This paper describes a novel method of planning collision-free path for a translating mobiler in three-dimensional workspace. The safe path is found in short calculation time by the proposed method, so that it is feasible to be applied for real-time processing. Especially, in case there exist a lot of complicated obstacles in the workspace, the advantages of the method appear more efficiently. In general collision-free path planning methods, Configuration Space is often applied. Utilization of the space is very effective to plan the safe path, but it requires so much calculation time. In this paper, in order to get the calculation time shorter, rectangular parallelepiped forbidden areas are introduced, instead of the general forbidden area in the configuration space. To apply the rectangular parallelepiped forbidden area makes the interference detection of the path against the forbidden area much easier and faster, and moreover, it makes the determination of the direction to which the path goes definite. The validity of the proposed method is confirmed in numerical experiments.
In recent years, the relationship between the process planning and the manufacturing environment has been perceived as to be a core in the area of the CAPP. Even when making the process sheet for the same product, the manufacturing environment, such as people, facilities and enterprise communities, functions to produce the difference in process planning. This difference is derived from the thinking process of experienced engineers who produce the process plan. In this report, first the method regarding how the engineers think about the noticeable points when checking the part drawing is investigated and moreover it is expressed by the “thought model”. In addition, a concept of CAPP system, which can correspond to the difference of manufacturing culture-related environment is proposed using the neural network and on the basis of the thought model.
A new type of field-assisted fine polishing method for brittle materials has been proposed, which is developed for applying to the polishing on NC grinding machine without the vessel for polishing compound. In this method, the non-contact type polishing is realized with fluid grinding wheel which is covered with thick magnetic fluid film holding the abrasive grain. In this report, the surface polishing experiments are conducted on silicon wafers and the polishing characteristics are examined. The following results are obtained : (1) When the clearance between the polisher and the work surface exceeds the definite value, the polishing rate decreases extremely. (2) The use of water based magnetic fluid yields lower polishing rate but smoother surface in comparison with kerosene based magnetic fluid. (3) The surface roughness of polished surface basically depends on grain size and the roughness of the order of nanometers is obtained with fine abrasive grain.
The ultraprecision diamond turning is the best way to obtain optical surfaces on organic nonlinear optical crystals of soft and brittle in nature. The machined surface on chalcone organic nonlinear crystal is apt to become opaque with the passage of time. This paper deals experimentally with the cause and prevention measure of this opaqueness on chalcone. The transmittance of chalcone decreases and the surface roughness increases with the time after diamond turning. This phenomena are due to the recrystallization of chalcone after cutting. The wet cutting method which puts a waterdrop on a diamond tool can reduce the phenomena. The polymer coating just after wet diamond turning can solve the surface property change of chalcone perfectly. The coating will be able to work as the anti-reflection coating.
As semiconductor device geometries shrink, the need for silicon wafers with smaller surface micro-roughness is critical. In advanced device fabrication processes, rinse and ion implantation steps also can cause small but unacceptable roughnesses in oxide films and silicon-base materials, and the high-resolution measurements of the surface roughness using an atomic force microscope (AFM) have been performed. In this paper it has been shown that the measured micro-roughness of the polished silicon wafers using an AFM strongly depends on the sampling area size and must be treated with caution. When the micro-roughness shows a fractal nature, it can be analyzed by its power spectrum. An equation relating the fractal dimension to the micro-roughness (Root Mean Square) has been introduced and proved to be a powerful tool for the analysis of the surface roughness of various materials.
Diamond turning of single-crystal copper was carried out in several crystallographic orientations at a depth of cut of 300 nm. Transmission electron microscope observation and Laue X-ray analysis revealed that surface damage depends strongly on the crystallographic orientations of the copper, although turned surface features and continuous chip morphologies are independent. When turning is carried out along the  slip direction on the (111) slip plane, plastic deformation in the turned surface layer occurs mainly on the (111) planes parallel to the surface, and thus a fault in the stacking of the (111) planes occurs due to slip deformation. Surface layer crystals turned along arbitrary directions, except for the case of the slip direction on the slip plane, rotate towards the cutting direction, and the surface structure changes to a polycrystal composed of long narrow crystals. The longitudinal direction of each crystal is related to the slip direction rather than the cutting direction. When turning is carried out along the slip direction, as in the case of turning along the  direction on the (110) plane, the longitudinal direction of the crystals coincides with the cutting direction.
