contamination in an even lower ingression environment. It also simulates cyclic flow condition to measure filter performance. In this paper, the CST is proposed as a more effective method for filter performance evaluation method.

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Contamination control is a technology to keep working fluids clean. Using a hydraulic filter is the commonest means of keeping the working fluid clean. The contamination level of a fluid exiting a filter increases with the operating time of the filter. The pressure loss across a filter element increases when the element retains contaminants. To describe these variations with operating time, this paper proposes:(1) a filter clogging model with an effective opening area;(2) a pressureloss model related to the effective opening area;(3) a filtration model concerned with the effective opening area and the mean lodging time of particles;(4) a quasi-single-pass test method for evaluating the filtration performance of a filter. The paper also shows a system of equations describing contamination levels in fluid power systems and discusses the relevant industrial standards which are presently widely used.

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A novel test apparatus used to measure the pressure distribution of spool valve with notches has been designed, thus the mechanism of the noise differences related to the different notches can be investigated. Some small holes used to detecting pressure were arranged on a sleeve that can be shifted and rotated in preset locations. Several ways are introduced to minimize the internal leakage, which include the hydraulic force used to close the gaps between the sleeve and valve body, the large distance between the small holes and a high requirement of small clearances between the body, the spool and the sleeve. The effect of this test apparatus on the flow field inside the valve is limited to the minimum to improve the accuracy of the method proposed. The experimental results of pressure distribution are agreed well with the CFD results as a whole, particularly in diverging flow direction in notch (called ‘FLOWOUT’). In converging flow (call ‘FLOWIN’), the correspondence between the experiment and CFD results is not good as the former due to the numerical errors in CFD. The CFD and experimental results of two typical notches, the sloping notch (V-notch) and the notch with a passage of same cross-section areas (U-notch), was presented in this paper. As a result, it is revealed that the U-notch has a two-stage orifice characteristic that can be helpful to suppress the cavitation noise.

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This paper studies the energy efficiency of a heavily loaded cylinder drive. Pulse code modulation is used to control all four flow path independently with parallel connected on/off valves. A valve manifold with 4x5 two-way screw-in cartridge valves is used and the dimensions of the test system are such that actuator size, load force, effective inertia and natural frequency are at the same level as in joint actuators of typical medium size mobile machines. A cost function based control solution is used for online minimization of power losses. Power losses are compared with traditional proportional load-sensing system.

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In this study we investigate development of energy saving system for hydraulic excavator. In the system an accumulator storages power when energy exceeds and assists necessary power which is required by the actuators. As a first step of the study, simulation program of the system is developed. By using the simulation program it is expected that the static and dynamic performance is easily grasped. And it will contribute to the rationalization of the system design. In this paper, the validity of the energy saving system is evaluated.

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With the great advancement of Internet, the bilateral telecontrol system will enable operator to accomplish complicated tasks with haptic information all over the world. The paper emphasizes on the mainproblem of such system, that is variable time-delay which brought by the Internet will cause the telecontrol system to be unstable. Firstly, after the discussion about the master-salve operation and the effect of Internet to it, one kind of control architecture based on compensator, which can ensure the stability of system with constant time-delay, isproposed. Secondly, the uncertainty characteristic of the time-delay is described under TCP and UDP separately, and the problems of the two protocols in telecontrol system are presented, and also the corresponding solution is given out. Thirdly, in order to solve those uncertainty problems, using the idea of sliding mode control, the telecontrol architecture with switching compensator is investigated.

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Reliability is essential for electro-hydraulic systems due to the high energy densities associated with their operation. A failure can have catastrophic results, for example, if a contamination failure of hydraulic fluid at high pressure occurs. A novel approach for fault diagnosis of hydraulic systems has been proposed, using genetic algorithms as the parameter optimization method, and model based simulation. Performance tracking of critical parameters within the hydraulic system assesses subtle state changes and attempts to identify failure modes associated with these state changes. The proposed approach, which requires analysis of each component of the hydraulic system under normal operation and with specific, induced failure modes, has been successfully applied to a hydraulic system incorporating a servovalve and linear actuator. The results of this study provide a basis for future studies of more complex hydraulic components and systems.

