We have reported that a pneumatic finger [1] can work in the field of human tasks, such as paper handling. In this field, to know the “Human Sensitivity” is becoming increasingly important. There are manyfactors which influence human sensibility, and we measured the physical information of material affect on human recognizing by using artificial fi nger [2] having force and temperature sensors. Also, we constructed a Neural Network [NN] system which represents a human feeling and then these physical information are applied as the inputs of theNN system. After the learning against many materials, the outputs of the NN can have images like a human.

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In this paper the design and the manufacture of a knee orthoses is presented. The orthoses is designed to help the elderly or disabled people to stand up and to sit down on a seat. The specifications of the orthoses' design include the low weight, the small overall dimensions, and the possibility to be worn under the trousers. The orthoses uses two McKibben pneumatic muscle actuators as drivers. These actuators were modified inserting a spring to grow the traction force. The orthoses has been manufactured and some preliminary tests with a healthy person were carried out. The results are encouraging and suggest other work to optimize the device.

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Recently a number of immersive displays that project virtual environment on large-sized screens have been developed. In applications of virtual reality technology for such large immersiveenvironments, it is important to develop some haptic display that gives a real feedback sensation such as forceor tactile to users from the virtual environment. Especially, it is necessary to develop small, light and safety actuators for the wearable haptic display. In this paper, the haptic display system using pneumatics for theimmersive virtual environment is proposed and developed. The system consists of a tactile and a force reflecting type wearable haptic displays using pneumatic pressure control. Experiments for grasping virtual objects in the virtual environment are performed by the wearable haptic displays using pneumatic actuators. It is experimentally verified that the performance of the haptic display system is effective to touch and grasp the virtual objects.

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In this study, we aim at developing a device that can display compliance property of an object for human fingertips. Pneumatic actuator is focused to be employed as our displaying device from view that pneumatic actuators bring minute force control property owing to the air compressibility. Concretely, pneumatic cylinders are set on a base plane with their head side edge by flexible joint, while their rod side one is connected with fingertip directly to display force feeling by regulating pressure in cylinder's chamber. Compliance control system is constructed on the developed displaying equipment. The validity of the proposed system is confirmed through some experiments and analysis.

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When elderly people use welfare machines or rehabilitation machines, they lean on the supporter of the machine. Since the user hold the supporter at the same locus to prevent slipping from the supporter, they sometimes feel pains at the contact point. In this paper, we propose a new type of active supporter (Silicon Outer Fence Mold Actuator) which sponge is covered with silicon rubber. Since the stiffness of the active supporter is controlled by pressure in sponge chamber, it is possible to change the contact point of the body. From some experimental results, it is clarified that characteristics of the active supporter are influenced by the sponge layer structure. Furthermore, in order to indicate the effectiveness of the active supporter, we measure heart rate of the subject as an evaluation of the burden degree of the body.

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Pneumatic cylinder is widely used for mechanical handling systems. Often, the impact occurs at the both ends points of pneumatic cylinder and generates the destructive shock with in the structural operating members of the machine or equipment. To reduce the damage of system, therefore, shock absorbing devices are required. Cushioning of pneumatic cylinders at one or both ends of piston stroke is used to reduce the shock and vibration. The cylinder body have to withstand under conditions of high velocity and load. In this research pneumatic cushioning cylinder moving tests have been conducted for different load mass and supply pressure. The velocity of pneumatic cylinder actuation system which is set vertically with multiple orifice cushion sleeve is controled with the meter-inlout control system. This study examines the dynamic characteristics of pneumatic cylinder which are used as cushion devices. It turns out that the cushion pressure is mainly a function of the external load rather than the supply pressure. The cushion region characteristics was also revealed in the meter-in control system.

