This paper describes a method of trajectory planning, parameters adjustment on servo systems and application to vibration reduction on novel press machines using AC servo motors. Recently, the servo presses are spreading over a market because they have advantages of stabilization of processing accuracy, improvement in fabricability of processing materials and large reduction of operation noise. The servo systems with the linkage mechanism sometimes generate impact noise in gears or trajectory fluctuation of the input side due to the nonlinearities. We have developed a simulation approach for motion control of servo presses with linkage mechanism through the vector method. The experiment result and the transient analysis result have good agreement. In this study, it is shown clearly that the cause of the trajectory fluctuation is the interaction of the nonlinearity of linkage mechanism and the discretization of a output side trajectory. The parameter design becomes easy and convenient by using the proposed diagram for the evaluation. The suitable parameter design shortens the cycle time and reduces the vibration of AC servo presses.

抄録全体を表示

In this paper, an estimation method for velocity and acceleration from sampled displacement data using Radial Basis Function (RBF) interpolation is proposed. In some cases such as parameter identification of a robot using sampled signals of joint angle and motion control only with displacement sensor, accuracy of the estimation method for velocity and acceleratation affects the results of identification or control. In proposed estimation method, sampled displacement data are firstly interpolated with RBFs and estimated velocity and acceleration are derived from analytical differenciation of the interpolation. Off-line estimation that can be utilized in off-line parameter identification scheme is discussed. Considering on-line identification of System parameters of robot, quasi-instantaneous estimation method also developed, in which a least five latest measured data are required. Accuracy of the proposed method is evaluated in both the frequency domain and the time domain.

抄録全体を表示

This paper presents a new tactile sensor that can detect the vertical force and the shear force. This proposed tactile sensor detects an applied force as a change in electrical resistance in strain gauges attached to the surface. For outputs of this proposed sensor, the interaction occurs structurally, and the hysteresis also occurs since the force applying on the sensor is detected by the strain gauge attached to the surface. However, since the effects of the hysteresis are small and difficult to correct, we disregard the hysteresis, and only correct the interaction. Measurement of the vertical and shear forces applying on this proposed tactile sensor becomes possible after correcting the interaction. The experimental results show that three dimensional forces can measure using this proposed tactile sensor. This proposed tactile sensor has simple structure. Therefore, because of this structure, this tactile sensor can be made easily and realized as small size.

抄録全体を表示

An ultrasonic dental scaler is an equipment to remove dental calculi from teeth. A conventional scaler consists of handpiece with a Langevin type ultrasonic transducer and a driver circuit to vibrate at resonance frequency. The transducer has a horn to enhance vibration and a tip to scale the calculi. On the back of the transducer, a rubber hose is connected to supply water to the scaling points. Such a transducer has two problems. One is vibration damping due to the water hose. The other is resonance frequency shift according to contact load on the tip. Two types of transducer are fabricated to compare influence of the hose connecting method. Measuring electric Q factor with water flowing, side connection seems to decrease the damping rather than back connection. A new transducer is designed based on the comparison result. To trace the frequency shift, we develop a resonance trace system. Arranging operating frequency based on detected current phase, the system can trace mechanical resonance with time delay of 17 ms. We also propose teeth diagnosis using the resonance trace system. Observing the resonance frequency shift when the tip contacts a material, stiffness of the material can be estimated. The shift comparison result between a damaged tooth and a fine tooth shows possibility of dental caries diagnosis.

抄録全体を表示

The range of applications using microvibration isolation equipment is being extended even to devices for which the influence of vibration was not previously considered. As a representative example, the application of an active microvibration isolation equipment with an air spring actuator, suitable for MRI and NMR that operate in a strong magnetic field, is examined. For use in a strong magnetic field, the active microvibration isolation equipment needs to have an actuator made of a nonmagnetic material. The servo valve that controls air pressure in the actuator, however, must be installed away from the strong magnetic field because it cannot be fabricated from a nonmagnetic material. This necessitates a long air supply tube to connect the servo valve to the actuator. Since this long tube affects the actuator characteristics, adequate vibration isolation performance cannot be attained with a controller designed using the conventional equipment model. In this study, a new equipment model is proposed by analyzing the characteristics of the active microvibration isolation equipment, and the control system is designed for the model using the model matching technique. The equipment model and control technique are validated by simulation and experiments.

