In the field of precision measurement and positioning, air-type anti-vibration apparatuses are commonly used. There is the pressure fluctuation of supplied air and then the position fluctuation of isolated table due to the supplied air pressure is generated. This pressure fluctuation can be usually suppressed using the multi-connection of air regulator. However, the drawback is that this connection method produces the pressure loss.
Then, in this paper, a method to reduce the position fluctuation is presented. Firstly, the mechanical structure and the control scheme of air-type anti-vibration apparatus are briefly clarified. Secondary, the fluctuations of supplied air-pressure, air-spring pressure, and isolated table displacement are shown respectively and the feedforward control scheme to compensate the position fluctuation is derived. In detail, several feedforward compensators are derived based on the control system including the disturbance model. Finally, remarkable experimental results are shown.

抄録全体を表示

The steering wheel of a steer-by-wire (SBW) vehicle is free from road-disturbance because of the lack of mechanical connection. There is less need for disturbance attenuation and the SBW actuator can be mounted rigidly on the vehicle chassis. A bench test using actual SBW system demonstrates that the steering stiffness becomes larger than the electronic-power-steering (EPS) stiffness. A driving experiment and a closed-loop simulation show that the increase of this stiffness plays a crucial role in reducing work load for the SBW driver.

抄録全体を表示

A shrink fitter is a ring-shaped new machine element to join mechanical components with different coefficients of thermal expansion. As an application of the shrink fitter several optical lenses were shrink-fitted in a lens-barrel using the shrink fitter. The optical axes of the several lenses in the lens-barrel agreed with each other regardless of changes in room temperature. The scanning lens assembled by the shrink fitter could focus the laser light well even over a wide scanning width. If such a scanning lens was incorporated into a laser microscope, object surfaces could be observed over a wider area, compared with the conventional microscope. In this study we have developed a new type of laser microscope with a field of view of 10 by 8 mm. The pixel number in the laser scanning direction of 10 mm was 20,000 and 16,000 in the perpendicular direction of 8 mm. Thus, one field of view of this laser microscope has 320,000,000 pixels. The observation result of some surfaces by this laser microscope are reported.

抄録全体を表示

In this paper, position information based forcefree control is proposed in order to realize flexible motion of articulated robot arms without force or torque information sensing. The proposed position information based forcefree control uses torque observer instead of torque information sensing, which enables flexible motion for more general articulated robot arms. The proposed position information based forcefree control was assured by experimental results of an actual articulated robot arm. Moreover, the proposed position information based forcefree control is compared with the previously proposed forcefree control using torque monitor.

抄録全体を表示

This paper describes a strategy of null space force control of a redundant manipulator. As well known, robot is utilized in various industrial fields and it is preferable for the robot manipulator to have multiple degrees of freedom motion. Several studies of kinematics for null space motion have been proposed. However, the stability analysis of null space motion in force control is not enough. Then, passivity based null space force control is proposed. In this strategy, work space observer based control (position control) and null space control which can obtain desired force response are constructed. Moreover, its null space controller compensates stability of null space motion. Using L₂ disturbance suppression property of the system, an influence of force torque to each joints can be suppressed. Desired force response to the object is realized by force PID controller. The validity of the proposed approach is verified by simulation and experiment of 4-link redundant manipulator.

抄録全体を表示

Fabrication of very porous scaffold for regeneration of organs with high metabolic rate is reported. Polycaprolactone (PCL) powder was mixed with fine grains of sodium chloride as filler and SLS (Selective Laser Sintering) processed to develop an object including fine flow channel network. The object was rinsed with water to desolve the salt, and a high porosity of 90% was successfully obtained. In addition, unsintered powder in the channels was effectively removed owing to disappearance of the filler. Through micro-CT observation, it was confirmed that channels of which diameter was smaller than 1mm were fabricated. Measurement for the amount of residual salt proved that the salt can increase salt concentration of culture media no more than 1% of that for physiological saline solution. Result of culture test is also reported.