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The consumption of fossil fuels is one of the largest problems facing humankind. One of the heaviest users of our non-renewable resources is the automotive industry, in particular, the heavy road transport sector. Tightening worldwide legislation aims to place restrictions on the heavy transport industry to reduce its use of fossil fuels and reduce the levels of pollution being released to the atmosphere. Although several different alternatives to the conventional Internal Combustion Engine (ICE) have been investigated, none have as yet become a competitive source of energy. Alternative research into development of hybrid-drive vehicles was specifically concerned with electric hybrids especially for passenger vehicles. Currently there is a resurgence of interest in the Hydraulic-type Hybrid Vehicle (HHV) in application to commercial and to a lesser degree to large passenger vehicles. This paper gives an overview of hydraulic hybrid technology.

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As fluid power systems improve their performance, the demand for their safety and reliability increases and so the failure analysis plays an important role. In the product lifecycle, the failure analysis is performed before and after the launch of the product. The former is a kind of conventional risk analysis to prevent system failure in the design process, while the latter identifies the cause of a customer's complaint; why the product cannot work as the customer expects. This paper considers an information management for the latter, which is divided into two processes: one is to answer the customer's complaint, and the other is to improve the product quality. Based on its objective, a different kind of information flow must be organized. Since fluid power systems work in various operating conditions, the clear specification of environmental factors is essential. An illustrative example shows a simplified treatment process of a customer's complaint.

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This investigation aims to develop an intelligent hybrid pneumatic-piezoelectric servo positioning system with high response, large stroke and nanometer precision. The rodless pneumatic cylinder serves to position in coarse stroke and the piezoelectric (PZT) actuator compensates fine stroke. Thus, the overall control systems become a dual-input single-output (DISO). Although the rodless pneumatic cylinder has relative higher friction force, it has the advantage of mechanism for multi-axes development. In order to develop an intelligent controller, self-organizing fuzzy sliding mode control theory (SOFSMC) is proposed here for the DISO system. SOFSMC is based on fuzzy sliding mode control (FSMC) combining with self-organizing strategy. Thus, SOFSMC has simple fuzzy rule base and on-line selforganizing ability. Besides, in order to reduce the coupling effects of the DISO system, a decoupling controller is developed. The experimental results clarify that the servo pneumatic-piezoelectric control system can achieve excellent positioning response and accuracy of 20 nm with high response for maximum stroke of 250 mm and multi-step positioning

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Neither high accumulation nor densification on micro mechatronics are so advanced comparing with semiconductor devices. Our research aims at the establishment of design and fabrication to perform miniaturization, high accumulation and high densification by integrating mechano-micro elements. In difficult assembly of these elements, a stereolithography method is used to form the entire micro fluid power systems in all-in-one design including actuators, pumps and valves. In this paper, prototype models based on a bourdon type and diaphragm type of micro fluid power devices are fabricated and experimentally investigated. Some problems regarding design and fabrication of micro fluid power systems are discussed.

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For millimeter-sized fluid-driven micromachines performing power-needed tasks, we proposed a novel micropump using fluid inertia in an outlet pipe. The paper describes the pump structure for higher output power and an application of the micropump to a micro fluid power system. First, a simple nonlinear mathematical model with lumped parameters was proposed and the validity was confirmed comparing the simulation and experimental results. Second, based on the simulations varying the sizes of the outlet pipe and the diaphragm, the pump structure for higher output power was obtained and the validity was verified through experiments. Finally, as an application of the micropump, a position control microsystem was fabricated using the micropump, a microvalve using magneto-rheological fluid valve-body, and a bellows microactuator. The characteristics were experimentally clarified and the validity was confirmed.

