In this paper the characteristics of disk type hydrostatic thrust bearings supporting concentric loads, simulating the major bearing/seal parts of water hydraulic pumps and motors, are presented. The bearing is made up by combination of stainless steel/stainless steel and stainless steel/plastics. The characteristics are evaluated by the relationship among the load capacity, pocket pressure, film thickness, and leakage flow rate. The main results are as follows: 1) the load capacity expressed by the ratio of hydrostatic balance is not only dependent of the supply pressure (with the same restrictor) but also of the elastic modulus of materials, 2) effects of inlet pressure drop into the bearing land are much smaller than those of elastic deformation, especially in plastics, 3) the calculated results coincide well with the experimental results.

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The main aim when designing a controller for a demanding water hydraulic servo application is to find a good and practical method for increasing system damping. The low natural damping of water hydraulic cylinder drives has to be carefully considered also in open loop control applications. The damping of a cylinder drive depends on many factors. Traditionally, mainly based on the linear model, damping is considered to result from viscous friction force. However, if viscous friction force were the only factor achiving damping of a system, it should have to be unpractically great. In this paper the effects of the main factors influencing the damping of water hydraulic cylinder drives are studied on the basis of experimental data and simulation. The individual effects of these factors are studied by comparing simulation results with experimental open loop velocity and pressure measurements.

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High and medium pressure water hydraulics is widely used in various industrial applications. In applications where extreme environmental safety is needed and in applications in fire hazardous environment water hydraulics has been proven to be the best solution available. However, component costs in high and medium pressure water hydraulics are relatively high and therefore they are often substituted by other methods of power transmission. Other alternatives, such as conventional oil hydraulics, pneumatics and electric drives, however always lack some qualities water hydraulics could offer. To offer a technically competitive and cost effective alternative for them, the possibility of using low pressure and relatively cheap materials and components, such as centrifugal pumps, in water hydraulic system was studied.
Test systems were constructed using centrifugal pump, pneumatic cylinders and ordinary plumbing components, including rigid PVC-tubing and PVC-hoses. The over all performance of systems was studied as well as performance and suitability of components.
Test results indicate that in applications where force required from actuators are not very high a low pressure waterhydraulic system can offer a competitive alternative to conventional methods of power transmission. In this paper we present comparison of low-pressure water hydraulics to other alternatives of power transmission. Power density, system efficiency, relative component and system costs and noise level are compared, based on measurements from test systems. Also pressure transients and other characteristics of systems were studied and are presented in this paper.

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The shear stresses of ER (Electro-rheological) suspensions are measured by changing a shear rate and electric fi elds (DC and AC) using rotational viscometer whose gap between electrodes can be changed. We use two ER suspensions which are called ERFC and ERFP. ERFC consist of cellulose suspended in silicone oil. The size of cellulose particles is typically about 10-20 μm and a viscosity of silicone oil is 10mm²/s. Cellulose concentration is 20wt.% and the percentage of moisture content is 0.6%. ERFP contains highly sulfonated poly (styrene-codivinylbenzene) particles. An average particle diameter of ERFP is 9 microns and the water content is 2.0 wt.%. Bipolar sine-wave electric fields (AC) are used and the shear rates of 400 s^-1 are employed. Amplitudes are between 1.0 and 2.5 kV/mm. The frequency of the electric fields is changed from 0.1 to 100 Hz. Dependence of the shear stress on electrical excitation frequency is investigated.

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The dynamic viscoelasticity of ER suspensions depends on the fluid strain amplitude, the oscillation frequency and the applied electric field strength. This behavior can be explained based on the formation and deformation of ER particle clusters that span the electrodes. In this work, changes of the fibrous structure of an ER fluid in an oscillatory slit flow are analyzed (by direct observation using an optical microscopic probe) when the electric field, the strain amplitude and the oscillation frequency are varied. The ER fluid studied in this work is composed of sulfonated polymer particles (5 vol%) in a silicone oil. The hysteresis loop of pressure difference as a function of strain is explained based on the visualization of the chain-like microstructure.