抄録全体を表示

This paper shows estimation of mechanical characteristics of rubber bearings with multi lead plugs using finite element analysis. The rubber bearings were the prototypes designed for isolation system for the nuclear power plants. It was required to support vertical stress from 5.0 to 7.5 MPa and keep larger volume of lead than regulated by JEAG guideline for larger damping from the stand point of efficient costs. The effect of number of lead plugs on mechanical characteristics, stress configuration and yielding of steel plates were investigated and compared with a bearings have a lead plug that volume was permitted by JEAG guidelines.

抄録全体を表示

This paper aims to analyze fundamental dynamic characteristics of tilting railway vehicle using variable link mechanism for compensating both lateral acceleration that passengers feel and wheel load imbalance between inner and outer rails. In this report, geometric relations between the center of rotation, the center of gravity, and the positions of all four links of tilting system are analyzed. Then, equations of the pendulum motions of railway vehicle body with four-link mechanism are derived. This paper theoretically discusses about the geometrical shapes of link mechanism that can provide zero lateral acceleration and zero wheel load fluctuation simultaneously. Then, “perfect tilting condition”, which is the control target of feedforward tilting control, is derived by linear equation of tilting motion.

抄録全体を表示

It is important to prevent commuter trains overrunning which are caused by human errors. Although skillful drivers can robustly withstand drastic changes to situations, they may make a mistake. In this paper, we focus on a braking control problem in which the task of the human operator is to make the train stop exactly at a given position. We propose a support system for the human operator, which applies so-called Just-In-Time modeling to predictive control. Moreover, we propose a human-machine interface system which displays the level how far the current manipulation apart from the usual ones by using an input-output database. The effectiveness of the proposed method is demonstrated by simulations of a braking system on trains.

抄録全体を表示

The air suspension system is now widely used for railway vehicles. To improve the riding comfort of vehicles equipped with this system, we tested semi-active control system of air suspensions having a variable orifice which is installed between air spring and auxiliary air chamber, and is controlled by a controller designed based on the H_∞ control algorism. Numerical simulations using 1/2 railway vehicle model with 4 components air suspension model and excitation tests using a 1/2 carbody on rolling stock testing plant are earried out. The results show that the proposed system reduces effectively the power spectral density (PSD) of acceleration of the carbody floor, and there is observed little difference in the effectiveness of vibration mitigation between the case of using a reduced-order controller and the case of using the original one.

抄録全体を表示

In order to improve vertical ride comfort aboard railway vehicles, it has recently become essential to suppress vertical bending vibration of carbody. In many cases, the resonant frequency of the system which consists of bogie frame and axle springs is close to the one of the first mode bending vibration of carbody. Therefore, suppressing the vibration of bogie frames near their resonant frequency effectively reduces the vibration of carbody. In this paper, we propose a method to suppress this vibration by controlling damping force of axle dampers, which are installed between bogie frames and wheel sets. The semi-active controller that is applied to determine the optimal damping force is designed based on the sky-hook control theory. Both numerical simulations using a vehicle model with 16 degrees of freedom and excitation tests using a carbody with variable coefficient axle dampers on rolling stock testing plant are carried out. In results, we show that the control method effectively reduces the power spectral density (PSD) of acceleration on the floor and the ride comfort level (LT) can be improved by about 3 dB.

抄録全体を表示

When large external forces come from road, a suspension stroke reaches the limitation and the riding comfort may reduce. In order to overcome this problem we propose a new control method for an active suspension which can avoid reaching the stroke limitation. A sliding mode controller is designed in consideration of rigidity variation of the spring. Also in order to estimate the internal state of the suspension, VSS (Variable Structural System) observer is designed without information of nonlinear force which occurred in rigidity variation when the suspension reaches the stroke limitation. By carrying out simulation and experiment of a quarter-car suspension model it is verified that the performance of the controller is superior to that of the method, which switches to a passive damper near the stroke limitation from LQR (Linear Quadratic Regulator) in the range of small stroke.

抄録全体を表示

In this paper, flight controller design for the lateral/direction motions of in-flight simulator MuPAL-α is discussed. For the simultaneous simulation of gust responses and pilot input responses of model aircraft, feedback and feedforward controllers are designed in two steps; feedback controllers for robust model-matching problem are first designed using scaled H_∞ control to simulate the gust responses of target aircraft, and then feedforward controllers for H_∞ model-matching are designed as right inverse systems to simulate the aircraft responses driven by pilot inputs. In the feedback controller design, we use airspeed in stead of inertial speed which was used in our previous report. After confirming that designed controllers have good model-matching performance with numerical simulations, we conducted hardware-in-the-loop simulations and flight tests. In the flight tests, we confirmed that controllers with air speed feedback have better model-matching performance than controllers with inertial speed feedback, i.e. we have improved the model-matching performance of in-flight simulator MuPAL-α for its lateral/directional motions.

