The paper presents significant good Danish experiment results of a developed CDIO-Concept and approach for active and integrated learning in today's engineering education of MSc Degree students, and research results from using IT-Tools for CAE/CAD and dynamic modelling, simulation, analysis, and design of mechatronics solutions with fluid power actuators for motion control of machines and robots. The idea of CDIO-Concept is to take care of that the students are learning by doing and learning while doing when the students are active to generate new products and solutions by going through the phases from to Conceive, Design, Implement and Operate related to en product design by them self in competition withothers. The idea is based on the Danish implementation of a CDIO-Concept. A curriculum at Aalborg University, andTechnical University of Denmark, offers courses for Motion Control, Fluid Power within mechatronics design, and advantages as well as challenges are identified and discussed. An IT-tool concept for modelling, simulation and design of mechatronic products and systems is proposed, and results from a Danish mechatronic research program on intelligent motion control.

View full abstract

The active utilization of the pressure rise phenomenon of an oil hammer and a new type of hydraulic pressure intensifier using an oil hammer were proposed and developed. In this research, an application of this intensifier to pressure intensification in a hydraulic cylinder of a construction machine is studied through experimentation and simulation.
High pressure is generated when the fluid flow through the pipeline is shut quickly by the solenoid operated valve at the downstream end. If the fluid is taken out through the check valve when the pressure is high, much higher-pressure fluid than the supply is obtained. A vessel is used as a model of a hydraulic cylinder without displacement. The pressure of the vessel is intensified. The necessary pressure level is thought to be around 3 OMPa. We develop a block diagram for the simulation considering the pipeline dynamics.

View full abstract

Recently, excavator is used for not only civil engineering but also building demolition, scrap recycling and so on. The reason is thought that it has a general-purpose power supply system and is able to move by itself. In other words, it could be considered a kind of high-powered robot. As a whole, it consists of several modules. Divided roughly by each function, power module such as an engine and pumps, working module such as front structures and hydraulic actuators, traveling module such as crawlers or wheels, operation module such as control levers and pedals. In this time, to gather and carry lots of objectives in scrap yard or somewhere, both a fork grapple and a loader bucket are equipped as a working module. And to carry the objectives quickly to destination, wheeled traveling system is equipped. As a result, we have produced a multi-functional handling machine which has double front attachments and wheels. Then if operators cooperate the modules effectively, they will be able to handle their work more efficiently.

View full abstract

This paper presents an electromagnetic mmiature pump using peristaltic motion or an intercnangeabe nexlnie woe. Four hinge-type electromagnetic actuators arranged serially in one line pinch a flexible tube and generate peristaltic motion on the tube. In order to reduce electric power consumption, the magnetic latch mechanism using permanent magnets is applied to the actuator drive. As the actuator pinches the outside wall of the interchangeable tube, this pump can deal with any liquids inside the tube. The prototype pump has the flow rate range of 0.1-1cm³/min and the maximum pressure of 13kPa by a battery drive. This paper shows the electromagnetic design of the actuator using the FEM magnetic field analysis. The optimum drive sequence of the pinching actuators and the experimental result of pump characteristics are reported. Furthermore, feasibility consideration of application to the portable intravenous drip system for medical treatments is carried out.

View full abstract

In this paper we propose a delivery method for a PZT jet pump driven by repeated impulsive force of the actuator. The pump is simple in construction being composed of only a piston-cylinder and a receiving hole, and it has no check valves. The multilayer PZT actuator pushes the piston impulsively and the fluid in the cylinder is ejected out through the nozzle forming a jet flow. The receiving hole that is placed facing the nozzle catches the jet flow and one way flow can be obtained. Experimental works indicated that the driving frequency as well as the dimensions such as the diameters of the nozzle and receiving hole was important to improve the pump performance. Moreover it was recognized that while air bubbles were apt to be generated in the cylinder during the suction stroke they were exhausted out of the cylinder at under a certain driving frequency.