This paper proposes a low cost fabrication method using concavo-convex micro connection for high quality optical devices, and also describes the newly designed convex forming equipment for obtaining this micro connection. The distinctive feature of this micro connection is to use optical fibers which are formed convex cone shape on the ends of them by newly designed etching equipment, and to use optical lenses which are formed concave cone shape on the ends of them by also newly designed precise micro heating press machine. First of all, the experiments are performed for forming convex cone shapes on the ends of optical fibers which are optical elements of optical collimators, optical splitters and so forth. For an example, the convex cone shape whose top angle α is approximately 1.8 rad and the height H is approximately 4.7 μm is formed on the end of step index type single mode optical fiber. Then, the value of back reflection BR of its optical fiber is also obtained -60 dB compared with -28 dB on flat finished end fiber under using a wavelength λ=1.3 μm.
A sensor system to measure position and the orientation of a mobile robot has been developed. The system measures the robot's position and orientation every 40 msec with an accuracy of 10 mm, in range of 1.5m radius. In this system two or more infra-red LED marks are placed on the ceiling, and a 2D PSD sensor on the mobile robot faces toward them. The PSD senses relative position of a spot light from the mark, and the position and orientation of the PSD are calculated from the relative po-sition of the marks. Since pitching or rolling of the camera affects the 2D measurement, 3D measurement is incorporated. 3D position and orientation are calculated geometrically, using 3 marks. The emission of LED mark is controlled from the robot by sending infra-red light to the marks. Furthermore, lock-in amplifier is used to improve accuracy.
The present research aims at establishing an accurate and reliable methodology to estimate the heat quantity generated during the rotation of spindle and to evaluate the characteristics of the spindles employed for various types of machining. The technique proposed here basically depends on the accurate measurement of the change in the rota-tional speed of spindle during its free run. A new method is presented in the present report to measure the rotational speed of spindle accurately in a rotational speed range up to 100000 rpm by applying a reflective sensor system. The method developed here was applied to estimate the heat quantity of various types of spindle. It was clarified through experiments that the surface roughness of the spindle rotor affects the heat quantity generated, and also that the coefficients of the thermal expansion of the rotor and spindle housing affect the clearance between the two and consequently the heat genera-tion. The effect of air stirring by the bolt holes is also discussed.
This paper describes a measuring system for tooth profiles of a gear. This system uses the optical 2 point method and the high speed and high accuracy are planned. The system was made and measurement using the system was performed. As a result, the high frequency component caused by vibration was rejected from the measured result and the effect of the 2 point method was confirmed. Further, the repeatability error was improved. It takes within 1 minute to measure that. This non-contact system can measure tooth profiles of a gear 5 to 10 times as fast as the former contact measuring system can.
In order to generate a very precise aspherical surface by means of a rectification machining, it is most important to improve the measurement accuracy of the workpiece form deviation. Furthermore, on-machine type measurement is useful for total machining efficiency. In this study, an on-machine system for measuring aspherical form accuracy was developed for optical devices such as mirrors, lenses and their moulding dies. The characteristics of this measurement system are as follows : (1) The measuring probe on the table of the grinding machine scans the surfaces of the symmetrical and aspherical workpieces using an NC (numerical control) program. (2) A contact type of sapphire ball probe was supported with the air-bearing and its deviation on the workpiece surface is detected by the LVDT (linear variable differential transformer). In the measurement tests, a calibration ball with 22 mm radius curvature was measured by this system and it was found that a measurement form accuracy of about ±0.04 μm was obtained. In grinding tests of the tungsten carbide moulding die with the measurement system, a form accuracy of 0.1 μm P-V was obtained.
The scanning detection system for a narrow crack on a ceramic plate has been developed. When a laser spot is illuminated on a ceramic plate, the laser is diffused within the ceramics and interrupted by the crack. The crack is detected automatically by detecting the difference of irradiants on each side of crack. In the experimental apparatus the laser spot is scanned with a polygon mirror and the distribution of irradiant on the ceramics is detected with a 2-divided photodiode. The high sensitivity for crack detection is obtained using a finite difference value of detected signal. Experimental results show that this crack detection technique detects the cracks of 0.5μm at an S/N ratio of 2 in the scanning process of laser spot.