抄録全体を表示

In this paper, we design a trajectory following controller by using model following based sliding mode control for small-scale unmanned helicopter. Firstly, we derive reference model that shows an ideal response. This reference model follows continuous trajectory like a circular trajectory without delay. Secondly, we design the model following based sliding mode controller that makes the response of real system follow the response of reference model. Lastly, we show the validity of the controller by the simulation and experiment.

抄録全体を表示

In this paper, we discuss an aerial posture control problem of a 3-link horizontal bar robot with nonzero initial angular momentum. Two joints of the robot can be controlled under the in-phase or out-of-phase constraint. We alrady succeeded in realizing 3-link aerial robot control under the in-phase constraint by using anglular velocity in our previous study. In this paper, we show a way to control the robot under the in-phase and out-of-phase constraint by using torque input. First, the law of conservation of angular momentum is shown and an error equation is derived for a 3-link aerial robot. Next, the necessary condition which assures the existence of the control low under the out-of-phase constraint is derived. A feedback control law is derived by the backstepping technique which guarantees Lyapunov stability of the error system. The feedback control input is calculated numerically by solving a fourth order equation. The problem of un-uniquencess of the solution is avoided by a simple condition. Finally, simulation results are presented to show validity of the proposed control strategy.

抄録全体を表示

This paper discusses a control method of the giant swing motion of a 3-DOF link horizontal bar mechanism that is controlled by a discrete-time controller. The stability of a periodic motion that is controlled by a discrete-time controller is firstly defined. Secondly, in order to increase stability of the giant swing motion of a 3 DOF link horizontal bar mechanism, a control technique that is named the discrete-time variable gain configuration control is proposed. Moreover, an acceleration control method that accelerates swing motion of the mechanism to a certain free giant swing motion is derived. Experimental result proves an effectiveness of our control methods.

抄録全体を表示

In this paper, a linear robust control system design based on μ-synthesis is proposed for impedance shaped 2-DOF robot manipulators in bilateral master-slave robotic system with environmental uncertainties and communication delay. A general condition based on the structured singular value μ for robustness of a bilateral master-slave robotic system is derived. The proposed control methodology can guarantee the robust stability and the robust performance for environmental uncertainty, perturbation of operator dynamics, perturbation of master and slave robot manipulator dynamics and constant communication delay of the master-slave robotic system. Several experimental results show the effectiveness of our proposed approach for various environmental uncertainties and constant communication delay.

抄録全体を表示

The mine detection hexapod robot COMET-III is driven by hydraulic power. It is necessary for walking robot to achieve a high trajectory tracking performance. But because of the strong nonlinear characteristic of the hydraulic system, conventional classical control methods generate the delay to the reference trajectory. The sliding mode control has strong robustness to parameter change or disturbance, and the model following control follows the dynamic characteristics of plant to a reference model as an ideal characteristics. Then, the response of the system is improved by means of a feedback effect with disturbance observer in the inner loop. So we design a reference model following sliding mode controller, which combines the advantages of these control theory. In this paper, it is shown that our control method can improve the trajectory tracking performance and robustness of the system through experiments and simulations.

抄録全体を表示

This paper presents a nonlinear controller for electric power assist systems based on the sliding mode control. The proposed sliding mode controller is designed to achieve desired nonlinear properties including gravitational effect with robustness against disturbances such as friction force and modeling errors. Furthermore, so-called reaching phase is positively utilized so that the operator can feel disturbance torque of relatively large amplitude which should be noticed as information about environment, for example, when hitting an obstacle accidentally. Since the reaching phase should be designed from several points of view, the dynamics in the reaching phase is linearlized in order to use fruitful linear control theories such as H_∞ theory.

抄録全体を表示

In research of biped walking robot, energy-efficiency is an important issue. We have proposed an optimal trajectory planning method based on a function approximation method, and applied it for 2D biped walking model. With this method, we obtained the solution of minimal square integration value of the input torque under equality state constraint condition. In this study we further consider-ed inequality state constraint to restrict the range of joint angle, and applied it for the model with upper body mass. In addition, we conducted the experiment to verify the effectiveness of this method. We realized the stable walking of 0.6 s period, 0.3 m/s. Finally, we evaluated the energy-efficiency by specific cost.