View full abstract

A resin-made-bellows pump is used practically as a chemical pump application. Its discharge pressure is low as 0.1MPa in general; therefore, its applicable fields are limited. In order to make the pressure higher, we developed a metal bellows pump driven by an electromagnetic reciprocating actuator for various industrial applications with the pressure of over IOMPa and non-leakage performance. As the pressure becomes higher, larger output force is required to the actuator. The developed electromagnetic actuator can drive the bellows by reciprocating motion in the stroke of 1mm with the maximum output force of 1400N. However, the high-speed motion of the actuator by the armature positionand velocity-sensorless control makes issue that the armature collides hard with the stator and generates the noise and vibration. In this paper, the motion control method to reduce the mechanical collision in the actuator without positionand velocity-sensors is presented.

View full abstract

Due to the high cutting speeds and depths of modern milling machines vibrations are generated within the whole machine structure. These vibrations lead to a poor machined surface and an additional load for all machine components. Within the collaborative research centre 368 “Autonomous Production Cells”, IFAS is involved in the development of an active spindle bearing unit which is capable of damping vibration without reducing milling efficiency [7].
The special layout of the “three cavity ring” results in a high dynamic and stiffness, little need for space and a possible displacement of five tenth of a millimetre. A zero-leakage design is very important for the performance of the actuator. Reducing the leakage of the actuator will increase the dynamic and stiffness of the drive.
Using a micro controller for controlling the bearing unit leads to a decentralised system with local intelligence, that can be integrated into a milling machine.

View full abstract

A hydraulic breaker for construction machinery generally used for the destroying and disassembling of buildings, crashing road pavement, breaking rocks at quarry and so on. So the measurement of the impact energy of a hydraulic breaker is very important thing to prove its capability to manufacturers and customers. In this study, the test system for measuring the impact energy of a hydraulic breaker was designed and constructed. The test system was consisted with hydraulic cylinders for mounting a breaker, impact absorbing base and frames, pressure and flow sensors, high speed and accurate data acquisition system, diesel engine driven hydraulic power pack and etc. The test process of the developed system was carried by measuring guide for tool energy rating for hydraulic breakers which was developed by the CIMA (Construction Industry Manufacturers Association) USA. The developed test system can be applied to measure the impact energy for various kind of hydraulic breakers.

View full abstract

The bench test machine of single shaft is used to develop the motorcycle frame now. It is not expressible for the simple apparatus though combined load is added to the frame while the motorcycle is actually running. Parts of the motorcycle might break down some time. 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.

View full abstract

Recently, aluminum pipe is needed by industrial world. Because it is high rigidity and light. There are many methods of processing pipe. But now bending method is ill-suited to high-mix low-volume production. And so we looked at the feed pressure (MOS) bending machines. But there are many problems in them. First of all, structure of processing part is complex, and object of bending is confirmed to circular pipe. We developed three dimensional pipe bending machine using PKM (parallel kinematics mechanism). In this paper, we will be able to show bending accuracy and proposalof new bending machine.

View full abstract

This communication deals with the thermal-hydraulic modeling and simulation of electrohydraulic actuators to predict the performance sensitivity to temperature. The work reported focuses on the simulation of the servovalve second stage within the AMESim software environment. In the first part, the influence of the static characteristic of this stage on the actuator performance is pointed up. Then, two different models are developed. The fist one is isothermal while the second one considers that all the heat generated by pressure losses is passed to the fluid. The analysis of simulated leakage flow, flow gain and pressure gain displays the influence of temperature and the importance of the type of model. Some extensions of the presented model are proposed to include in detail the heat exchange with ambiance in upcoming work.

View full abstract

In the article the dynamic processes in an axial-reciprocating hydraulic pump and asynchronous engine are considered. The mathematical model of an axial-reciprocating hydraulic pump is presented, where the flow of fluid in each cylinder of the pump and the interaction of liquid with the piston are taken into account. The flow of fluid in a hydraulic system is described by a system of equations of a hyperbolic type, which is solved by the characteristics method. For example, the mathematical simulation of the activity of an axial-reciprocating pump in a hydraulic system together with the mechanical drive is shown.

View full abstract

Accurate predictions of pressure surges are crucial in many fluid-line systems. There are several techniques available for modelling flow transients in hydraulic pipelines, offering different advantages and disadvantages and therefore suiting different applications. In this paper four modelling methods are evaluated in terms of accuracy, computational efficiency and flexibility for laminar, single-phase flow in circular, rigid pipes. These are the method of characteristics (MOC), the finite element method (FEM), the transmission line method (TLM), and the rational polynomial transfer function approximation (RPTFA) method, which is a form of modal approximation method. All four methods were implemented in MATLAB/Simulink. It was found that the RPTFA model potentially gives the most accurate solution, while the MOC and TLM models are the most computationally efficient. The FEM is the least accurate out of the four methods, but it can be used with varying parameters and time steps thus providing the most modelling flexibility.