It is important and effective to use angle information in profile measurement of ultra-precision surfaces. Very high sensitivity becomes necessary for angle displacement detection because of the high accuracy demand for this profile measurement. For this reason, development of high precision angle sensor is strongly needed. It has been reported that the noble performance of a newly developed angle sensor based on the principle of critical angle reflection. In order to improve the sensor stability and to approach 1/100 second accuracy, in this report, it has been added that a kind of compensator of thermal drift of the light source. The angle sensor consists of a semiconductor laser as the light source, an angle detector with two critical angle prisms, a compensator with two critical angle prisms and four photo-diodes. Two angle sensors of this kind with measuring range of 1800 s (arc) are developed, and are calibrated by the self-calibration method. It was found that the repeatability error of the mean sensitivity was improved to 0.01 %, and the linearity error was improved to 0.025 s (arc), moreover the error due to the thermal drift of the directional angle of the light source was reduced to be about 1/3 of original one.
The authors previously developed the CBP method to precisely measure the circular motion errors of a high precision CNC grinding machine, and investigated the effects of the move-ment conditions and NC parameters on the error trajectory. In the present study, the static accuracy tests are performed to assess the characteristics in motion of the test machine. The obtained data, such as straight motion errors and squareness errors, change with the measured position where a. measurement device is fixed. Then, a new method for transforming the data obtained at the measured position to that at the end of the wheel spindle is proposed. The error trajectory under the circular motion is computed by using the obtained data and the proposed transforming method. The estimated results are similar to the measured error trajectories. This implies that the proposed method is properly used for the transformation of the error vector and the prediction of the motion errors.
The light intensity diffracted from the superimposed dual transmission grating is sensitive to their relative lateral displacement. However, the light intensity as a function of lateral displacement generally deviates from the sinusoidal variation (signal distortion) and is affected by the air gap between them. In order to reduce the signal distortion, a new optical encoder using modulated pitch grating was proposed at 1st report. This paper presents the theory of the proposed encoder. The index scale has a modulated pitch grating, in which the distances between the grating slits vary a little. A photo-detector is assumed to be fixed on the rear surface of the index scale. The theoretical equation for the displacement signals and the basic design method of the modulated pitch grating are presented. The calculated results agree with experimental results.
Magnetic bearings haven't been used as precision bearings. Purpose of the research is to realize precision magnetic bearings. As the first step, this paper reports the results of the positioning performance of three kinds of non-contact supporting mechanisms using magnetic force; (1) a piezoelectric actuator (PEA) and permanent magnet type, (2) an electromagnet and permanent magnet type; and (3) an electromagnet type. In the first mechanism, the object is levitated by repulsion force of permanent magnets and driven by PEAs; in the second mechanism, the object is levitated the same as the first mechanism and driven by electromagnets; and in the third mechanism, the object is levitated and driven by the same electromagnets. In these mechanisms, high resolution sensor is used as a feedback sensor. The experimental results show that the positioning accuracy is 30nm for PEAs and permanent magnets, 15nm for electromagnets and permanent magnets, and 12nm for electromagnets alone and that the positioning accuracy depends on the sensor resolution.
The direct contour mapping (DCM) algorithm, which was proposed and developed by the authors, is effective for automated contour mapping around a peak of a solid body. For mapping of a solid body with multi peaks, the faculties for recognizing the shape of contour lines and for deducing the position of independent peaks should be needed. The DCM system in the present paper consists of a coordinate measuring machine (CMM), a personal computer (PC) and an engineering-workstation (EWS). With the DCM algorithm, the PC controls the CMM to measure a contour line of the solid body, then the shape of the measured contour line is represented by a chain code and sent to the EWS. The EWS analyzes the chain code data to recognize the shape of the contour line. The result of recognition is sent back to the PC, where the PC deduces the presentation and position of independent peaks. Experimental results of measurement for solid bodies having three and more peaks are shown.