抄録全体を表示

The capability of detecting landmines by using Metal detector is oversensitive to the gap between the landmines and the sensor head. So the deminers scan the sensor head with following the shape of the ground surface. The mine detection robots should scan the sensor head by an above mentioned strategy. At this case they need the Gap and Attitude Control with following the shape of the ground surface. But there are no reports for demonstrating the effectiveness and impact related to the Gap and Attitude Control to mine detection robots quantitatively. This paper describes a study of Controlled Metal Detector, CMD. It has the ability of the Gap and Attitude Control for the sensor head. In the ability it generates the trajectory of sensor head with using the information of ground surface acquired by the 3 D stereo vision camera, so tracks the trajectory with averting a contact with ground surface. We verified the effectiveness and impact of the Gap and Attitude Control to mine detection robots quantitatively through the experiment by CMD.

抄録全体を表示

A simultaneous control for vibrations and positions of a controlled object is demanded in the fast-moving machine with a flexible structure such as cranes, transport systems and positioning machines in a plane. Particularly, the positioning machine in a plane has the mass distribution which varies due to a positioning command, thus, it is classified into a time-varying system. This paper presents a synthesis method of the robust input to control simultaneously the position and vibration of the time-varying flexible structures. It is supposed in this paper that the fast positioning machine in plane as the controlled object has the actuator system with a servo mechanism which follows the position or velocity command as a feedfoward control input. And the command is then calculated by the numerical calculation which simulates the feedback control by using the nonstationary robust controller designed by the generalized plant with structured uncertainties. Furthermore, this paper provides a practical methodology so that the command is independent from positioning distance and a schedule and it is also installed into hardware with the reduction of the required memory amount and computing load by the approximation of the command using the Fourier bases. The performance and robustness of the proposed input are examined through the numerical calculation compared with those of a command shaped input. And then the usefulness of the proposed input and the procedure of its installation are obtained.

抄録全体を表示

A novel magnetic suspension system with three flux path control modules was developed. The module consists of a ferromagnetic plate, a voice coil motor (VCM) for driving the plate and a displacement sensor for detecting the position of the plate the sensor is comprised of a V-shape plate spring and four strain guages pasted on it. The ferromagnetic plate is inserted into the gap between a permanent magnet and a suspended object (floator). The lateral position of the plate is controlled with the VCM and the sensor. Since the flux from the permanent magnet to the floator varies according to the position, the amplitude and direction of the attractive force acting on the floator can be adjusted by using multiple modules. Stable suspension was achieved by applying PD control. A fluctuation was observed in the position of the floator. It was reduced by feeding back the lateral motions of the floator. The two- or three-dimensional noncontact manipulation of the floator was also achieved in the developed magnetic suspension system.

抄録全体を表示

This paper presents the design method of a preview-sliding-mode controller for discrete-time linear invariant systems with disturbance. As well as the integral sliding mode controller in continuous time, the control law consists of two components, a linear component for the nominal system, and a variable structure component to cancel the distubance. Since the linear component is designed by means of optimal preview control technique, the closed loop system achieves optimal tracking performance robustly.

抄録全体を表示

The various motions of hula-hoop in vertical plane were analyzed using the shooting method and ordinary numerical integration. The results are summarized as follows : There exist many types of motion depending on the ratio of vibration amplitude of supporting point and the length between the center of gravity and supporting point of hula-hoop, namely, synchronized rotation, subharmonic rotation, subharmonic vibration, subharmonic reciprocal rotation which vibrates with amplitude lager than π, chaos and so on. The solutions such as the synchronized vibration or rotation bifurcate to chaos after period doubling bifurcations. There are two types of chaos, namely the chaos with dominant vibration and the one with dominant rotation. Because of gravity, the co-existing solutions in the same regions on the motions of the horizontal plane appear in different regions each other on the motions of the vertical plane. The 1/2-subharmonic rotational solution composed of two different rotational patterns was found, this type of solution was not confirmed in the motions of the horizontal plane.

抄録全体を表示

An ultrasonic linear actuator with high precision and high thrust has been intensively investigated. As a result, we proposed the actuator with elastic hinge structure between a vibrator and a piezoelectric element. The proposed actuator was compared with conventional linear actuators without elastic hinge by using a finite-element analysis considering piezoelectric effect. Results of analysis show that the proposed actuator could use the resonance phenomenon more effectively and the output power of the proposed actuator was larger than that for conventional linear actuators with not elastic hinge because the ideal vibration modes are generable. Moreover, from the analytical result, it is confirmed that the proposed actuator can be generated elliptic motion of arbitrary form.