View full abstract

In this study, hydraulic vibration controller was proposed and tentatively manufactured. Adaptive control method was tried in this experiment for vibration reduction. Proposed vibration absorber is composed of bellows, actuator and accumulator. The device is filled with oil. For input vibration, the actuator is controlled so as to make bellows inside pressure zero. Thus vibration transmission is aimed to reduce. In time, adaptive control method which is able to track non-stationary vibration phenomena is applied.

View full abstract

Hydraulic excavators have been popular devices in construction field because of its multi-workings and economic efficiency. The mathematical models of excavators have many nonlinearities because of nonlinear opening characteristics and dead zone of main control valve, oil temperature variation, etc. The objective of this paper is to develop a simulator for hydraulic excavator using AMESim. Components and whole circuit are expressed graphically. Parameters and nonlinear characteristics are inputted in text style. The simulator can be used to forecast excavator behavior when new components, new mechanical attachments, hydraulic circuit changes, and new control algorithm are applied. The simulator could be a kind of development platform for various new excavators.

View full abstract

The hydraulic automatic gauge control (HAGC) system is the core of the automatic gauge control system in a high speed strip mill. A ripple of the servo valve power supply may affect the performances of HAGC. From the characteristics of the servo valve power supply for a HAGC system, the static relationships of the accumulator's parameters and the power supply, which equips pressure compensated variable displacement pump, are analyzed. By the power supply system modeling and simulation, with the help of the software EASYS, the useful results have been obtained as follow: 1. the relationship of the rate of pressure ripple and the accumulator; 2. the adequate volume of an accumulator; 3. the oil pipe's parameters and the optimal position of an accumulator; 4. the diminution of the load effect in actuator.

View full abstract

Recently an oil-hydraulic system has been compact and high-pressurized and that causes the steep rise of the system temperature because of the small heat volume. When the system temperature has risen so much, characteristics of the working oil deteriorate and the system will be dangerous fmally.
It is very important to study a simple and precise way to predict the temperature rise of the system. The lost power rises the system temperature. Bondgraph method is convenient to predict power loss because the method is based on the concept of power transmission. Consequently, the Bondgraph method is very available to predict the system temperature rise of oil-hydraulic systems.
The oil-flow dynamics with the heat generation mechanism was modeled one-dimensionally using ordinary differential equations by Bondgraph method, which is very convenient for modeling and simulation of heat generation. On the other hand, the heat transfer in the housing was analyzed three-dimensionally using the partial differential equation of heat conduction. The prediction of the temperature distributions were calculated effectively by coupling these two kinds of equation systems. In the present paper, this prediction method is applied to a real oil-hydraulic system. The simulation result was compared with the experimental results and they agreed very well.

View full abstract

This study is an experimental investigation on porous media in feeding system of aerostatic bearings. The experiments were conducted using sintered bronze cylindrical inserts of different length, diameter and particle size. The work outlines two types of experiments namely: a) the measurement of mass flow rate through single porous resistance with different upstream and downstream pressures; b) the study of pressure distribution, on a pneumatic pad featuring porous resistance feeding system. The set-up used for the former included the device under test, a flow regulator and pressure transducers. For the latter the set-up included the pad under test and a stationary bearing member under the pad to evaluate pressure distribution by means of a pressure transducer.
The immediate objective of the work is to define a fluid porous resistance to be provided on the pad, equivalent to that of a 0.25 mm calibrated orifice already applied to a similar pad.

View full abstract

A high performance pneumatic silencer to reduce unpleasantness of the noise is newly developed in this paper. It is shown that a sound effect of fade-in found by consideration of results from ergonomics is obtained by the silencer. The silencer consists of three kinds of silencers and a device. The device uses artificial muscle utilized a shape memory alloy. It is cleared that sound power level of the silencer is very low.