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In this report, we have developed a pneumatically assist system for human walk who has a handicap or damage. The assist system supports the human leg force by using pneumatic linear actuators when he desires to stretch his knee joints. The supportable angles of knee are enough wide and the system can be used in the range of stand up and go up/down stairs. This system consists of two outfits of each leg actuated by pneumatic linear cylinder and a pair of shows having the weight sensors on the sole. When the human tries to move, the force change is detected by sensors on shoes and the deferent signal forms in the various conditions, i.e. he attempt to walk, go up/down the stairs and stand up from chair, are used to decide the assist timing of each assist control mode. The usefulness of this system will be evaluated by the power reducing ratio of human and his impression for use.

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In this paper the dynamic model of a pneumatic system containing an air cushion cylinder is built by using bond graph method. Bond graphs are extended to deal with non-linearities and multiports in the form of equations by using the language SIDOPS+. Simulations are carried out with different working parameters such as openings of cushion needle valve. Simulation results are verified by experiments. Finally, an optimal opening of the cushion needle valve under a certain working condition is obtained by running multiple simulations with parameter sweep. The bond graph simulation can help to predict the performance of the air cushion and to determine the optimal opening of cushion needle valve.

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This paper discusses the energy consumption characteristics of electric and pneumatic actuators at reciprocating motion, and then makes a general comparison between the two types of actuator. After determining actuator models with the most used size, energy consumption is investigated at their horizontal and vertical cyclic actuations. It is found that electric actuators need a fixed amount of fundamental power even when they do not move. The fundamental power is used for operating controller and holding load. It is also found that their average efficiency at reciprocating motion is only half of the general specific efficiency of motor. Compared with electric actuators, pneumatic cylinders show a good characteristics that only little of power is consumed for valve driving and air leak at the stopping state. Therefore, when the stop time is relatively long, a pneumatic cylinder is more efficient. It is concluded that it is a misunderstanding to declare that a pneumatic cylinder is certainly inefficient compared with an electric actuator. Actuation condition should be considered when selecting an efficient actuator.

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In mechanical manufacture, air jet is often used to remove the water droplets, particles and residues from workpieces. However, an obvious disadvantage has shown in the energy dissipation caused by the vast flux of air supply. With the purpose of protecting environment and saving the energy, the removal efficiency of water and particle has been concerned.
In this paper the image method of evaluating particle removal and water removal efficiency are presented. Influence of impinging angle, supply pressure, nozzle-plate distance (between the exit of nozzle and impinging plate) on removal efficiency is studied systematically. The results of our experiments show that the efficiency of particle removal and water removal increases with increasing supply pressure. The efficiency of particle removal varies with impinging angle and nozzle-plate distance, optimal ranges can be obtained from these experiments. However the efficiency of water removal is not sensitive to the impinging angle and the nozzle-plate distance

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For pneumatic system controls, a data transmission system is needed with high speed and reliability for information interchange between main computer and I/O devices. This paper presents a set of design techniques for a data communication system that is mainly used for pneumatic system controls. For this purpose, we first designed hardware modules for an interface between the central control module and the local node that handles the operation of solenoid valves. In addition, a communication protocol is developed for construction of RS-485 based multi-drop network, and this protocol is basically designed with a kind of polling technique. Finally we the performance of the developed system is evaluated. The field test results show that, even under high noise environment, the data transmission of 375Kbps rate is possible up to 1, 000m without using repeater. In addition, the system developed in this research can be easily extended for a communication network because of its modular structure.

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In designing pneumatic systems, how to select matched models which meet requirements easily, swiftly and appropriately becomes increasingly important from the point of view to reduce the designing time and cost.
In this paper, an optimum model selection tool for pneumatic systems named Pneumatic Model Selection Program (PMSP) will be introduced. If a user inputs some requirements, the program automatically selects matched models such as cylinder, valve, speed controller, piping and shock absorber. If the user inputs a circuit and part number of components, the program calculates. the dynamic performance of the system and indicates various characteristics such as full stroke time, stroke end velocity and air consumption. Besides, the user can also calculate the cushion ability of the cylinder and the condensation probability of the system by using this program.