抄録全体を表示

Authors are aiming at system construction to make the load descent to the bottom of the hole and to make it turn for decided direction. The load is hung with two ropes, and the direction is done by rotating the top part where the rope is installed. In that case, the situation that a rope each other intersects along with the rotation of the top part. Therefore, the gyration is caused on the load. It is though that such behavior is the same one caused by the winch. However, most of the report for the winch is the one that the optimum conditions when the swing is not caused, and it transports it to the load in the straight line are induced. The rope for hanging temporarily causes intersection mutually, and when an irregular movement is caused, it is not analyzed. In this report, the gyration of the load for this case was analyzed.

抄録全体を表示

Thin plate structures whose features are light and easy to treat have been used to various product. In order to improve rigidity, the structures have been processed to curved or concavoconvex plates. Dynamic characteristics of the thin plate structures haven't been considered because of the difficulties of design. Caribbean steel drums, which are percussion musical instrument have a spherical shell with many bends and grooves, it has various musical scales. The dynamic characteristics of the steel drums are tuned by its bends and grooves. This paper presents investigation of the guideline for making the thin plate structure with bends and grooves. Experimental modal analysis is used to identify the vibration mode of the steel drum. Then the paper is an attempt to bring out a possibility of vibration mode tuning of the thin plate structures with bends and grooves.

抄録全体を表示

In designing turbo compressors driven by high-speed motor directly, there is a rotordynamic problem due to lowered bending mode frequencies. In order to support such flexible and high-speed rotating shaft, active magnetic bearing (AMB) will be one of the solutions. In this paper, the design and test results of the AMB system for such a compressor that has two compression stages are discussed. In a digital processing of AMB control, a large phase lag in high frequency domain cannot be avoided. In order to solve this problem, the following control methods are presented. For levitation control, a practical controller design that uses a combination of phase shifting filters and second order low-pass filters is presented. For unbalance control, a synchronous filter that has an arbitrary phase shift at the reference frequency is applied to cross over the first bending critical speed. By adopting these control methods, very stable operation from zero speed to the rated speed of 55 000 min^-1 was realized.

抄録全体を表示

In the Hot-Rolling process, when a thin strip runs on the Run-Out-Table (ROT) at high speed in the state of non-tension (a head or a tail of a strip), the defect resulting from the running instability poses a chronic problem. Moreover, for the running unstable phenomenon, the maximum line speed is restrained, and has also become a prevention factor of productivity. In order to solve this problem, various methods are proposed from the former, but it has come to eradicate completely. In this paper, we describe the equation of motion of the strip which runs on the ROT at the first. In the next, we propose the equivalence principle (eigenvalue problem) of the ROT running unstable phenomenon and the buckling phenomenon.

抄録全体を表示

A leg-wheel robot has mechanically separated four legs and two wheels, and it performs high mobility and stability on rough terrains. In this paper, the strategy for the leg-wheel robot moving over large rough terrains is described. First, topographical features are classified for the large rough terrain movement. They are classified into 13 patterns by the combination of terrain surfaces. In order to move over all classified terrains, three gaits are proposed as adaptive gait for large rough terrain. Those three gaits are as follows : 1. Gait for an upward step : the forefoot landing point is higher than contact points with the ground of wheels, and the robot raises the body toward the forefoot landing point. 2. Gait for a downward step : the forefoot landing point is lower than contact points with the ground of wheels, and the robot lowers the body toward the forefoot landing point. 3. Gait for getting over an obstacle : the forefoot landing point is not higher than contact points with the ground of wheels, but the robot raises the body as high as possible.

抄録全体を表示

A leg-wheel robot has mechanically separated four legs and two wheels, and it performs high mobility and stability on rough terrains. The adaptive gait for large rough terrains of the leg-wheel robot is composed of three gait strategies. In this paper, the gait for an upward step, which is one part of the adaptive gait, is described. The proposed method is evaluated by simulations and experiments. The point of the flow of the gait for an upward step is described. When the robot reaches an upward step, it does not come to advance easily because it can not go up the upward step by the normal gait. At this time, the difference between actual wheel angles and desired wheel angles grows. Starting point of the step is detected by using this information. The system stops the body, and prepares for going up the step. In the preparation, the robot changes footsteps in order to set all legs to starting points of their work space. After that, the robot can raise the body on the step supported by all legs and wheels. The purpose of supporting using all legs and wheels is to enhance stability and to reduce energy. To raise the body, the following items are needed : I. Acquisition of target rise height of the body. 2. Correspondence to difference between target and actual height.