View full abstract

We developed the control system having opto-fluid converter.
This system is composed by opto-fluid converter, 4 stage cascades of Laminar Proportional Amplifier (LPA) which amplify the pressure difference from optical-fluid converter, and the pneumatic servo valve which sends the actual working air pressure to an actuator of a robot arm. By isolating an electric signal processing part and an optical signal processing part using the optical fiber, the control system which is not influenced by an electromagnetic noise can been realized. The optical signal is changed into the fluid pressure signal, without an intermediary electric signal, and can control the robot arm. The system can work under the severe environment where the radioactivity or an electromagnetic noise influences it, and an activity can be expected at medical spots, a nuclear reactor, etc. In this report, we have an analyzed the characteristics of the opto-fluid converter in order to design the high-speed response and optimize the converter.

View full abstract

This report treats a development of an opto-fluidic conversion device. Using a bundled optical fiber which has the sectional area of 1.0 [mm]×5.0 [mm], 2.0 [mm]×5.0 [mm] and 3.0 [mm]×5.0 [mm] respectively, the dynamic characteristics on an opto-fluidic conversion device have been analyzed. This paper reports analysis result of the dynamic characteristics and the effect on the size of the optimal sectional area of the bundled optical fiber. From the analytical result of the dynamic characteristics, it has been confirmed that the bundled optical fiber with the sectional area of 2.0 [mm]×5.0 [mm] has been optimal in the test case.

View full abstract

Mines installed into sea are a serious threat to navigation during wars or other un-certain conditions. During years mines have become quite sophisticated. Every ship passing through the water emits sound, disturbs the Earth's magnetic field, and causes fluctuations in water pressure. Mine clearing is important and challenging task. Sea mines react to stimulus of ships. Noise caused by ships is one of remarkable stimulus. Mines reacting to noise are tried to clear with acoustic mine clearing equipment. In order to image noise generated by different ships quite large frequency range is required. High frequencies (>100 Hz) can be achieved, for instance, with permanent magnet and magnetostrictive hydro-sounders. At low frequencies (≤60Hz) hydraulic hydro-sounder might be a reasonable solution. In this paper the preliminary design, modeling and experimental tests of hydraulic cylinder driven hydro-sounder are presented.

View full abstract

In teleoperation applications torque controlled joints are often required. If hydraulic actuator is driven by flow control servovalve, a force-based position control requires tuning of inner loop force controller and force or pressure sensor. An alternative for flow control servovalves are pressure servovalves which are seldom used in industrial applications. Advantage of this technology should be that tuning of inner force-control loop should be avoided and also more importantly addition of pressure and/or force feedback sensors should not required. Sensors are often the most likely component to fail while working in hazardous environments. Our aim is to compare three kinds of inner loop force controls. First, we use pressure servovalve in position control application without inner loop pressure or force sensors. In remaining two cases we use force control in the inner control loop with flow and pressure control servovalve. Three controller alternatives are compared and the results are discussed.

View full abstract

This paper develops a design of adaptive pressure controller for hydraulic servo valve with unknown dead zone. In general to reduce leakage flow, the servo valves adopt positive lap structures. This makes dead zone larger and is obstacle for precise positioning control. To compensate of such dead zone and unknown physical parameters of system, adaptive control strategy is examined for simple pressure control system. First it is assumed that only the flow gain of servo valve can be known by experiment and the adaptive controller is designed. This controller is examined on water hydraulic servo system which has larger leakage and positive lap for lower viscosity of tap water. The experimental results show that the better tracking performance is obtained comparing with PI or conventional adaptive controller without dead zone compensation. Then the controller is extended for unknown flow gain case.

View full abstract

Generally most hydraulic systems are intrensically non-linear, why applying linearcontrol techniques typically results in conservatively dimensioned controllers to obtain stable performance. Non-linear control techniques have the potential of overcoming these problems, and in this paper the focus is on developing and applying several different feedback linearisation (FL) controllers to the individual servo actuators in a hydraulically driven servo robot to evaluate and compare their possiblities and limitations. This is done based on both simulation and experimental results.

View full abstract

The problem of control of force exerted by pneumatic cylinders on the environment is of interest in industrial automation and systems such as legged robots. In this paper, a sliding mode fuzzy force control algorithm is proposed for pneumatic cylinders. The environment is assumed to be “soft” or compliant and modeled as a spring. The advantage of the new controller is that being based on fuzzy logic, knowledge of the cylinder dynamics or disturbances such as friction is not necessary. The control law implementation is based explicitly on contact force measurements. The proposed algorithm is simple, robust, and easy to implement. Results of experimental implementation are presented to illustrate the practical effectiveness of the new method.