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A novel control valve using MR fluid (MR valve) is proposed for fluid control systems. The MR or Magneto-Rheological fluid is a newly developed functional fluid whose apparent viscosity is controlled by the applied magnetic field intensity wider than that of Electro-Rheological fluid. The MR valve consists of a flow channel between a pair of magnetic poles and the differential pressure is controlled by the applied magnetic field intensity. It features simple, compact and reliable structure without moving parts.
An MR valve is fabricated. The magnetic poles have 20mm×3Omm in face size and 3mm in gap length and are connected to an electromagnet. Through experiments on the static characteristics, it is found that the differential pressure is controlled by the applied magnetic field intensity under little influence of the flowrate, which corresponds to a pressure control valve. The differential pressure and output power changes of 0.68MPa and 20W are obtained with the input current and power changes of 710A-turns and 1.9W at the flowrate of 30cm³/s (1.8L/min).

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The purpose of this study is to develop a simple and practical handling system which can recognize, pick up and carry the object skillfully and quickly. We developed a compound pneumatic hand to pick up one by one objects which were stacked closely. This hand is composed of four soft grippers to grasp various types of object and an absorption pad to pick up one object. The soft gripper is made of silicone rubber and is driven pneumatically. Afl exible strain sensor was developed to detect a bending displacement of gripper. By installing it in the gripper, the hand can not only confirm the grasping of object, but also recognize the approximate size and stiffness of object at the moment when grasping. The hand is positioned quickly by three pneumatic cylinders. This paper describes the structure, operating principle and fundamental property of each component and how to search the position of object.

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The paper deals with the performances of a vehicular suspension with compressiblefluid, installed between the wheel hub and the carbody. The gas spring is connected to an auxiliary reservoir via a fluidic resistance. For a fixed value of the suspended mass the effects of the initial actuator's volume, initial pressure, cross section area of the actuator, size of the fluid resistance and auxiliary volume of the reservoir are analysed.

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In this paper, we propose the simultaneous optimum design method of structural and control systems for an active suspension using a sensitivity analysis. We deal with an analytical half-car model based on the experimental equipment which has a pneumatic servo type active suspension. Control design variables for the optimum design are feedback gains of optimal control and structural design variables are spring constants, viscous damping coefficients, cylinder sectional areas, piston strokes and a wheelbase. We confirmed that the simultaneous optimum design method is useful for the pneumatic servo type active suspension from the numerical simulation results.

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This paper presents an attempt for improving low speed characteristics of pneumatic actuators. When operated at low speed, the pneumatic actuators tend to have a jump start and a stick-slip responses. In particular after a long time rest, the response usually has a distinct jump start, which sometimes is not tolerable. To solve these problems, this paper conducts a theoretical analysis on the pneumatic speed control circuit and based on the analysis a new pneumatic circuit is proposed. The proposed circuit is a Meter-In control circuit with two pressure control valves added to keep the exhaust pressure at a high lever. The experimental results show that the proposed circuit is feasible for low speed pneumatic actuators.

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For the health care the blood pressure has often measured in a home. Until now the blood pressure has been measured when decreasing the cuff pressure, after the cuff is pressurized by the pump. A measuring time is shortened, if the blood pressure is measured in pressurizing the cuff, and the restriction or valve to decrease the cuff pressure is unnecessary. In this study, it was proposed that the blood pressure is measured in the decompression, and for development of this system it discussed some the problems and control methods. As the result, it has been possible that the cuff pressure is risen at the constant pressure speed by only controlling the input voltage of the pump. By applying this, the more human friendly sphygmomanometer is realized.

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This paper describes the experiments and the theoretical analyses about the pressure versus flow characteristics of a pressure control proportional valve with diaphragms. The effects of the valve springs, effective area of the diaphragms and flow force on the characteristics are analyzed theoretically and experimentally. Fairly good agreement between experimental and theoretical results are obtained. The experimental results showed that the shape of the diaphragm has some effect on the relation between effective area versus valve displacement, and then on the pressure versus flow characteristics. Changing the shape of the diaphragm, better characteristics are obtained experimentally.