抄録全体を表示

A leg-wheel robot has mechanically separated four legs and two wheels, and it performs high mobility and stability on rough terrains. The adaptive gait for large rough terrains of the leg-wheel robot is composed of three gait strategies. In this paper, the gait for a downward step, which is one part of the adaptive gait, is described. The point of the flow of the gait for a downward step is described. When the robot approaches a downward step, a forefoot touches the surface deeply. It forecasts the existence of the downward step by the information on the forefoot's touch point. After that, the robot does the step edge searching operation. This searching operation is the point for going down the step, since the robot fell under the step if it has walked without knowing the step. When the body goes down the step a little, the load sharing ratio of legs increases so that the load of the body rests upon legs. Therefore, the robot finds the edge of it, and it changes footsteps for preparation of going down the step. After the preparation, it can lower the body from the step supported by all legs and wheels. To lower the body, the following items are needed similar to the case of an upward step : 1. Acquisition of target value of lowering the body. 2. Correspondence to difference between target depth and actual depth.

抄録全体を表示

A leg-wheel robot has mechanically separated four legs and two wheels, and it performs high mobility and stability on rough terrains. The adaptive gait for large rough terrains of the leg-wheel robot is composed of three gait strategies. In this paper, the gait for getting over an obstacle, which is one part of the adaptive gait, is described. The proposed method is evaluated by simulations and experiments. The point of the flow of the gait for getting over an obstacle is described. When the body reaches an obstacle, it does not come to advance easily. In this case, the robot can not always understand the height of the obstacle, since its forefeet sometimes do not touch it. Therefore, the robot raises its body as possible as it can, and gets over the obstacle. After getting over it, the body is lowered until it touches the ground. The system judges whether the body touches the ground by the information on load sharing ratio of legs.

抄録全体を表示

A leg-wheel robot has mechanically separated four legs and two wheels, and it performs high mobility and stability on rough terrains. The adaptive gait for large rough terrains of the leg-wheel robot is composed of three gait strategies. In this paper, the integrated gait of the normal gait and the adaptive gaits for large rough terrain is proposed. The proposed gait has following features : 1. There is a path from a gait to any other gait. 2. The robot does not fall into the endless loop of detection, because it works whenever it detects something. 3. A gait changes finally to the gait for getting over an obstacle which has the maximum ability of movement when the robot can not move. The robot can move on rough terrains where irregular ruggednesses up to 0.2 [m] in height or depth exist by using the integrated gait. The effectiveness of the integrated gait is verified through simulations and experiments.

抄録全体を表示

This paper deals with simultaneous classification of shape, size, and softness of cylindrical objects by using soft tactile sensor array system of a five-links single robotic finger. The front surface of each link is covered with semicircular silicone rubber equipped with 235 small on-off switches. The on-off data from these switches obtained during grasping an object is transformed into a spatial-temporal matrix form. As 8 cells around the contact switch is considered useful to extract the local spatial-temporal character of contact physics, the frequency of the 8 cells patterns composed of 0-1 data around the switch contacted is obtained for each object and then used to form a contact-feature vector. This vector is obtained 10 times of experimental trial, corresponding to each object. The vectors are classified by Mahalanobis distance for 27 objects (3 shapes, 3 sizes and 3 kinds of softness) resulting in 48 grasping postures. By using the most effective 7 kinds of 8-cells patterns, over 95% classification accuracy is obtained.

抄録全体を表示

The concept of a virtual arm wrestling system for force display communication analysis is proposed. The prototype system of a 5-DOF force display system with 4 air cylinders and a force sensor is developed for the affect display and interaction of virtual human on the basis of human nonverbal behavior and physiological measurement in arm wrestling. By using the system, the relations between force display and physiological index of peripheral skin temperature of fingers associated with circulation dynamics in response to forced actions are examined, and the effectiveness of the system for the analysis of force display communication characteristics is confirmed.