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Electro-Pneumatic sequencial circuit (EPSC), which controlled by PLC takes as important role in all kinds of production lines. An easy method to design this kind of EPSC is put forward in this paper. Based on this method, a CAD software for EPSC, named PneuCAD that allows users to design, simulate and animate circuits consisting of electro-pneumatic sequencial systems. PneuCAD is the ideal CAD and simulation tool for teachers, students and engineers who specialized in pneumatics.

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Energy saving is an important issue for pneumatic systems. The pneumatic system is difficult to determine its precise mathematical model, thus modeling error should be taken into account in its control. In the view point of robust control, improvement of energy efficiency has been discussed in the paper. Energy efficiency is the ratio of input energy to pneumatic actuator and to the load. This problem cannot not be treated in the H∞ control directly, and modified mixed sensitivity problem based on dynamic impedance matching is proposed. Simulation results verifies the effectiveness of the proposed method.

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This paper presents the interest of including control strategy into electropneumatic design. For this certain experimental results obtained in an electropneumatic process have been presented. Using two servo-distributors leads to a system with one degree of freedom. This opportunity is exploited for in two objectives. The first concerns positioning control and the second attempts to optimise energy efficiency. With this aim an energy optimisation algorithm has been presented. The chosen control algorithm issues from the flatness concept.

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This paper shows how to analyze the energy efficiencies of typical pneumatic equipment. Firstly, a proposed new item, air power, is introduced as the quantitative standard of energy in compressed air. Then, a pneumatic system is divided to the four parts: air production, cleaning, transmission and consumption for discussion. In air production, compressor including cooler is discussed. After discussion on the overall adiabatic and isothermal efficiencies, the overall efficiency of compressor is defined with air power and proposed as the final energy-conversion efficiency. In air cleaning, energy efficiencies of air dryer and filter are investigated and their general data are given. In air transmission, the energy losses due to pressure loss in pipe and air leaks are discussed, and the energy saving effect of a regulator is shown. In air consumption, the energy distribution in a cylinder actuation is clarified. The efficiency analysis methods discussed in this study will be greatly helpful to an energy-saving equipment selection.

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Reduction of the energy consumption of the equipment is being attempted in the each industry field in order to protect the global environment. The protocol incorporated that the goal of prevention from global warming conference held in Kyoto in December, 1997. Efficiency improvement over 8% is also required on the pneumatic system. Main things of the reduction measures of the air consumption are as follows.(1) Air consumption in the pneumatic driving system is reduced.(2) Reduction of the pressure loss is done, and air leakage countermeasure.(3) Pressure reduction of the air blow is advanced. This study is to propose the method of drive does not use the speed controller. Since the speed control valve is not used, the relationship between adjustment of the speed, size of load mass and the level of supply pressure was examined experimentally. As the result, the drive using this method was possible, and it was proven that the air consumption was also less than conventional driving method.

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There are various governmental and industry pressures on the fluid power industry that necessitates substantial improvements in fluids and materials used in the fluid power industry. For example, substantial improvements in fl uid lifetimes, especially oxidative stability at higher use temperatures and dramatic improvements in biodegradability and toxicity for mineral oil fluids is vital. Another very important and continuing market and technology thrust in the fluid power industry is in the development of alternative hydraulic fluids whose performance will rival that of petroleum oil. Substantial improvements in the materials used in hydraulic systems with respect to corrosion and antiwear performance is vital. In fact, it is impossible further ignore the fact that the hydraulic fluid must be considered as a design component of the hydraulic system. This itself is a relatively recent focal point. An overview of these and other technology thrusts will be discussed. The focus of this discussion will be on the development of biodegradable fluids.