View full abstract

A power-assisted chair using pneumatic system has been studied by the authors. The chair aims to help the user to stand up with assistance force generated by a pneumatic cylinder. In this study, a pneumatic cylinder, control valves, a compressor, a microcomputer and electric power sources are integrated in the chair. Control and measurement techniques using the microcomputer are described in this paper.

View full abstract

A pneumatic artificial muscle actuator (PAM actuator), has been regarded during the recent decades as an interesting alternative to hydraulic and electric actuators because of these advantages such as high power to weight ratio, low cost, readily available and cheap power source, inherent safety and mobility assistance to humans performing tasks. However, problems with the air compressibility and the lack of damping ability have made it difficult to realize motion with high accuracy, high speed and with respect to various external inertia loads in order to realize a human-friendly therapy robot (HFTR).
An intelligent phase plane switching controller, which harmonizes a phase plane switching control (PPSC) algorithm, conventional PID controller and the adaptabilities of neural network, is newly proposed in this study. In order to realize satisfactory control performance, Magneto-Rheological Brake (MRB) is equipped to the joint of the manipulator. The experiments were carried out in practical PAM manipulator and the effectiveness of the newly proposed control algorithm was demonstrated through experiments, which proved that the stability of the manipulator could be improved greatly in a high gain control without regard to the change of external inertia loads.

View full abstract

In care activity or rescue activity, hands that can grasp creatures are sometimes needed. Therefore, it is considered that the soft mechanism that uses pneumatic elements is useful to realize such hands. In this paper, we propose a new type of soft actuator (Sponge-Core-Soft Rubber Actuator) in which a sponge rubber is covered with silicon rubber. The structure of the sponge rubber is divided into two types. One is single-layer type and the other is two-layer type (a flat type and a clipping type). In order to clarify the differences in characteristics of each actuator, we examine the basic characteristics of the actuators. Further, the control performances of both position and force are studied to realize a hybrid element. From some experimental results, the control performance of the two layers type actuator is illustrated.

View full abstract

Recently, virtual reality systems that feed back to human senses have only been realized as visual and acoustic feedback. However, they are not enough to realize the force feedback system for hands, arms, legs and so on. The actuators required for such a system need to be flexible so as not to injure the body. The purpose of our study is to develop a flexible and lightweight actuator which can be safe enough to be attached to the human body. We propose new types of flexible pneumatic actuator that can be used even if the actuator is deformed by external force. In this study, we tested rodless type flexible pneumatic cylinders that have a self holding function for positioning under the condition of no supply pressure. We also developed a new type of McKibben artificial muscle that has a long stroke of more than 80% of its original length. As a result of our experiment, we can confirm that the tested cylinder is useful to be applied in a positioning system because it consumes less air under the condition of holding. By using the tested Mckibben actuator, we can realize a long stroke lifting motion of a dumbbell whose mass is 6kg.

View full abstract

In order to realize an assist of independent life for people in need of care and relieve a physical burden for care worker, an active support splint driven by pneumatic soft actuator (ASSIST) to support a human arm has been developed. ASSIST is constructed with the appliance and the rotary-type soft actuator. Since a weight and hardness of device involve a danger of causing a serious accident for users or neighbors, this device is constructed with components which are a lightweight and have a mechanical softness. In this paper, the structure of developed device is described, and then the control method based on the center of pressure is proposed. Finally, the assist effectiveness using the proposed control method is experimentally discussed.

View full abstract

The main objective of this research is to demonstrate experimentally the feasibility of teleoperating a hydraulic system over Internet in real tilne. The teleoperation is based on the client/server architecture. Time delay caused by Internet is the main problem of the teleoperation system. After discussing the characteristic of uncertain time delay and the format of communication protocol, this paper introduces a control algorithm with prediction. Combining with the characteristic of time delay and TCP/IP protocol, this method can compensate the time delay existing in forward and feedback path. Moreover, the operator can operate transparently the master just as operating the remote object. A hydraulic master slave system is developed as a test rig and experimental results verify the feasibility of the compensator.