抄録全体を表示

We have proposed a novel autonomous bolt loosening detection technique using thin plate type sensors to keep integrity of machines and structures. The thin plate type sensor consists of a thin plate and piezoelectric elements and bolt loosening is detected by the natural frequency change of the plate. The validity of the sensor is shown by experimental results in previous works. However, the edge length of the sonsor is six times of the diameter of the target bolt and too large for practical use, so that it is desired to miniaturize the sensor. We have also proposed to use an oscillator circuit whose oscillating frequency is determined by the natural frequency of the sensor to evaluate the natural frequency change induced by bolt loosening. However, the oscillating frequency of the circuit does not coincide with the natural frequency and difference between two frequencies is sensitive to circuit parameters. In this paper, we propose slit cut thin plate type sensor as a miniaturized sensor and modify the oscillator circuit for natural frequency evaluation. The slit cut thin plate type sensor consists of a plate that has slits and a ring type piezoelectric element. The slits of the sensor eliminate degenerate modes that have harmful effects on natural frequency tracking and improve the tolerance for noise. The modified oscillator circuit is based on positive velocity feedback and the oscillating frequency of the circuit coincides with the natural frequency perfectly.

抄録全体を表示

The aim of this research is to investigate a new approach to the development of the system which supports inexperienced operators who are trying to acquire the machine operation skills. In this approach, we consider the support system which has the following functions ; The system has capability to lighten the burdens imposed on inexperienced operators by using a controllable assist. Furthermore, the system has capability to reduce the effect of the assist according to the operator's skill. In this paper, two different tasks for the operation of a rotary arm with a pendulum are treated and a support system for the acquisition of the operation skill is constructed. We try to show the skill level transition of a trainee and investigate the process of skill acquisition and the success rate of each task. Then we discuss the validity of our support system and demonstrate that trainees can acquire operation skills by using our support system.

抄録全体を表示

The purpose of this study is to develop a new plastic forming process to fabricate a laminated spur gear that has two layers composed with the different materials in the radial direction. The whole processes are composed with a set of drawing-ironing process to form the pre-from for the outer material and die forging process to hold together two materials as a unit of a gear and simultaneously to form the outer gear tooth shape. The divided metal flow method in the die forging process was adapted to fill up the die cavity with the metal under the low working pressure condition. In the experimental simulation of the die forging process aluminum and copper were employed for the inner layer material and for the outer layer material of the laminated gear. The influence of the forging conditions on the working pressure and the metal filling up into the die cavity were quantitatively evaluated. As a result of the experiment the realization of the new process to fabricate the laminated spur gear was confirmed with the different materials.

抄録全体を表示

Transient traction characteristics between rail and wheel have been investigated with a rolling-sliding contact type of frictional machine under dry condition. The experimental results show the effects of contact pressure, rolling velocity, slip ratio, surface roughness and hardness, which have important influence, on the traction characteristics. Until traction coefficient reaches the peak after a test start, surface roughness and hardness decrease. During traction coefficient decrease after the peak, surface roughness and hardness increase rapidly by wear on the rolling-sliding contact surface. Moreover, it is thought that the primary factors, which traction coefficient increase immediately after a test start, are based on surface roughness, hardness, and boundary films (oxide film, reaction film, adsorbed film).

抄録全体を表示

This paper deals with the tribology characteristics estimation of slide-way surface finished by scraping. The experimental machine measuring the friction force and floating displacement for slider with slide-way surfaces was developed. Two types of specimen with scraped surface and ground surface were prepared. By comparing the friction coefficient and the floating displacement of both specimen, the effect of the surface property on the sliding characteristics was examined. Though friction coefficient of the ground surface is lower than the scraped surface for any sliding speed, the floating displacement is large. The stimulated hydrodynamic lubrication of the ground surface was clarified from the Stribeck characteristics. The surface ruggedness of the scraped surface releases the surplus lubricant. As a result, in low-speed sliding, the scraped surface becomes a tends toward boundary lubrication, and there is a small floating displacement which seems to enable the high-precise guide.

抄録全体を表示

This paper presents the results of experiment and analysis from view of structural mechanics for brake noise that is serious problem of motorcycle. Some brake bench tests were conducted to some cases of friction force distribution, and it was found that the cause of brake noise was stick-slip effect between brake disk and pads. And it was clarified that the stick-slip could become the exciting force of the disk by the fastening-sliding simulation by FEM. Finally, eliminating method of brake noise was proposed according to experimental and analytical results.