抄録全体を表示

This paper reports two dimensional machining tests of a soda glass conducted under high hydrostatic pressure up to 200 MPa. A new device has been developed which enables us two dimensional machining test and in-situ observation by an optical micro scope. The device consists of a pressure vessel, a high pressure pump, a two dimensional machining tester and an optical microscope system. Water is used as pressure medium. The two dimensional machining tester consists of an X stage, a stepping motor that drives the stage, a single point diamond tool, a load cell and a tool holder. The load cell is set on the X stage, and a work piece is mounted on the load cell. The load cell measures both principal force and tangential force simultaneously. All of these mechanisms are installed in the pressure chamber. They work well even under high hydrostatic pressure up to 200MPa. The tool and a work piece are observed by a microscope placed outside of the chamber through a sapphire window. Image of machining process is observed by a CCD camera. Machining tests of soda glasses were conducted using single crystal diamond tools of various rake angles. Three types of chip formation were observed; chipping type and discontinuous type were observed under 0 MPa, and 100 MPa, whereas continuous type was observed under 200 MPa. Measurement of cutting force under 0 MPa and 100 MPa revealed that external hydrostatic pressure is effective to increase both principal force and tangential force. Machining mechanism under hydrostatic pressure is discussed.

抄録全体を表示

The study deals with 5-axis control micromilling of such a complicated small shape as a human head by use of a diamond pseudo ball end mill. In the fields of micromachining, the milling with diamond cutting tools plays an important role due to the capability of creating 3-D complicated shapes with high accuracy. A wide variety of microstructures have been created with ultraprecision machining centers. Nevertheless, these structures seem to consist of a simple shape. Thus, the study proposes a CAM system for 5-axis control ultraprecision machining to create complicated microparts. 5-axis control micromachining of a BOSATSU was conducted to verify the practical effectiveness of the developed system. Based on the 3-D restored data of BOSATSU, the system can create the complicated statue, taking account of the collision between a tool and a workpiece. From the experimental result, it is found that the CAM system for 5-axis control ultraprecision machining has the potential of accurately producing 3-D small complicated shapes.

抄録全体を表示

This paper deals with the rough cutting method using 5-axis control machine tool and the tool path generation method to machine complicated shapes efficiently such as overhanging shape that requires the inclination of cutting tool. In general, conventional rough cutting methods employ the contour milling with 3-axis control. However, these rough cutting methods were not always efficient, because several set-up changes were required to machine complicated shapes. The study proposes the new rough cutting method for 5-axis control machining, which uses a plunge milling that has been used only for 3-axis control machining. Consequently, the rough cutting with the high efficiency of plunge milling and the flexibility of 5-axis control can be realized. In order to achieve the method, it is necessary to generate the tool path in consideration of the tool interference with not only the target shape but also the remained part. Therefore, the study developed the tool path generation method by expanding the method which uses the 2-dimensional configuration space technique. Finally, the developed method is implemented to the original CAM software. As a result, it is experimentally found that the system enables the rough cutting of complicated shapes with 5-axis control with only one set-up.

抄録全体を表示

This paper deals with an optimum design method for machine tools structures using neural networks. Machine tools structures such as a bed or a column have ribs, which layout correlates with their performance. A static and a dynamic stiffnesses, a natural frequency and a thermal displacement are hired as evaluation functions. Some of them are obtained by FEM and learned by the neural networks to recall those of unlearned rib layouts. The evaluation functions of all prospective lib layouts are estimated in short time and the optimum rib layout can be obtained by choosing that with high values. The additional learning method is proposed to decrease the estimation error especially for exclusive data. The estimation error becomes less than 4% and it leads to realize the multi-object optimum design method. Two multi-object optimum designs were carried out using the whole machining center model. The estimation error is approximately 8% and the value of evaluation function is improved as 18%. In the case of layout for many ribs, the margin of improvement decreases because the problem becomes complex. The proposed system is effective for the machine tools design in early or concept design stages.

抄録全体を表示

We propose a new method for joint angle and torque estimation by using ultrasound. The ultrasound is emitted from the surface of skin. The estimation is carried out based on the feature value extracted from the reflected wave from inside of living body. The feature value changes as the movement of the muscle relating to the joint. We conducted an examination of simultaneous joint torque and angle estimation in dynamic motion of human elbow joint. Neural network and Multiple linear regression was employed as the estimator. Correlation coefficients and Mean absolute error between estimated data and measured data were calculated. The results show that the estimation was successful, though the error increased with time course.

抄録全体を表示