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A new type of an asymmetric electro-pneumatic servo valve which is used as a hardware compensation of the system to make fast the response speeds is developed and studied. To develop a very high speed system, such as pneumatic force control system for a spot welding machine an asymmetric servo valve which downstream port width is two times of the upstream one is expected as a hardware direct compensation to compensate the system and to equalize the response speeds. The asymmetric electro-pneumatic newly designed servovalve was investigated here to provide asymmetric control flows as an important component in the pneumatic pressure control system for achieving high speed control. This paper describes the characteristics of this asymmetric valve, and we assured the effectiveness of this valve by the experiment.

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An optical servo system is a new control system which can be used in hazardous environments where electromagnetic noises and radiations exist. In our previous study, we have realized an opto-pneumatic control system which executed a cart positioning using optical control signals instead of electric signals in ahazardous area. However, the response of the system was slower than a usual electro-pneumatic control system, because the response time of the optical servo valve which converted optical signal to pneumatic fluid power was longer. In the next step, we have proposed an analytical model of the valve in order to improve the dynamics of the valve. In order to design the valve, it is necessary to analyze the characteristics of moving rubber membranes in the valve in detail. In this paper, we propose an analytical model of the membranes. And we investigate the relation between design parameters of the valve, such as an equivalent spring constant, damping coefficient and so on, and structural parameters of the membranes, such as a diameter and thickness.

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An opto-fluidic control system employing a laminar proportional amplifier was used to convert directly optical signal into fluidic signal by the thermal control of the supply jet's velocity distribution. It can work in hazardous environment because it doesn't use electric signals. A differential optical signal was introduced through opposing optical fibers into the light absorbing end sections of them constructing the opposing side-walls of the supply nozzle of the interface. The differential fl uidic output signal of the opto-fluidic interface was amplified by a three-stage laminar proportional amplifier gain block and turbulent proportional amplifiers.
In this study, opto-fluidic conversion characteristics were clarified by numerical analysis and by the experiments using a experimental model having the size of four times that of the practical opto-fluidic interface. The appropriateness of the analytical model was proved by the experiment using the large-scale experimental model.

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Needle valve is widely used for flow control in industry. Changing the flow area, which is a circular gap between the cone-shaped core and valve body, the discharge of flow through the needle valve can be controlled. The gap of needle valve is less than one hundred microns, which can be blocked up slowly by the tiny particles in the fluid for a long time. In this paper the quantitative relations among the reduction of discharge, size of particle, concentration of particle and opening of needle valve were studied. These results are worth for designing a new style lubricator with high precision. The particle's movement in the narrow slit was also' analyzed in theory and visualization.

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Efficient modelling of systems with gas filled lines is of great importance for modelling of complex pneumatic systems. Other application areas, which are of importance, are ventilation systems with heat exchangers, coolers, air conditioning or heat pumps. The basic physical relationships in pneumatics are well known. The contribution of this paper is to present models that can be used for efficient simulation of large-scale systems. This is achieved by using distributed modelling technique (or transmission line modelling). The benefits of distributed modelling regarding numerical properties are well known. The most important property is that it allows the system to be partitioned by the time delays present in transmission lines. In this way it is possible to solve the equations of a subsystem/components independently from other subsystems/components in each time step. As a by-product, long transmission lines, including inertance effects, can also be easily modelled.

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The experiment on frictional characteristics of pneumatic cylinders was performed. The inner diameters of the cylinders tested were: 40.0, 40.14, 40.2, 40.4 and 100mm. Their maximum stroke was 200 mm. The friction due to the piston and rod packings was measured by the load-cell sensors mounted on both ends of the rod. The effects of the sliding velocity, rest time and stroke on the friction were tested. Besides, the radial load of the piston packing was measured. The friction was minimized at a sliding velocity and maximized at a stroke. The static friction became remarkably large as the rest time was increased. The radial load was given by the function of the squeeze. The relationship between the friction and the velocity could be normalized by the frictional coefficient and the bearing number.