抄録全体を表示

When a bearing roller is in contact with raceways, excessive pressure peaks occur at the ends of the contact rectangles. They are called edge loading. Roller and/or raceway profiles are usually crowned to prevent edge loads. Lundberg developed a logarithmic function as a crowned profile. The profile gives an axially uniform pressure distribution. Johns-Gohar improved the function for convenience of manufacturing. However, the Johns-Gohar profile yields edge loading when the roller is tilted. Also, the profile allows no straight portion on the roller surface although it is desirable to have a flat region from the viewpoint of machining. In this study, we modified the Johns-Gohar logarithmic function to exclude edge loading even when the roller is tilted allowing a flat region. Three parameters, K₁, K₂ and zm, are introduced into the Johns-Gohar function. These have the following meanings : K₁ : coefficient of load, K₂ : ratio of crowning length to effective contact length, Zm : crown drop at edge of effective contact length zone. In addition, a mathematical optimization method is used to efficiently determine a set of the parameters. An optimization problem is considered to minimize the maximum contact pressure P_max, or to maximize the rolling fatigue life L₁₀. A Rosenbrock method is adopted as the optimization algorithm. The method requires no evaluation of gradients of the objective function. Pressure distribution is calculated by making use of a multilevel method. Some examples are demonstrated to verify the proposed method for both P_max and L₁₀.

抄録全体を表示

Regular striations exist on bearing surfaces due to machining. In this study, a mass conserving elastohydrodynamic lubrication model of an engine journal bearing having regular striations on a surface has been developed for analyzing lubrication characteristics. The model is based on a modified Elrod's cavitation algorithm and a theory of surface roughness. The cross sectional shape of the regular striations is formed into by isosceles trapeziums. The model was applied to a con-rod big-end bearing and the effect of striations on friction power loss was calculated. Friction power loss of the bearing with circumferential striations is lower than that of the bearing with transversal striations and is as much as that of the bearing with a smooth surface. The calculated results of the model were compared with those of an elastohydrodynamic lubrication model without cavitation algorithm. Though the calculated values are slightly different, the same tendencies are obtained.

抄録全体を表示

The study deals with the development of a movable machine tools with multi spindles and axes that can efficiently process large-sized parts to expect an additional value. The main specification of the machine tool is not having the major construction such as bed, column and saddle absolutely. Instead, the machine tool is built by only linear motor rails and beams to support. The developed machine tool can reduce the cycle time for cutting large materials by means of multi spindles and axes, equipped with 6 to 9 spindles and simultaneously control up to 40 at maximum. In addition the installation area of the machine tool is approximately 120% of area that the material occupies. The previous report explained the basic specification of the machine tool, its concept and performance evaluation. Then, this report presents the management of simultaneous movement, the division of NC program for each spindle and interference avoidance of multi axes, as well as the method of tool path generation to confirm the rapid production of large sized die and mold.

抄録全体を表示

Developments with short-term and lower cost are strongly required for shorten products life cycle. In press forming, many trials are needed to design of mold and to decide optimum forming condition. For these problems, FEM simulation is used to predict the result of processing instead of real test. The other side, TAGUCHI method (robust design) in also used to decide optimum processing conditions with narrow dispersion. Generally, production conditions have some factors such as tolerance, order entry, date of delivery, material price and machining cost. In the actual production stage, there're many kinds of suitable production conditions, e.g. accuracy priority, total cost priority and so on. Therefore, the optimum forming condition is changed by the order of priority. In this study, spring back of warm press forming of magnesium alloy plate is intended. First, material property of magnesium plate and friction coefficient of lubricants (Teflon sheet and two types of oil) are investigated to use for FEM calculation data. Next, spring back simulations performed under various processing conditions are decided by TAGUCHI method. Average spring back and its dispersion are estimated by TAGUCHI Method with the results. Then, productivity such as accuracy, total cost, total working time and non-defective unit rate are estimated at all forming condition combination. Finally, optimum processing conditions are decided each priority. And actual spring back test results are performed to confirm the predictions. It is concluded from the result that (1) The proposed method predicted optimum processing conditions effectively in each priority and (2) The predicted results conformed to the results of the actual spring back test.

抄録全体を表示

Free-form surfaces can be produced by integral equations and polyharmonic functions. This method is useful for multidimensional interpolation, because scattered data can be used and off-surface normal points are not used. A smoothing method using integrated polyharmonic functions, which is useful for local smoothing, has been proposed. However, there are no smoothing methods suitable for these free-form surfaces produced by integral equations. This paper describes a smoothing method using a least-squares approximation for the free-form surface produced by integral equations. To investigate the effectiveness of this method, several numerical examples are given.

抄録全体を表示