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In the field of MEMS technology, the high accumulation and high density for making semiconductor devices are rapidly advanced. On the other hand, neither high accumulation nor densification on micro mechatronics are so advanced comparing with semiconductor devices. In our laboratory, it pays attention to microfluidic systems which can control fl uids without mechanical moving parts. In this paper, design and fabrication of microfluidic devices with small, light and integration are discussed. A prototype models based on fluidics is fabricated and experimentally investigated. A view point of future application for the micro fluidic devices is also reported.

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Grooves effects on slippers are understood from a qualitative point of view and analytically for slippers without grooves. This study addresses the effect of groove dimensions and position via expanding the equations of flow, pressure distribution and force developed for any number of lands. A unique advantage of having explicit equations is that they may then be used to design slippers in order to have maximum lift, via optimizing the groove length, depth and position. This cannot be achieved at present using previous knowledge apart from many simulation runs using a numerical simulation package.

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External gear pumps are the most widely employed source of power in hydraulic applications, allowing good performance and low manufacturing costs. The present paper reports the description of a numerical model for the simulation of these kind of machines, developed by the authors. The model has been implemented using the software AMESim^®, introducing new in-house C++ models, with the main aim of an accurate prediction of the pressure ripple at the delivery port and the calculation the flow rate time course through the pump. In fact the reduction of flow pulsations is one of the crucial targets in the development of these machines.
The fluid dynamic model of the pump is based on a finite volumes framework: each chamber presents uniform fluid proprieties and is connected with the adjoining ones by variable orifices. The pump is described by the interaction between a fl uid dynamic model, that predicts the instantaneous pressures and the flow rates between the chambers, with a geometrical sub-model for the evaluation of the actual values of the variable volumes (defined by teeth, housing, and side wear plates) and the throat areas, as functions of the shaft angular position.
This paper reports a deep description of the fluid dynamic model and a comparison between its numerical results and data available from experiments, showing how a correct evaluation of the flow when the chambers expand (and oil is pushed from the supply tank) or decrease (and oil is ejected into the outlet port) allows a good prediction of the pump characteristics.
The results reported in the paper show how the model can be a powerful tool for design and development of external gear pumps, e. g. it easily allows the prediction of the maximum and minimum pressure reached inside the teeth space volumes, giving important information to prevent cavitation and damages as well as to reduce the pump noise. Moreover the simulation environment easily allows the evaluation of the pump behaviour when it works in a given hydraulic system.

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Hydraulic pump performance monitoring methods that can detect failures by using the outlet pressure signals of the pump are investigated. Two faults diagnosis methods, namely conventional spectral analysis method based on FFT and wavelet based multi-resolution analysis method, are introduced and their efficiency and reliability are discussed. The performance of both diagnoses methods were evaluated based on simulation results and experimental results. Validation results obtained from using both methods in analyzing the same sets of data indicated that the wavelet transform based fault diagnosis method showed a more sensitive and robust detecting results for all three tested pump faults than that obtained from a spectrum analyses approach.

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A new type of camshaft connecting-rod low speed high torque (LSHT) hydraulic motor providing continuously variable displacement is presented in this paper. On the base of traditional LSHT hydraulic motor with dual displacement, a continuously variable displacement mechanism, which is composed of a hydraulic control valve with mechanical-positional feedback to camshaft, is designed for the traditional LSHT hydraulic motor. So the cam ring on camshaft of the traditional LSHT hydraulic motor can stop at any position between minimum and maximum eccentricity, according to an input fluid pressure signal or an input electric control signal, and can stay anywhere stabilized through self-adjusting. The new type of continuously variable displacement mechanism is simple, stable and easy to be made. Firstly, the structure and principle of the continuously variable displacement mechanism is introduced in this paper. Secondly, the mathematic model is set up.