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The paper presents a theoretical and experimental investigation of sealless pistons with a special profile for reducing friction in pneumatic cylinders. A description of system geometry is followed by the flow rate equations written using a one-dimensional flow model. The axial pressure distribution and the self-centering force on the piston are then determined. The influence of design parameters on system performance is evaluated, and test results are presented for three pistons of the same length and featuring steps of the same height but located in a different axial position. Theoretical results are compared with the experimental data.

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Consistent communications have always been striven for throughout the entire scope of any given automation solution. However, this has only been possible to a limited extent. A possibility which allows for communication with the lowest level, i.e. the sensor and actuator level, has usually been lacking.
The AS interface, recognisable by its characteristic yellow cable, places an “open bus system” for the interconnection of simple, binary sensors and actuators at the disposal of the user which allows for communications all the way down to the sensor and actuator level. The AS interface has firmly established itself within the market with further advantages such as real-time capabilities and reliable data transmission, as well as easy installation thanks to modular design and use of the penetration technique.
Through the use of an applications example, the following paper demonstrates the demands placed on the AS interface by customers, as well as data security measures.

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Thanks to the development of piezoelectric materials able to realize high efficiency vibration generators, it is now possible to develop interface devices between low power electric signals and pneumatic signals, based on the phenomenon of laminar to turbulent transition of air jets. Aim of this work is the study of such kind of devices, particularly oriented to the use of electro-acoustic signals. The paper describes a study carried out on a particular experimental device which allowed to identify the influence of various geometric parameters on the transition effect. A campaign of tests has been completed aimed to a dimensional optimisation of the device. The possible utilisation of the device as interface element for control of pneumatic valves has been considered.

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A new method, which measures the fluctuating sound generated from pneumatic system, was developed. The measuring instrument consists of the sound level meter and the personal computer. The endpoints of time existed the fluctuating sound was accurately determined by applying the algorithm for speech recognition. The equivalent continuous A-weighted sound pressure level between the endpoints was calculated by numerical method.

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A time varying signal may be processed to produce a special identifying code, the variation of which may then be used to both classify and trend faults. This paper describes an extended approach to time signal shape classification, using 4 shape parameters, and the way it may be used to identify any changes in performance, at hourly intervals, of a 4-servovalve Work Roll Bending system on each of the 7 stands of a Hot Steel Strip Rolling Mill. A number of ways of correlating changing plant data are presented and it is seen that the overall approach leads to a satisfactory determination of faults.

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Direct Drive Volume Control Hydraulic Servo System (DDV System) is the system which can control the position of actuator with controlling the revolution of hydraulic pump directly.
This system is known that it can decrease energy consumption because the pump is driven only when the motion of actuator is required. It does not has a transient phenomena such as surging because the change of actuator motion is carried out with changing the direction of pump revolution. It can make the size of system very small, because heat loss of the system is small and it does not require a large size of oil tank for cooling. Many kinds of hydraulic system are used in a ship. One of the most important system is steering system and we adopted the DDV system to “Shioji-maru” which is the training ship of Tokyo Univ. of Mercantile Marine. The results of this study was excellent ; the size of hydraulic source system become less than 1/10, energy consumption become under 1/20 and surging is eliminated.
Considering those results, the authors are trying to apply this system to anti-rolling system with rudder or fin stabilizer.

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A modern hydrostatic transmission for an off-road vehicle must have a high power capacity, a wide speed range and good overall efficiency. A concept that can meet these requirements is one that uses two motors controlled in sequence. The motors are then connected to each other via gearing and are driven at different rotational speeds. To utilise the capacity, one of the motors must be controlled to zero displacement and disconnected at high vehicle speeds. The challenge of the concept is the reconnection procedure, in which the disconnected motor must be accelerated, synchronised and finally locked to the output shaft of the transmission, all in a fraction of a second. In this paper, two principles for establishing the reconnection are investigated in a complete two-motor laboratory test stand. In the first method, the reconnecting motor synchronises using secondary control, in the other it does so by means of a mechanical synchronising mechanism. The aim of the tests is to compare and evaluate different control strategies and hardware configurations.

