An artificial potential method has two problems of local minimum and computational cost. In order to resolve such problems, this paper proposes the utilization of a spline surface and a domain reduction method. A spline surface that interpolates arbitrary shaped boundaries is used as an artificial potential to guide a robot for global motion planning of a mobile robot. The domain reduction method resolves the local minimum problem by reducing a domain that maps on a free space in a configuration space. The spline surface is generated over the free space by assigning appropriate boundary conditions to the boundary of the free space. A moving obstacle is represented as an inner boundary of the domain. Some simulation experiments are applied to some complicated environments. From these experiments, this paper shows that a mobile robot can move to a target position selecting a wait action and an evasive action automatically in order to avoid a moving obstacle in a maze. Additionally, this paper shows that the proposed methods are applicable to a wall obstacle with arbitrary shaped boundaries.

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A surface acoustic wave (SAW) linear motor performs large output force of about 8 N and high speed of more than 1 m/s. A stroke of the motor, however, is limited to about 30 mm due to its configuration. A method to increase the stroke limit has been proposed, then a long stroke SAW linear motor was fabricated. The stroke was improved up to more than 100 mm. The fabricated motor worked successfully. The maximum output force was 24 N and traverse speed was 160 mm/s.

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This report aims to find the influence of work materials on drill breakage when machining hardened sintered steels, and to clarify the mechanisms of the drill breakage. The work materials having different hardness obtained by the different heat treatment were prepared, and drilling, and turning tests were carried out. The main results obtained are as follows : Fracture of the drill occurs when drilling materials of high hardness. During drilling the high hardness sintered steels, cutting temperature becomes high, and so that thermal expansion caused a high friction between the drill and surface of the hole drilled. In the effect the drill breaks down, when the friction force exceeds the drill's twisting strength. However, in drilling the low hardness sintered steels, the cutting temperature becomes low, and the thermal expansion is also small, furthermore yield strength of their steels is small, so that the friction force does not become large, and consequently the drill does not break down.

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The measurement device has been developed which could measure various kinds of dynamic accuracy of multi-axis NC machine tool in this study. The DBB device has been widely used to examine a circular motion and also to estimate an assembly error of machine tool. Grid scale encoder device is a commercially available device which can be used for accuracy checking of the several kinds of two dimensional interpolation in the non-contact mode. The laser interferometer is the basic equipment for measuring positioning errors in a single motion and measuring data are used to compensate them. In case of multi-axis NC machine tool, it is important to estimate the interpolation accuracy under simultaneous multi-axis controlling in which tool motion will be much more complicated compared with that of three axis NC machine tool. The methods of testing and evaluating the accuracy and repeatability of positioning of NC machine tool axes are specified by ISO 230-6. On the other hands, the methods of them which can be applied for multi-axis NC machine tool is not specified and the standardized measuring device is not realized. The purpose of this study is to develop the on machine measuring device and the measuring methods which can examine the interpolation accuracy of multi-axis machine tool under the no-load condition.

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The effect of machining atmosphere in ultrasonic vibration cutting on the cutting force and chip formation was studied in this report. Some vibration cutting experiments have been conducted under the several kinds of atmosphere such as the air, inert nitrogen gas, cutting oil and oil-mist supply. In order to vary the gap size between tool rake face and the chip in each vibration cycle, newly proposed cutting experiment using resonated-horn-type work piece was used. The displacement amplitude and stress amplitude at the cutting point can be varied continuously in this device. From the viewpoint of the smoothness of the chip surface, the lubricating property at tool-chip interface seems better in the air than in the nitrogen atmosphere when ultrasonic vibration cutting was conducted. But absolute decreasing of the cutting force by the lubricating effect was smaller than that by the effect caused by the dynamic response of high-cycle vibration. Also it was shown that the cutting force reduction ratio by using the oil or oil-mist was 60% to 75% even if the vibration was applied or not. On the other hand, the amount of the contribution for the dynamic cutting force reduction can be larger than the effect of the lubrication and it can be varied by changing the vibration and cutting conditions.

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This paper presents an intelligent process planning system for end milling process. Machining features are input for the system which are given by the differences between the shape of the raw material and finished part. Several sets of canned cycles, which give the CL data for the machining of the part from raw material, are selected for all machining features. The optimum set of the canned cycles is decided from all sets of the candidates under the criterions, for examples, manufacturing cost minimum. Cutting tests are conducted to verify the validity of the system and it becomes clear that this system can make a reasonable process for the milling.

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Cone-shaped diamond-tip field electron emitter arrays (boron-doped synthetic single crystal diamond chip, (100) face, type Ib) were fabricated utilizing the SOG (spin-on glass) mask and oxygen reactive ion beam, and characterized. The tip radius of the fabricated diamond emitter arrays was less than 30 nm. The threshold electric field of 7.5 V/μm and the work function of 3.36 eV were obtained from the diamond-tip field emitter array. The experiments on the field emission of the diamond-tip field emitter array at the applied voltage of 1000 V for 400 min show that the field emission current increased gradually at 60 min. The mechanism of this phenomenon was investigated in atomic level by employing the first-priniples molecular-dynamics simulation method. The simulation results show that the mechanism of the phenomenon was not the movement of atoms of the diamond but the movement of atoms of the hydrocarbon deposited during the field emission.