View full abstract

At present, biped robots are designed having motors on each joint. But human have actuators that span two joints, and the antagonistic pair actuator drives two joints at the same time. In these days, the effects of this study that is source of fast motor such as jump or running are investigated on Body moment study and Biology. This study shows the basic principle and the driving mechanism of the new actuator, called bilateral servo system developed in our laboratory, having the bi-articular operation to adjust a biped robot, and characteristics of the actuator that driving joint. As for those characteristics, this paper expresses the bilateral servo system and the robot that use the actuators.

View full abstract

Nowadays, the breast cancer, over ahead of stomach one, holds the highest cancer incidence rate among Japanese women. Detection of breast cancer is done by palpation diagnosis, which require doctor to have highly experienced technique. In this study, we develop a palpation simulator which forms a woman's actual breast model holding active controlled variable stiffness property. A pneumatic parallel manipulator is employed as mechanical part of our simulator. In order to display a concrete stiffness feeling to human (doctor), control strategy is proposed where the contact point is detected using an idea of graphical intersection test. A reference stiffness is realized by constructing a compliance control system. By regulating the reference stiffness value according to the contact point, a palpation motion is executed. The validity of the proposed palpation system are confirmed through some experiments and analysis.

View full abstract

In this research, we selected Pneumatic Bilateral Servo System (PBSS) consisting of master and slave cylinders as an actuator system for the land mine apparatus. Usually the master side operates the slave side in PBSS. But we realized in our system that position and power controls are made by comparing and feeding back physical information between the master and the slave. It also makes possible that the slave operates the master on the basis of this information. For the above reasons, PBSS is suited to be the actuator for the land mines apparatus. In this research, we work on the following tasks based on PBSS as the basic system.(1) Construction of pneumatically-controlled bilateral servo system (2) This system becomes harmless on the environment and human.(3) Making this system can sense and be controlled by minute pressure change by the 100-grain weight.

View full abstract

For energy saving, many attempts were tried in off-highway, highway vehicle and tram.First, we studied SATV vehicle of breakthrough and rescue purpose which is composed of hybrid power line CPS for low speed and MMT for high speed running.
Second, we studied CPS vehicle composed of variable P/M and energy recovery of flywheel.
In the last, we introduced flywheel driven FST tram prototype performance recently developed. This system is controlled by switching valve using fixed P/M.

View full abstract

Recently, a technology on the machines under computer control is become established. However huge working power of the hydraulic mechanics is difficult to control with taking efficient power transmission and its precision. Then hydraulic switching power control system is contrived based on analogy between electric circuit and fluid circuit. Hydraulic and electric switching devices are called valves as both circuits on nomenclature. The hydraulic switching control on huge working power have been disclose only a few years ago, at first in the world on JFPS Spring Meeting on Fluid Power, May 2002 in Japan. This paper is described process of some experiment to have evidence to practical use of the Hydraulic Switching Control. We have obtained patents about the hydraulic switching control as a new theory on the Fluid Power Systems, and registered it as the trade mark “FST” means Fluid Switching Transmission. Outline of the performance of the FST is also described in this paper.

View full abstract

Marine Diesel engines are converting their fundamental futures, they are compelled to suppress the emissions of CO₂, NO_X, and others maintaining the conference around the thin layer of the earth surface, then these engines are beginning to convert their design concept now. However, it seamed for us that is processing by poor technology and concept, such as the applying computers and electric controls only. The principal reforms of the engines are remove their camshaft, tappets, mechanical push rods, rocker arms and mechanical injection pumps and the tasks are depend to computer and electric control. The engines applied the new concept has some small advantage to traditional engines, easy start and reverse, etc, but facing serious difficulties of its reducing thermal efficiency. This paper describes that the compatibility of suppress the emissions keeping high thermal efficiency of the engine. We are remaking an engine will be changed from conventional engine to the innovative one applying our patent HYDRAULIC SWITCHING TECHNOROGY.