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The noise of hydraulic power steering system is an unpleasant interior noises of passenger cars. Reduction of structural vibration is one of the effective measures to reduce the noise. At the first step to reduce the structural vibration, the vibration paths and the principal vibration sources should be detected.
In conventional methods for the detection, vibration signals measured at various points are compared with each other. In this method, however, it is difficult to evaluate correlation between measured signals and the principal sources of vibration because those signals generally correlate with each other. Principal component analysis can eliminate the effect of mutual correlation.
In this study, a method to identify principal vibration paths based on principal component analysis was proposed. Also a portable vibration path detector was developed and applied to noise reduction practices of hydraulic power steering system development.

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A study of static flexibility and kinematics of a tripod boom with different kind of joint combinations is presented. In the tripod boom there are parallel modules each of which consists of three hydraulic cylinder, a telescope and triangular plates. The cylinders are connected with the vertices of triangular plates and the telescope is connected with the midpoint of the plate. Different kinds of joints could be used to reach different kind of workspace and appropriate number of degrees of freedom. The parallel modules are spatially connected together. The flexibility of structure is studied and optimized while varying dimensions and positions of boom. Also effects of different kind of joints on the kinematics are studied. AGIFAPanalysis program, which could be used in finite element analysis of beam structures is employed in these studies. A flexibility study through computer simulation, including maximum deformations, is presented.

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This paper deals with virtual HWIL simulation system of a hydraulic excavator using DSP. Hydraulic excavator consists of a complex hydraulic circuits and attachments, which causes the implementation of HWIL simulation system very hard. Hydraulic circuits are realized on DSP and attachments are on main CPUthrough parallel processing algorithms. Through menu the user can set his input parameters for design objectives. Utilizing the datafile of simulation results, the 3D animation can be displayed on graphic monitor. To revival the driver's feeling a joystick has been interfaced with virtual HWIL simulation system as an external input device. The results of virtual HWIL simulation are the same as those of full software simulation and experiments.

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Because of the increased computing capacity, availability of appropriate commercial software and increased knowledge of modelling and simulation of coupled systems, virtual prototyping is becoming a powerful tool in the design of mechatronic machines. When carrying out the design by employing conventional engineering methods the physical couplings between the subsystems such as mechanics, hydraulics and control system are quite often excluded in the design process. 3-D dynamic simulation provides a powerful tool for the designers by means of which the product can be designed in system oriented basis from the early stage of the development. The present paper shows the potential of this approach in designing complete hydraulic driven machines such as log forwarders.

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A modern mobile valve is a complex entity which consist of several integrated valve functions such as pressure compensation, pump flow sharing (anti-saturation), pressure relief and anticavitation. Main spool is either electrically or hydraulically pilot operated with load sensing ability so the valve can be used with LS-pumps.
In this paper the methods of modelling multifunctional mobile valves are presented. The proposed modelling technique is numerically efficient since small internal oil volumes of the valve can be ignored and mathematical stiffness of the model is significantly decreased. The usability of the model is taken into account by means of easy parameterization. The model can be identified using data available in the manufacturers' catalogues.

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Thermodynamic aspects of hydraulic systems become increasingly important in compact systems where there is no room for heat exchangers. It is therefore desirable to facilitate temperature predictions at an early stage of the design process. In this paper two competing concepts of electro-hydrostatic actuation for aircraft applications are studied in order to examine the necessity of a heat exchanger. To be able to capture the fluid temperature in the system, thermodynamic analyses of hydraulic components have been conducted. For the modelling of hydraulic machines a comprehensive loss-model has been implemented with the intention of accurately model the machine efficiency over a wide speed and pressure range. With the help of these models the two systems have been simulated in the HOPSAN simulation package. The systems inputs have been actual pilot commands and aerodynamic loads collected from real missions. The simulation results show that depending of the ambient temperature and the mission characteristics the fl uid temperature would vary to a great extend, stating the demands of the fluid.

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If it is recognised these days that simulation plays a central role in the design process, this should go hand-in-hand with methodology. We intend to underline these metholodological aspects by developing the modelling and simulation of a direct injection system known as “Common Rail”. This modelling is developed on the basis of an elementary models' library facilitating the use of a “polymorphic” approach, that allows to analyse both the stucture of the developed models and the parameters influences.