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An articulation-type passive element is a planate bag containing articulating thin plates. It can be freely contracted and bent to fit an arbitrary rounded surface. Evacuation of the internal air renders the bag rigid so that it maintains whatever shape it has been given. The stiffness of the articulation-type passive element is proportional to the reduction in internal pressure below atmospheric pressure. Experimental results show that the stiffness is higher and more stable than that of other passive elements that function by vacuum pressure. As an application of the new passive element, we developed an orthopedic cast that is easy to remove or change in shape. The passive element is also applicable to wearable force displays. Passive elements fixed on an operator provide a sensation of reaction force by constraining his or her motion. The new passive element is suitable for wearable mechanisms, by virtue of being lightweight, soft, and safe.

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Recently, development of instruments for minimally invasive surgery has been considerably required. This surgical procedure, as compared with traditional open surgery, enables the incision smaller, and this result in less patient pain and shorter duration of hospital stays. However, it requires increased skill on the part of the surgeon. To solve this problem, robotic manipulators using electric actuators that have multi-DOFs at thetip of them have been reported as alternative to conventional instruments. These systems, however, has the problem that force sensing is difficult. In this paper, we propose a master-slave manipulator using pneumatic cylinders as actuators that can be useful for laparoscopic surgery. This system can provide force feedback to the surgeon from the differential pressure of the cylinders. We designed a bilateral dynamic control system using neural network for acquisition of the inverse dynamics. The obtained inverse dynamics is used for feedforward and estimation of the external force. Experimental results showed that the developed system successfully display the contact force.

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We have developed a human walking assist system for the people who have handicap or are injured.
A pair of orthosis which actuated by pneumatic liner actuators and shoes having a weight sensor makes up this system. The reason why we decide to use pneumatic actuators is that the pneumatic characteristic caused by air pressure is soft for human and also fits for environment. This assist system supports the lift of legs and stretch of knees when the human walks on ground or stairs. The supportable angles of knee are enough large and this system can be widely used.
We will evaluate the usefulness of this system by the factor of human power reducing for walk and his impression for use.

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At the close of the 20^th century, in Japan, the reduction of incidence of the care worker in an aging society is becoming pressing need. Then, we aim at the development of the robot arm for care which is flexible and united with the motion of man.
In this subject, we suggest to develop the “Tendon-Driven 2-Link Manipulator Driven by Pneumatic Cylinder” as the care lift for assisting the rising and sitting of elderly people, disabled people or wheelchair users.
The tendon-driven manipulator system developed in this subject makes use of the pneumatic cylinder as an actuator. A pneumatic actuator is characterized by enabling the flexible action by the compressibility of the air. By means of the fl exible action caused by the compressibility of the air, the welfare system making use of a pneumatic actuator can be expected to the “Human-Friendly Assist”.

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We have developed a haptic glove system to use rehabilitation field, e.g. rehabilitation robotics system. This glove has angle sensors to detect each finger position and small balloons inside of the glove to present a force to the user who wear the glove by pressurized 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 glove user. To control this force feedback system, we use PWM control method to show the quantity of the force. Force affecting the user is updated by a frequency of 10Hz and has several steps resolution. Total weight of this glove with haptic feedback capabilities is less than 200 grams. We tried to use this glove as a master-slave hand system, we could feel the slave hand force though haptic glove like a real force.

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The oscillating LPA (Laminar Proportional Amplififier) flow sensor having bilateral feedback loops is available for the measurement of small volume flow. Pattern of LPA and feedback loops were sculpted on a flat plane. The relationship between the oscillating frequency and the geometry of the oscillating LPA flow sensors were measured. As the result of experiments, it was appeared that the oscillating frequency of the oscillating LPA flow sensor closely connected with the geometry and the sizes of the sensor, and the signal transport time through the feedback loop was about a half of the acoustic time delay, and it was proved that the signal transport time on the supply jet from the supply nozzle to the splitter were occupied about 60% of the oscillating frequency. It was demonstrated that the range ability of the oscillating LPA flow sensor could be extended by arranging the pattern of LPA and feedback loops in the same plane.