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A simple control valve using a magneto-rheological (MR) fluid has been proposed and called the MR valve. The MR valve utilizes the apparent viscosity controllability of the MR fluid in the magnetic field and controls high-level fluid power without moving parts. However, conventional MR fluids have high base viscosities to disperse heavy soft iron particles and lose fluid power in pipes. In this study, low base viscosity MR fluids aredeveloped using lightweight ferrite particles and applied to a bellows-driven motion control system. First, four MR fluids are fabricated with different compositions and the basic characteristics are experimentally investigated. Second, a small-sized three-port MR valve using a permanent magnet is proposed and the most suitable MR fluid is selected through theoretical evaluation to minimize the valve size. Third, the three-port MR valve is fabricated and applied to a bellows-driven motion control system.

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Cavitation commonly occurred in hydraulic components is generally regarded as harmful phenomena in the hydraulic control systems, because the collapse of the cavitation bubbles could induce the vibration, noise and some times even corrupt severely the surface of the elements. Motivated by a desire to suppress cavitation induced noise in hydraulic control valve, the objective of this work is to study the inception of the cavitation and to evaluate the effects of internal structure of the valve on cavitation intensity as well as cavitation noise. In the presented paper, the computational fluid dynamics and flow visualization approaches are used to obtain static pressure distributions and cavitation images in the channel of the main stage of the relief valve. The predicted low-pressure regions and gas volume fraction of cavitation agree well with the observed cavitation areas. The noise level from the traditional and optimized internal structures of the relief valves are tested and compared.

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This paper presents the development research of a unique flow meter utilizing fow force. This flow meter makes use of flow force by appropriately laying out the inclined plate or tapered shaft in a flow line to generate torque. The feature of this flow meter is as follows:(1) The structure is simple.(2) The pressure loss thorough the flow meter is very small.(3) The flow rate can be instantaneously acquired by measuring torque; thus a good dynamic response can be expected. In this paper, the fundamental principle and the mathematical model of the present flow meter are described. Then as the first step of the development research, the fundamental characteristics for asteady state are investigated theoretically in order to obtain the design criterion. In addition, based on thisinformation, the dimensions of the proposed flow meter are derived as example design cases.

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When oil flows through a pipeline, and the flow is stopped suddenly, very high pressure is generated. This is called an oil hammer phenomenon. We are developing a device to intensify pressure using an oil hammer. We succeeded in obtaining several times higher pressure than supplied one. When high-pressure is necessary, this device can turn low pressure into high pressure. Therefore, a hydraulic pump can be smaller, and saveenergy. The purpose of this research is to help apply this device to industrial machinery. To apply it to an actual machine, the necessary level of increased pressure by an oil hammer is about 30MPa. We intend to find a suitable pipeline length, diameter, and line shape, in order that low pressure supplied by a pump may be increased to high pressure.

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The objective of the research project, the subject of this paper, is to develop ahybrid diesel-hydraulic drive for large commercial vehicles e.g. urban freight delivery, buses or garbage trucks. The system incorporates a Regenerative Drive Shaft (RDS) which consists of a variable pump/motor coaxial with the drive shaft.Hydraulic energy is supplied to the wheels of the vehicle in parallel with energy supplied by the truck drive system.The objective is to store/supply energy to assist truck braking/acceleration.The unit works as a pump during braking of the truck and thus performs two functions- it stores energy in the accumulator and at the same time provides hydrostatic braking. When the truck accelerates the pump operates as a motor assisting the truck engine. The major advantages of the proposed RDS system over other systems is the application of microprocessor control to optimise power utilisation and elimination of losses during transfer of energy between the truck drive system and the hydraulic pump/motor. This technology offers additional advantages of lower noise, increased reliability, lower maintenance costs and a substantially reduced environment impact. The paper presents and discusses the development of the system, modelling approaches and the results of preliminary performance tests on 10 ton vehicle.

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This paper focuses on the Variable Structure Control (VSC) of an electro-hydraulically actuated friction damper suspension system for a motor vehicle. Four controlled servo-driven dry-friction dampers replace four conventional passive viscous dampers. A model of the vehicle and of the hydraulic drive is developed, a multivariable controller is designed and performance investigated via computer simulation. With a controller designed to improve bounce motion the semi-active system is predicted to have superior performance compared to a passive system in response to sinusoidal road input. Less clear cut benefits are predicted when the system is subjected to roll, random and bump inputs. Future work needs to focus on and-roll control schemes.