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Our development program fabricated a proportional control valve that exclusively uses water as its working fluid. The valve is equipped with a spool, and the spool is directly driven by a proportional solenoid that is modified for water use. Characteristics of the proportional solenoid are described first in this report while proving its performances similar to those of the conventional oil hydraulics.
Following, structural characteristics of the water hydraulic proportional control valve are discussed. Water, the valve's working fluid, is low in lubricity and viscosity; therefore, hydrostatic bearings that support the spool are installed in the valve. In addition, to stabilize movement of the spool, damping orifices are provided. Particularly, the hydrostatic bearing portion is designed such that it minimizes the total leakage including bearing flow while obtaining load carrying capacity. The constant flow from the hydrostatic bearings prevents water from decaying in the valve. Lastly, the paper introduces experimental results of cylinder positioning controlled by the developed water hydraulic proportional control valve to verify its satisfactory performances as a control valve.

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This paper deals with numerical simulation of a balanced piston type water hydraulic relief valve. A mathematical model for the valve is derived as ordinary differential equations of 1 lth order and the validity of the model is examined by the comparison with experimental results. The simulation results qualitatively agree well with the experimental ones. Then, the model is linearized around a steady operating point. The stability of the system is studied by a root locus method and the effects of various structural parameters on the stability of the system are investigated. As a result, it is clarified that the middle chamber volume influences the stability of the system markedly.

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The use of water as a working fluid in hydraulic circuits is being receiving an increasing attention by both manufacturers and users, due to its environmental characteristics. Although the use of water is neither new nor innovative (more than one hundred years ago it was widely used to transfer power, and many pump and valve manufacturers have commercial product lines for water hydraulics) its introduction in the product line of a manufacturers brings many problems to the attention of the designers, from technology adaptation to material compatibility, from erosion to cavitation.
The purpose of this paper, based on a joint activity by Cemoter, University of Modena, Aron SpA and Cermet, is to show how the use of a combined approach to valve analysis can provide useful information to shorten the time to market of a valve using tap water as working fluid. Starting from an initial reminder of the basic differences between mineral oil and water in hydraulic circuits, the paper shows the results of some CFD computations on a relief valve, to evaluate the qualitative form of the pressure and velocity field, and to assess the influence of the increased turbulence on the field of motion.
In the final part, the results of a comprehensive experimental characterization of the component are presented and considered in view of the indication provided by CFD analysis, both in term of steady state characteristic curves, and dynamic response.

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This paper deals with the influence of electronic elements, especially the saturation of servo-amplifier and the demodulator filter in the feedback loop of the servovalve. Nonlinear numerical analysis and linear approximation theory are applied to calculate the frequency responses and the wave forms of the system variables. The demodulator filter for LVDT results in an increase of gain and a decrease of a phase lag of spool motion. Thus, it can improve the system response under suitable combination of parameters. The saturation of servo-amplifier distorts wave forms of flapper and spool motion, and renders their frequency response worse.

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The paper gives an insight into the wide variety of innovations that make fluid power a competitive drive concept compared to electrical or mechanical solutions. It provides examples how electronic intelligence and the application of field bus technology contribute to this status. New valves are introduced using silicon etched microstructures or piezo drives as electro-mechanical transducers. The paper also deals with environmentally friendly fluids and how components can be improved utilizing modern materials and coatings. It finishes with a chapter about circuits and provides an example of a miniaturized sevo-pneumatic hand and an electro-rheological servo-hydraulic drive.

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A high pressure electro-hydraulic 2 port valve of 6mm in diameter and 0.4mm stroke is developed for a cyclic pressure test of diesel fuel pipes. The valve compensates steady-state flow force and reduces leaks from both valve seat and lands as minimum as possible for controlling 200MPa diesel fuel. This paper describes the valve design, test results of flow force compensation and of relation between leak and Hertzian pressure at the valve seat, leak from the clearlance of land. It is applied to the cyclic pressure test of a pipe of 560mm in length and 1.59mm in bore.