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This study focuses on the deposition of higher density a-C films by sputtering enhanced by electron beam excited plasma. Energies and densities of Ar ions and electrons in plasma were controlled by changing the deposition conditions such as target-substrate distance, the target bias voltage, pressure in the chamber and discharge voltage between the cathode and the anode. As a result, a-C films with different densities ranging from 1.7 to 3.1 g/cm³ were synthesized. XPS analysis indicated that the ratio of sp₃ bonding was higher in the a-C film with the density of 3.1 g/cm³ than that of 1.7 g/cm³. The difference of surface profiles was not observed from the a-C films with various densities, however, the friction test revealed that the frictional property of a-C films depends on the density of a-C films.

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It is pointed out that joints in precision machines such as machine tools influence greatly on the thermal characteristics of the machines. Therefore, many researches on the thermal contact resistance have been carried out and its formulation has been tried. However, in most of research, uniform contact condition in the joints is assumed and the nominal contact pressure obtained by dividing the nominal contact area by loaded force is used to get the relationship with the thermal contact resistance. Moreover, it is known that real contact area is much smaller than the nominal contact area and is rare to contact uniformly all over the contact surface of a joint. Accordingly, in this paper, we propose the quantitative measuring method of thermal contact resistance in considering of the real contact area of the joint and make clear its validity and the possibility of formulation of the resistance. The conclusions of this paper are as follows ; 1) The grasping of the real contact area of the joint is necessary to measure the qualitative thermal contact resistance of the joint. 2) The thermal contact resistance can be measured quantitatively with the proposed method and formulated by changing the contraction rate of heat flow with the real contact ratio of the joint surface in the equation based on the Holm's principle. 3) The relationship between the thermal contact resistance and the real contact ratio is independent of the machining method of the joint surface in the range of grinding and polishing.

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The technological innovation using the extreme ultraviolet wavelength (EUV) with high brightness of synchrotron radiation is actively advanced. In order to effectively utilize such light, it is important to develop the technology that produces and evaluates the optical elements with very high surface accuracy. The point diffraction interferometer is an interferometer that has inherent high accuracy using a circular aperture with a radius comparable to the wavelength of light. We are constructing a point diffraction interferometer as a profile measurement sensor, which can be also utilized for alignment of the EUV optical system. The optical system is consisted of single-mode optical fiber and fringe scanning using the laser source of visible light. But, the extra interference and diffraction waves are included for original interference fringe. In this report, the effect of the temporal coherence length of light source on the measurement accuracy was investigated by experiments and simulation analyses. As the result, when adjusting optical path difference of the object and reference waves the optimal, it was shown clearly that high accuracy measurement is possible. Furthermore, if a light source of the shorter coherence length is used, the alignment will become easy and its accuracy will also improve more.

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This This paper describes a control method for moving object tracking on an active stereo vision robot. Our developed robot has 3 rotational axes ; two are for camera-pan motion and one for base rotation, and then has structural redundancy to track the target object. The aim of our approach is to achieve both requirements of rigid tracking and accurate position estimating, and then the characteristics of each rotational axis are considered form the viewpoint of dynamics. Since the base axis has heavier inertia than the camera axes, the camera-pan motion is preferable to realize rigid tracking in the high gain servoing. On the other hand, the base is required to face to the target to prevent the position estimation accuracy from getting worse, so that the base would turn to the target in the slow response. The former motion is realized in the image-base visual servo control law, while the latter in the mechanical impedance control law, and then these control laws are unified in the proposed method. Additionally, the Kalman filter is introduced for prediction of the target motion. The filter contributes to more precise target position estimation. The validity of our method is confirmed in the physical experimental results.

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The conformance of a manual wheelchair used to be evaluated from the viewpoint of human engineering but can now be evaluated biomechanically. However, the musculoskeletal motions of the upper limbs are very complicated, and evaluating the relationship between muscular strength and driving force is theoretically possible but not easy. Until now, the relationship between output force distribution and muscular strength in human limbs has been discussed under the theoretical back ground of the coordination of bi-articular muscles and mono-articular muscles. In the present study, the details were examined for the application of this approach to a manual wheelchair propulsion. The relationship between seating position and driving force was clarified. Proposal method in this study may be of use when prescribing a manual wheelchair.

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So as to improve the road safety, not only the safety of the vehicles but also the nature of drivers has to be considered. This paper proposes a concept of automatic instruction system that instructs a driver to improve his or her safety of driving using image processing techniques. So to speak, the system substitutes for an instructor at a driving school. An example of the modules of the system is constructed : it warns the driver if he or she has forgotten to turn his/her head when the driving lane is changed. Changing lanes is recognized by extracting white lines. On the other hand, face turning is recognized by extracting face and nose regions. These two are done simultaneously and whether the driver follows the rule at changing lanes is judged. Experiments show the effectiveness of the constructed module. Additionally, interviews for subjects indicate the effectiveness of the concept of automatic instruction system.

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A surface encoder, which is composed of a 2D angle grid and a 2D slope sensor, is analyzed in wave optics. Based on the wave optics model, behavior of optical diffraction pattern on the photo-detector caused by 5-degree-of-freedom motions of the angle grid, which are the X- (Y-) movement, tilt motion about the X- (Y-) axis and rotation about the Z-axis, are investigated. The diffraction pattern on the photo-detector show different behavior in each of the motions. In addition, a new 5 degree-of-freedom measurement method is proposed based on the analysis results. This method uses a multi-cell photodiode instead of the QPD in the slope sensor. The principle of the new surface encoder and the design of the multi-cell photodiode are described. Simulation results based on the wave optics model are also presented.

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[in Japanese]

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