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In this paper, a vision sensing system was developed in order to measure the gesture of the construction machine and the cylinder displacement of each actuator. The system consists of a single CCD video camera and several light sources which were used to acquire the distance information of key points of the construction machine. The three-dimensional coordinates of key points were obtained from a two-dimensional video image by using image processing. The gesture of the construction machine and the cylinder displacement of each hydraulic actuator were calculated via the inverse kinematics method. In addition, the validity of the proposed method was confirmed through an experiment of parameter estimation for the friction characteristics of a hydraulic cylinder.

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The transmittable power of continuously variable belt- and chain transmissions has been increased steadily in recent years so they have the potential for use in tractors up to about 100 kW. In the current common designs, the hydraulic system, which is required for clamping and ratio control, exerts a strong influence on the total losses. In order to increase the overall efficiency of such a transmission, new, pressure-controlled clamping hydraulics with significant higher efficiencies were examined with the aid of computer simulation. Among an expensive but exact solution a simpler approach is introduced. These studies focused on the realization of highly dynamic clamping pressure supply in cases of sudden torque increase, which occur frequently in tractors.

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Anti-lock Braking System (ABS) is a safety device for preventing wheel-locking in a sudden braking. It consists of hydraulic modulator, ECU and wheel speed sensors. The hydraulic modulators are classified into two types; sot-flow type and sol-sol type. In this paper, the hydraulic modulator is composed of one solenoid valve with 3way-2position. The braking friction force described by function of slip ratio can obtained maximum value if slip ratio cartbe maintained from 0.1 to 0.3. Consequently, slip ratio is controlled by PWM and SMC based on vehicle dynamics in the same way a two-level control scheme.

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A new type of control architecture for hydraulic teleoperation systems called parallel impedance control is proposed. It is completely different from the conventional bilateral control, which couples the master and slave manipulator as an entity to realize an ideal tool for the operator. The key ideal of our work is that the slave manipulator should mimic the abilities of the operator. The hydraulic teleoperation system is partitioned into an operator-master part and a slave-object part to produce parallel two subsystems such that the slave manipulator can emulate the operator and the master manipulator can transmit the object impedance encountered by the slave manipulator to the operator, thereby providing transparency. The proposed control architecture is applied to a hydraulic teleoperation system and its validity is proved by the experimental results.

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The motion of six servo cylinders of parallel link mechanism induce a coupling motion in each other and causes the deterioration of control accuracy. The characteristics of these coupling motion is analyzed by frequency response and modal analysis. The result of frequency response shows that the effect of coupling is remarkable in high frequency region, especially at resonance frequencies. The result of the modal analysis makes it more simple to investigate the complicated characteristics of the high order system dynamics.

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This paper introduces a new type of parallel mechanism that have a telescopic structure and motion capability in 3DOF. The forward and inverse kinematic analysis is given. The velocity model is derived, the inverse dynamic model includes hydraulic dynamic model are presented, one potential application is suggested.

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We previously developed a six-DOF parallel link force display that is actuated by six hydraulic cylinders. The manipulability of the display, however, was insufficient at first, because the dynamic performance of each cylinder was not necessarily the same as that of the others. To overcome this problem, in the present study we have applied disturbance compensation to improve manipulability. To demonstrate a practical application of this force display, we also have constituted a master-slave system in which the display is adopted as the master and the same type of hydraulic manipulator is adopted as the slave. An operator manipulated the system so thatthe slave touched a flexible object serving as a load. Our experiments confirmed that the system was controlled with relatively good dynamic performance and that the operator was able to feel the load force sensitively through the force display.