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In the previous paper based on this study, the authors proposed a high-speed ON/OFF digital valve driven by a laminated piezoelectric (PZT) actuator. One drawback of this digital valve was that the PZT actuator could not produce enough displacement in order to actuate the main valve. Additionally, it may be pointed out that the laminated PZT actuator is considerably expensive for general consumer use. In this study, for the purpose of overcoming such drawbacks, an improved type of high-speed digital valve was developed by adopting a bimorph PZT actuator in place of a laminated actuator. The bimorph PZT is cost-effective to produce and can realize a large displacement; the valve will be financially practical and capable of high performance. To actuate the spool valve, a nozzle-and-flapper mechanism was adopted in the proposed valve. The static and dynamic characteristics of the new device were investigated by experiment and digital simulation. As a result, we found that the valve could be driven by frequencies of a PWM carrier wave as high as 200 Hz.

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This paper deals with chaotic oscillations occurring in a direct-acting poppet valve circuit with a long pipeline. The system is liable to be unstable and various kinds of oscillations are induced. In this study, a distributed parameter model with average friction was derived for the system. Then, several complicated oscillations were examined taking the pipeline length as a control parameter by using the method of numerical simulation. It is shown that chaotic oscillations can occur in some ranges of the control parameter in this system.

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To drive a human-friendly mechanical system such as a human collaboration robo and a welfare machine, a soft actuator having a closer affinity with human is required. This paper describes the fundamental concept of a soft actuator and define its exibility by using a mechanical impedance. Next, the applications of McKibbentype rubber actuator to a rehabilitation robot and a power assist robot are discussed. Also two new types of pneumatic soft actuators being developed in our laboratory are introduced, which are a planar type actuator and a rotary type actuator. Using a pneumatic actuator made of rubber material is one of extremely effective approaches to realize a soft actuator. The study integrating both mechanism and control technology is necessary to build up a practical human-friendly actuation system.

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It is a brand new method for setting up the intelligent system in the paper, which aimed at the improvement of intelligent technolog yatpresent. It is named humachine intelligent system (HIS). In the paper, the authors discuss the architecture of humochino intelligent system, and put forward three kinds of humachine cooperation methods such as “Human Master/Machine Slave (HM/MS)”, “Machine Master/Human Slave (MM/HM)” and “Human Machine Collaboration (IIMC)” to accomplish the humachine intelligence. Automobilism is a very complicated manipulation, in oodcr to improve the automobilism security. The authors put forward an intelligentdriving method based on the idea of humachine system and carry out the simulation experimentation by an automobilesimulator., which indicates that the humuchine intelligent system has prodigious feasibility and superiority.

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One major difficulty in nursing the bedridden is moving their body. This includes lifting and carrying them from one place to another, as well as changing their body posture. Because they are lifting a heavy solid weight while in an unstable posture, the caregiver usually suffers hack pain due to this work. We propose a solution by replacing this labor with robotics technology to lift and/or carry a person. The robot is designed with the smooth, high torque hydraulic actuation, and the bilateral servo system for the control to meet the necessity of the service. The superiority of this robotic device is in its interface and output torque. The bilateral servo system allows the robot to he directly operated (holding the end of the arm) and to control an average weight of a Japanese adult (e.g. 60 kgf) with little effort (e.g. 1 kgf).

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Powerful rescue manipulators are needed to rescue the victims from collapsed houses when earthquake happened. In this paper a new kind of 4 Degrees-of-Freedom (4DOF) redundant hydraulic manipulator is proposed which is expected to be human-cooperative and to execute tasks of manipulating heavy loads, assisting the human power. It consists of large size 2DOFs and small size 2DOFs. Because the large size 2DOFs is massive, the driving system is not designed for fine movements while on the other hand it is suitable for large ones. Only the small size 2DOFs is employed to carry out the fine power-assist tasks. This paper is focused on the design of the controller. First a motion control scheme in conjunction with virtual impedance model is applied to the proposed hydraulic power-assist system. Then a force control method is exploited. Filially a hybrid control scheme using the force control and the motion control alternately is conducted in one working task. The novel hydraulic manipulator is further discussed through some experiments.