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In this paper the flow field in swirler is measured by five-hole probe, hotwire and LDV. Laser Doppler Velocimetry. These results would be much the same. It can provide some ideas for design of swirler.

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This paper proposes a new mathematical model to describe the mass flow-rate characteristics of gas through orifice-type restrictors in aerostatic bearings. In the conventional design of gas-lubricated aerostatic bearings, the mass flow-rate of gas through an orifice-type restrictor is generally derived from a well-known mathematical model, which is originally developed to describe the mass flow-rate property of gas through an ideal nozzle. In this paper, however, a series of CFD-simulations and experiments according to ISO 6358 are carried out and the results show that the mass flow-rate characteristics through an orifice-type restrictor are different from those through an ideal nozzle. Consequently, the conventional model to determine the mass flow-rate of gas through orifice-type restrictors in aerostatic bearings may have to be modified and updated to the proposed new model for more precise design and modeling of the gas-lubricated aerostatic bearings.

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A new measurement method of the flow-rate characteristics of a regulator was proposed in this paper. Through charging a chamber connecting with the outlet of the regulator and measuring the pressure response in the chamber with a pressure sensor, the flow-rate characteristics curve was obtained from these sampled data. The process needs only one charge, so it brings high efficiency, good precision and less air consumption. The new method was studied through numerous simulations and experiments at different pressures. Results obtained from experiments and simulations were compared to find in good accordance, which verified the feasibility of the new measurement method.

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This paper presents a global characterization and an analytical model of the static flow stage of an electro-pneumatic proportional valve FESTO MPYE-5-M5-010-B. This study is useful for linear or nonlinear control synthesis in our application for medical robotics. Firstly, the experimental measurements are carried out using 3D graphs where a set of curves gives the output mass flow rate as a function of the electrical input of the electronic stage for different values of the output pressure. The exhaust and supply pressures, during these tests, are assumed to be constant. Moreover, 2D classical curves given by some constructors can be reconstructed, such as mass flow gain, pressure gain and mass flow characterization. Secondly, an approximation of the mass flow stage characteristics of this five-way proportional valve by a polynomial function is described. The model elaborated enables a good reproduction of the pressure gain and the global mass flow characterization curves to be obtained.

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The paper presents the design and the construction of the power part of a three-way pneumatic valve that uses a pilot stage developed by Belforte et al., based on a compact turbulent amplifier that uses the laminar-turbulent transition of fluidic jets. The valve can be used to drive a power stage of pneumatic circuits. It has a low energy consumption to switch. The pilot stage uses an acoustic signal generated by a piezoelectric device to brake the laminar flow. The power part of the valve has been designed to obtain an high conductance and a good dynamic performance. The design of the power valve, by a mathematical model using concentrated parameters, is presented. The prototype was constructed and tested. The results of the experimental test are also reported and discussed.

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In this study, firstly, we have modeled a system consisting of various electro-mechanical and mechanical subsystems. The appropriateness of the model has been verified by simulation. The simulation model resolves the motion of spool, the winding current and the magnetic force. Also, we have calculated the displacement and velocity of the spool, flux contour line, b vector, flux density, flux linkage and back EMI' etc. Secondly, a program for analysis the flow in the spool was developed, and a study was conducted on the flow rate of the nozzle depending upon the pressure ratio between the upstream pressure and the downstream pressure, when the valve is fully open in the spool and the flow force depending upon a displacement of the spool in the valve. Further, the performance of pneumatic servo valve has been verified through an overall performance test on the developed product.