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Frame of motorcycle receives complicated force and moment in actual running. Some time, damage is considerable and motorcycle component failure takes place. This is very dangerous and efficient test method is desired. But application of conventional test method of single or multiple actuators is difficult, because test object is relatively small and fragile. In this situation, we developed new method of load test using parallel mechanism. Advantage of this method is possibility to generate any assigned force or moment vector at desired small point. That is, combined skew force or three-axis moment test becomes possible by only software change. We actually designed practical parallel mechanism actuating system for motorcycle. End-effector force and moment vector are converted to cylinder pressure command by Jacobian matrix method.

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This contribution reports about some analytical and simulation/experimental studies carried out on different flow control systems for mobile applications with respect to their ability to do flow sharing. All systems have two parallel actuators and are considered regarding functionality and complexity. The aim is to compare well established systems/methods and systems involving electronic sensor technology.

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A quick response injector has a potential to improve exhaust gas emissions. This paper describes performance of a newly designed pilot operated proportional injector for a common-rail diesel fuel injection system. The main needle valve is positioned by a hydro-mechanical servomechanism with feedback slot for continuous flow-rate control, and the pilot valve is operated by a tandem arrayed giant-magnetostrictive actuator for linear motion control. The injector discharges flow-rates up to 30 mm³/ms linearly to electric current at 160MPa pressure within on/off lag time of 0.35ms (on) and 0.5ms (off) by using a nozzle of 6 holes x 0.16mm in diameter.

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This article introduces the operating principle of 440t self-made oil press and presents the methods of resolution after having analyzed the serious noise problem in the adjustment process. In this paper, we propose to choose a high flow capacity overflow valve to replace the two same type overflow valves; to make far distance between the fluid influx site and outlet of pumps; to install a standpipe at the return line entry of overflow valve; to adapt low noise overflow valve. The noise is obviously lower than the past after the modification and the system is operated normal.

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This paper deals with linear analysis of a conventional hydraulic power assisted steering system for passenger cars. The reason for this study is to be able to transfer the steering feel information transmitted to the driver, as well as, the frequency dependency of the assist characteristic of the system to other types of steering systems. Such systems could be electric power assisted steering (EPAS) systems, as they have lately been introduced on smaller passenger cars. In this paper, several relevant transfer functions of the conventional power steering system have been derived and the underlying control structure of conventional hydraulic power steering systems are discussed.

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In this paper the cross sectional area of a hydraulic servo valve is modelled as a non-linear function of the spool position. The actual leakage flow between the work port and the tank as well as between the work port and the supply port is measured. The leakage flow is modelled based on an idea of a separate pressure drop factor for the flow through the notches and the flow in the gap. The actual leakage flow to the tank is subtracted from the measured flow and the actual leakage to the work port is added to it. The discharge coefficient in the theoretical turbulent flow equation is fi tted to the remaining flow curve and estimated volume flow is used as a velocity feedback in a hydraulic cylinder velocity servo.

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In this study, we developed a construction tele-robotic system that has wide applications in restoration work in stricken areas. The system consists of a servo-controlled construction robot, two joysticks to operate the robot from a remote place and a 6 DOF (degrees of freedom) motion base. The operator sits on a seat attached to the motion base. A vital problem that must be solved in such a system is how to convey adequate presence of working site in a high quality simulation to the operator. In this paper, a control method employing the 6 DOF motion base is investigated to generate 6 DOF realistic motions according to the signals of six acceleration sensors on the construction tele-robot. The validity of this method has been confirmed experimentally, i.e., not only can each motion (roll, pitch, yaw, surge, sway and heave) of the construction tele-robot be simulated accurately by the 6 DOF motion base, but also this complex motion can be simulated in high quality.