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A new control technique is proposed to realize accurate acceleration tracking for repetitive desired acceleration waveforms in an electrohydraulic vibration testing machine. In the proposed algorithm for iterative waveform reformation, the control signal sequence for next operation is determined by utilizing the information of the frequency-response function of the servo mechanism as well as the tracking error obtained from the past operations. It is theoretically clarified first that the stability limit of the iterative reforming process and the convergence speed of the tracking error are predominantly decided by the estimation accuracy of the frequency-response function. Experiments show that nearly perfect tracking can be achieved by using the proposed technique for iterative waveform reformation utilizing the adaptively estimated information of the frequency-response function regardless of kinds of desired waveforms even under operating conditions subjected to inherent highly nonlinearities.

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In accordance with a kind of discrete-time system, the character of the parameter disturbance of the system is studied and a new concept named unchangeablility of the parameter disturbance is put forward for estimating the range of the disturbance. Then, the concept is used in the discrete-time variable structure control for eliminating the range of the sliding mode region. Thus compared with the traditional VSC, the chatter of the system on sliding surface is decreased, the precise of the system output is raised.

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Most vehicles equipped with automatic transmissions use torque converter clutches to reduce the fuel consumption, and recently its slip control scheme is studied for the expansion of the operating region of the torque converter clutch and thus for the further improvement of the fuel economy of vehicles. In this article, the analysis of the torque converter clutch system including the line pressure control unit of the automatic transmission and the actuating hydraulic control unit of the torque converter clutch is performed, and a feedback controller for its slip control is designed. The performance of the designed slip controller is verified by simulations and experiments, and the effect of the torque converter clutch slip control on the fuel economy is examined using a driving cycle simulation.

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In recent years, the hydraulic system of the automatic transmission of a passenger car is becoming more simplified and light-weighted by virtue of the development of the technology of the electronic control and the actuator. Nevertheless, it shows improved shift quality. Following this trend, we design a clutch direct-drive circuit (CDDC) which have one proportional solenoid valve for one clutch, which controls each clutch during shifting. For the analysis of this proportional solenoid valve, we divide this valve into two subsystem: an electrical subsystem and a hydraulic subsystem. Each subsystem is modeled in detail and we verify the reliability of this detailed model through experiments. It turns out that this valve is able to control a clutch pressure precisely enough to obtain good shift quality. For a shift control, we design a control algorithm and are confirmed that the performance of the transient torque reduction is good enough through the feedback shift control experiment at the automatic transmission dynamo which has a hydraulic system using a CDDC.

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This paper proposes an alternative direct teaching and learning method of human skillful tasks for a hydraulic robot manipulator, which realizes the compatibility between the high power performance of hydraulic actuators and the fl exibility of the direct teaching system and is useful to replace the human skill with an appropriate robot controller. The proposed skill teaching process consists of two phases; the direct teaching phase and the off-line learning phase with a neural network applied to learn the skill. In the direct teaching phase, a human operator manipulates an impedancecontrolled robot directly and executes a task to obtain the training data. In the off-line learning phase, a neural network is trained to learn a control strategy included in human tasks. Then, the operator executes the task again in cooperation with a trained neural controller and learning processes are repeated alternately. After several learning processes a neural network is re-trained and the task performance of the controller is improved. The proposed approach is experimentally applied for a control problem of an inverted pendulum by using a 2-link hydraulic manipulator to show the validity of the system. The robustness of neural network controllers trained in different ways is also investigated.

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Our paper describes a new type actuator composed of a pair of two bourdon tubes stnicture basically. The two bourdon tubes drove oscillatory motion antagonistically. The control system of a BTA (Bourdon Tubes Actuator) is positioning and force control.A 13TA is changed from pressure gauge to angle movement, and detected by resolvers attached to each axis. BTA making use of pneumatically had a function of actuator by using Ar. gas or CO₂ gas. Especially 0.05 degree/pulse of positioning repeatability was realized by 13TA only and 0.2mm (Full scale 8mm for each axis) was obtained by the robot. As an application of a BTA, we established a Bio-robotics of pneumatic actuation with 3DOF. This paper is followed from JHPS' 1996, and reports for a very small force control and analysis of a BTA.

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