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This study was conducted to analyze the special quality of a very low power consumption type of pneumatic on-off micro valve, and to numerically investigate its flow characteristic depending upon a change in stroke. As a result, it was identified that an enough electromagnetic force (2.4N) acted on the solenoid so that the poppet of the micro valve might run a stroke (0.3 mm) at the high response speed (5ms), and that the yoke caused no magnetic force to be emitted. It was identified that the dynamic presstre acting on the poppet wall was little reduced when the poppet stroke was 0.4 mm or less, but that as it got to be beyond 0.4 mm, it was remarkably reduced and when it was 0.8mm, it went down to 40%.

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The simplified test model of the commercial reciprocating compressor for an automotive air-conditioner is used to measure the displacement of the suction valves using a strain gauge and to investigate the velocity distributions of the discharge flow from the valves using the particle image velocimetry sytem. This paper is focused on the effects of shape of the suction valve on the vibration-reduction. The size of the suction valve hole and the width of the tip of the suction valve are changed as main parameters of the valve shape. First, the size of the conventional valve hole and the width of the tip of the conventional valve are changed and seven new valves are manufactured to reduce the vibration of the valve. Next, the influence of the natural frequency on the vibration-reduction isinvestigated using one shape of the new valves by changing the material and the thickness of the valve. Finally, the reason of the vibration-reduction for one shape of the new valves is discussed from the results of the flow analysis around the valve. The vibration-reduction for one of the new valve is confirmed by measurement of the displacement of the valve in the reciprocating compressor.

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Recently, unsteady flow rate measurement of gases is very important in the various industrial fields. However, there is no way to calibrate and to examine the unsteady flow rate of gases experimentally. As a result, there is no test bench for the unsteady fl ow rate measurement of gases.
In this paper, we developed a new type of unsteady flow generator for gases. Especially, we realized to generate the unsteady fl ow of gases continuously. Then, we verified experimentally the generated unsteady flow rate using a laminar flow meter that has quick response up to 50 [Hz]. Moreover, we investigated the heat transfer in the generator. As a result, we confirmed that this generator could generate the oscillatory flow up to the frequency of 30 [Hz], and the target flow continuously for 30 minutes. The generator is effective for the verification of the various unsteady phenomena of gases experimentally.

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The Lab. simulator for conducting a performance test and a reliability test on a vehicle and components has been designed and embodied. In order to control non-linear of a vehicle, a fuzzy control algorithm, a running mode tracking algorithm and a vehicle speed control algorithm were applied to the actuator control. The vehicle controller functions were implemented; setup of the actuator, position control, the gear shift control depending upon the vehicle RPM, the serial interface function for data communication and control with the servo controller, and transmitting and receiving data. The servo controller performed the function to drive the actuator by controlling the pneumatic servo valve, and measured data information such as a position, a velocity and an acceleration as obtained through operation by means of the second differentiator and controlled a position precisely. An experimental apparatus was consisted of a dynamometer and a vehicle, and the performance and durability of the controller was verified. The Lab. simulator was mounted onto the vehicle, and the position control test and a LAP mode tracking test were conducted. It was found that the response characteristic, the tracking capability and precision of the position control were so excellent.

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Pneumatic cylinders can not usually retain steady motion when a low speed is required because of the stick-slip effect. Stick-slip is a kind of motion in which the piston stops its motion intermittently because of the friction force. In this paper a neural network (NN) classifier is set up as a new method to predict the occurrence of stick-slip by different dynamic working parameters.
The classifier is made of an NN, and the training samples come from the simulation. It classifies different working conditions into two groups: stick-slip will occur and stick-slip won't occur, without concerning the process and the model. The NN is based on a back-propagation (BP) neural network. The input variables may be single variables of the dynamic working parameters or the combinations of them and the output variables are the two groups.

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Compressible flows between two parallel disks are frequently encountered in fluid power components such as pneumatic statistical bearings, pneumatic nozzle-flapper valves and pneumatic valves. Such flows are difficult to solve theoretically because both viscous and compressible effects exist. In the present study, a theory is developed to predict the flow characteristics, assuming that the flow is one dimensional and steady. Experiments are performed, and their results agree fairly well with theoretical results.

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