View full abstract

A new generation of cleaning robots for domotic applications based on all-pneumatic technology is on study; the project deals with three main fields: motion, cleaning and drying. Referring to motion, an innovative design using pneumatic cylinders as structural elements is being tested; the implementation of a control made with digital valves permits to reduce costs, decrease setup times and leads to a unit which can be easily reconfigured for various applications. A recently developed series of vacuum cups allows the unit to stick itself on surfaces even if dirty or wet; innovative design and materials were studied to guarantee a firm grip in extreme conditions such as metal or glass covered by lubricating fluids. The structure used for motion system and the solutions for control the unit are shown. The cleaning system is based on pneumatic motor driving of rotating brushes with water injection between them. The drying system is based on fluidic concepts and driven by compressed air; studies about Coanda effect were carried on trying to extract water directly from wet surface without contact. Computational Fluid Dynamic simulations and experimental tests were carried on to validate the models; comparative analysis about performances and fluid consumption are here presented.

View full abstract

A fully electronically controllable valve-actuator has potentials of improving volumetric efficiency at gas exchange, and of presenting variable compression-ratio. This paper describes a new type of hydro-mechanical position-servo electro-hydraulic valve actuator for a cam-less engine. The piston is positioned hydro mechanical feedback mechanism, which balances the flow rate of the feedback slot to the pilot valve. The feedback-slot opens its area in proportion to the piston displacement. This mechanism succeeds to decelerate the landing-velocity of 0.2m/s at a working speed of 1.0m/s for valve lift of 12mm, and to actuate the valve at a volumetric efficiency of 95% within lag times of opening 18ms and closing 8ms, that is possible to work at an equivalent engine rotational speed of 2100rpm. The actuator is energized by the hydraulic power source of flow-rate of 6.7L/min and pressure of 14MPa.

View full abstract

In the study on the braking system, the inertia simulator is necessary, which is generally realized by inertia plate. Its advantage is simple and accurate, whereas the disadvantage is the larger volume and difficult to be adjusted. This paper presents a novel scheme, which is realized by hydrostatic secondary control circuit. The inertia can be increased and decreased by electro-hydraulic servo control through momentum feedback, in which a dual variable servo pump is adopted, with the velocity and torque feedback loops applied. In the beginning, it is set as speed control mode until it reaches the braking speed. Meanwhile, it turns to the sate of inertia simulator, which is the torque control mode, so as to keep the inertia as set value.
The function of inertia simulation system based on hydrostatic secondary control is to simulate the momentum, which is realized by momentum feedback control, and it can be calculated through accelerator and desired inertia. The variable pump is driven by constant pressure network, and the variable swashplate is controlled through servo valve. The torque feedback and speed feedback guarantee the control performance requirements. Since there are some problems of nonlinearity, instability, strength friction, etc. a hybrid fuzzy control method are adopted to get higher dynamic control precise and steady characteristics. It is concluded that the scheme and control method is available and validity.

View full abstract

In the common rail system with direct injection equipment in diesel engine, a proportional metering valve to control the fuel flow into the high pressure pump is used. The proportional solenoid actuator is suitable for metering valve because it has a constant attraction force in the control region independently on the stroke position and a fast motion response of the plunger. The force characteristics with respect to the stroke of the proportional solenoid actuator is strongly depending on the shape of the control cone, but it is difficult to design the control cone. In this paper, a proportional solenoid actuator of electrohydraulic proportional metering valve for common rail system was analyzed using finite element method and the shape of the control cone of the proportional solenoid actuator was optimized to get the constant force in the control region. The analysis results of the optimized proportional solenoid actuator were compared with the experimental results of the manufactured one.

View full abstract

This paper presents a comparison of the energetic consumption of a valveless and a valve controlled active oscillation damping system for off-road machinery. Today only passive oscillation damping systems are subject to off-road machine series production. These systems offer the advantage of no additional primary energy use for damping. However, the disadvantages are the high costs and no adaptation possibility to the operating parameters. The recent developments where valve controlled linear actuators have been used for active damping had to face several problems with too low dynamics of today's implemented control valves and the high additional energy need. These disadvantages can be avoided by using valveless linear actuators for working functions and for active damping. In fact, throttling losses are omitted and, energy recovery is possible. It will be shown based on measurement and simulation results that a suitable damping quality can be achieved with valveless linear actuators. Therefore, some aspects of the controller design will be given. Hereby, a simple acceleration sensor and standard control hardware are used. The main part will describe the energetic modelling, whereby especially precise pump loss models have been developed. The energy consumption of both systems performing active damping is compared in detail.