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This study deals with a master-slave system of a tele-operated construction robot. The system consists of an excavator as the construction robot, and two joysticks for operating the robot from a remote place. A fork glove is equipped with the front end of the excavator as a hand for grasping task objects. The master and the slave in this system correspond to, respectively, the fork glove and the joysticks controlled by an operator. In such a remote control system, the operator needs to feel a realistic sense of task force which is brought about from a feedback force of the fork glove. In order to attain an effective feedback of the task force, in the previous report of this study, a control method called a variable-gain symmetric-position was proposed. After that, however, a weak point was found in this method. Namely, the operator was not able to feel a realistic sense of the task force when he was grasping a soft object in comparatively a slow velocity. In the present report, therefore, for overcoming this problem, an improved method of control in comparison with the previous method is proposed.

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This paper demonstrates that hybrid neural-genetic multimodel parameter estimation algorithm can be applied to structured system identification of electro-hydraulic servo system. This algorithm are consist of a recurrent incremental credit assignment (ICRA) neural network and a genetic algorithm. The ICRA neural network evaluates each member of a generation of model and genetic algorithm produces new generation of model. We manufactured electro-hydraulic servo system and the hybrid neural-genetic multimodel parameter estimation algorithm is applied to the task to find the parameter values (mass, damping coefficient, bulk modulus, spring coefficient) which minimize total square error.

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The oil hydraulic cylinder has been used as industrial actuators, because it is inexpensive and also has a high power to weight ratio. However the accurate control of the oil hydraulic actuators is difficult because of very complex and high nonlinearity due to flow-pressure relationship and large friction force. Recently, to overcome those problems an impedance or hybrid force/position control concept has been suggested. This study proposes an impedance control of an oil hydraulic servo system with a position-based approach where an optimal servo system using the LQ optimization technique is constructed inside the force feedback loop. And also to attain the desired impedance over extensive operating conditions, we use an impedance parameter modulation law. From some experiments, an impedance parameter modulation law incorporating the optimal servo system shows good static force control ability and excellent performance in dynamic tasks such as collision force reduction.

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An axial piston hydraulic motor with a tripod joints mechanism is introduced to improve compactness and starting torque in conventional types of motor. If the mechanism is applied in transmission torque to motor shaft, its friction torque loss would be drastically reduced and mechanical efficiency would be improved because the motion of tripod joints mechanism is relatively smaller than that of the conventional plunger motor. In particular, kinematics analysis for the mechanism is done as a preliminary study to investigate the feasibility of the mechanism in the axial piston motor. General formulas are derived from the displacement and velocity analysis of that mechanism, showing relationships between output shaft and shoe holder motion. A series of numerical calculations are carried out for a medium size motor with 160cc/rev using the formulas and their graphical plots are shown as well.

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This paper presents an investigation of the torque losses in a hydraulic motor of radial piston type commonly used in industrial hydrostatic transmissions. When the speed of the hydraulic motor is decreased an increase of the torque loss can be measured. In order to investigate the reason for this increase a combination of experimental and theoretical studies are performed with special focus on two sliding contacts-the distributor valve and the piston-cam roller contact. The theoretical analysis of the contacts reveals that the distributor valve contribute more to torque and power losses compared to the piston-cam roller contacts and largely to the external leakage of the motor. At low speeds the pistoncam roller contact will enter the mixed lubrication regime.

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The present paper reports a high-speed motor driven by fluid power. The torque produced by a flow supplied to the motor generates high-speed rotational motion. Bend channels of small diameter in the motor's rotor produce the torque. The fl ow in the bend channels generates a large change in angular momentum to produce the torque. The advantages of the highspeed motor are a simple structure and the absence of large frictional forces acting on the moving elements of the motor. These advantages allow the motor to be driven by not only air flow or oil flow, but also water flow. In the present paper, a mathematical model is first derived, and then two design procedures, a power-based design procedure and an efficiencybased design procedure, are presented. Finally, the characteristics of the motor designed using the power-based design procedure were measured experimentally and then compared to results obtained via simulation.