View full abstract

Performance of a hydraulic piston motor is very difficult to estimate in advance before experiment. But it is highly required because, if an efficiency model for performance estimation is already in hands, the model enables one to design a hydraulic motor with good efficiency at a designated operating point. Recently such a performance estimation model is developed by H.S. Jeong. In this paper, validity and accuracy of the performance model is studied by comparison with experimental efficiency test data.

View full abstract

In mobile hydraulic systems such as commercial vehicles, hydraulic fluids are splashed and agitated in the reservoirs. To overcome air entrainment in oils, the overall dimensions should enclose a sufficient volume of oil to permit air bubbles to escape passively during the resident time of the fluid in the reservoir. However, in view point of enviromnental compatibility, energy saving, cost saving and safety, one trend in fluid power systems is to be designed in a more compact fashion and requiring less fluid in the reservoir. One of the authors has developed a newly device using swirl flow for bubble elimination capable of eliminating bubbles and of decreasing dissolved gases. This device is called the bubble eliminator. In this paper we focus on the technical issue of oil degradation for the air bubbles and oil temperature rise in the reservoir of a test hydraulic circuit. In our experiments, surrounding air is intentionally introduced from the oil surface by vibration of the reservoir in the hydraulic circuit. The bubble eliminator solves many problems concerning the air entrainment in hydraulic systems.

View full abstract

This paper shows the energy saving power steering system, which was named as KEEPS (Kayaba Electronic Controlled Energy Saving Power Steering). In a conventional hydraulic power steering system, the hydraulic pump always supplies enough quantity of oil to the hydraulic circuit. This extra oil flow increases driving torque of the pump, thus the hydraulic power steering system wastes energy. On the other hand, KEEPS can control oil flow electrically in accordance with the condition of a vehicle. In the measurement test for energy consumption of the power steering system with the actual vehicle on test courses, KEEPS got 48% less at city mode, 41% less at highway mode and 39% less at country mode compared with the conventional hydraulic steering system.

View full abstract

In many fields, all terrain vehicles are highly demanded with high performance and efficient energy consumption. Some vehicles run on four or six tires, and some vehicles run rubber tracks, called crawlers. In this paper, we will focus on crawlers and their applications. First, we will describe the vehicle's features, and its characteristics. A unique four-wheel-steering Z link mechanism is applied. Crawlers with a tilting mechanism are applied that enables the vehicle to run over steps and obstacles.

View full abstract

It is well known that wireless technology has been widely used in communication. In recent years it has been ubiquitous in nearly every aspect of industry, medicine, environment and meteorology. The wireless technology will revolutionize these fields. This paper presents a wireless pneumatic system which consists of a controlled wireless pneumatic proportional valve based on SMC VEF-312 and a wireless transducer of flowmeter for monitoring the flowrate. The results about the application of wireless technology in pneumatic system were discussed.

View full abstract

This study is concerned with the development of a novel portable pneumatic power source applicable to self-powered mobile applications such as wearable actuator and rescue robot etc. Dry ice is chosen as a source of power for the pneumatic power source because it is nonpoisonous, easy to obtain and it expands 750 times in volume after being vaporized into gas. When dry ice is stored in the confined pressure container, it begins to liquefy after the pressure reaches the triple point (0.52 [MPa (abs)], -56.6°C). In this process the pressure remains constant until all the dry ice melt into the liquid. When the state remains at triple point, the pressure does not decrease even though the gas is released from pressure container. By using this physical property of carbon dioxide, and by controlling the heat transfer from the surroundings into the pressure container, a noiseless, large capacity and portable pneumatic power source is developed.

View full abstract

This paper presents the first study on how the unbalance of temperature recovery after air charged has a significant effect on the accuracy and repeatability of air leak detection. From this viewpoint, temperature recovery time is derived and affecting parameters are investigated. In a leak detection based on differential pressure measurement, the leak is detected by measuring pressure difference between a reference component, which is leak tight, and a tested component using a differential pressure sensor. When the tested component is leaking, the pressure inside it decreases and the pressure difference with the reference is measured. However, when the required temperature recovery time is not satisfied, unbalance of temperature recovery due to a possibly small difference of heat transfer coefficient between the reference and tested component can produce pressure difference that is similar in size as a real leak and larger uncertainty. This phenomenon is described theoretically and the experimental data are in satisfactory agreement with the calculated results.

View full abstract