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In this study, the system that can automatically test comprehensive performance in the hydraulic motor and can be used as test equipments for the development of the hydraulic motor is designed and developed. The effort focuses on the development of test software that analyzes collected data from the hydraulic motor and evaluates its performance, and further on building of test equipments. Test items consists of 12 including the efficiency test, and these tests are carried out full automatically. In particular, the volumetric test is, in general, done by separating the loading part in the hydraulic motor, but here it is carried out through unloading conditions only by controlling the charging pressures in this system. In controlling the test equipment, both open loop and closed loop controls are applied resulting in stable, fast, and accurate test conditions. This system includes not only function of performance test but also capability of calibration and self diagnosis. It also involves 3D graphic contour map plotting and analytical techniques.

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The kinematic design methodology of a proposed hydrostatic machine [1] which comprises of (i) multi-piston pump with each chamber connected to corresponding chamber, with flexible or rigid piping, of an orbital rotary piston (ORBIT**) motor, (ii) a charge pump to compensate leakage and (iii) necessary circuit and valves, is presented. It works on the principles of alternating flow hydraulics (AFH) and hydrostatic transmission (HST) with Orbital rotary piston machines (ROPIMA). Earlier AFH-HST systems with cylindrical piston pump and motor, having transmission ratio of 1: 1, exhibited high efficiency in comparison to the DC HST of same capacity, as there is less loss due to the absence of flow distributor valve [2, 3]. Torque amplification is a unique additional advantageous feature of the proposed machine. The transmission ratio i.e., torque amplification or speed reduction ratio equals to the number of phases (piston) or one less depending upon the kinematic arrangement. A prototype is made and some aspects of performances are studied. It's possible application ranges from reduction unit in general to the articulated joint such as robot wrist actuator etc.

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The main goal when designing a demanding hydraulic cylinder servo drive is to increase damping and avoid strong disturbances. Effective damping is increased with suitable control algorithms. Different profile generators are used to smooth the position reference and avoid heavy disturbances. Motion control is typically applied to applications with heavy demands on static and dynamic performance. Of all application parameters the inertia load has the strongest influence on the dynamics of a cylinder drive. In this case the motion control is an application where different inertia loads are transferred from one point to another by various programmable strokes and velocities. In this paper the influence of various inertia loads on the robustness of a hydraulic cylinder drive is presented. Dynamic behaviour as well as, position and stroke time accuracies are used in the estimation of experimental results, when different inertia loads are applied. The benefits and drawbacks of different motion profiles are discussed.

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The system treated in this paper is a model of a moulding press for a fabrication process of LSI packages. Performance of force control is important to obtain sufficient quality of the moulding. Considering uncertainty caused by flow characteristics of a servo valve and mechanical stiffness of a frame of the press machine, a method of designing a robust force controller by applying H infinity control theory is proposed. Performance of the robust controller is examined using an experimental setup of a water-hydraulic servo system

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In case of restricting the relation between the parents and the offspring as each one in order to learn in real time, a new numerical formula is proposed to solve the difficulty of adjusting the search region as reducing the individual by using the error generated from the sensor of the dynamic system. The mutation equation of evolutionary strategy uses the error that is generated from the dynamic system. Competitive individuals among total population are reduced with automatic adjustments of the search region in accord with the error. Therefore, it is possible to control the control object varied as time changes because control signal of the learning is generated in real-time. As the state value of the control object is generated, evolutionary is applied strategy each sampling time because the learning process of an estimation, selection and mutation is done in real-time. These algorithms can be applied; the people who do not have knowledge about the technical tuning of dynamic systems could design the controller or problems in which the characteristics of the system dynamics are slightly varied as time changes.

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The position control of a hydraulic cylinder using a constant pressure system is studied. A hydraulic transformer based on FFC pump/motor is used as a control component to drive the cylinder with a load vertically. The transfer function from displacement of the variable displacement motor to the cylinder position is derived and PID controller and feedforward controller are designed and implemented. With these controllers the torque loss and the leakage of the transformer can be compensated and the sufficient accuracy of positioning is obtained.

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