[in Japanese]

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[in Japanese]

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The visual inspection tool for detecting uneven area defects that appear in a screen of an LCD display by image processing was developed. By differential processing in multiple resolute images that are generated from an original image, various uneven area defects that have different sizes and shapes are detected. Evaluating factors that influence a human visual sensitivity about uneven area defects is experimented. As the experimental result, it was found that various factors about uneven area defects influence a visual conspicuous ratio. Through the inspection, various feature data related to a visual conspicuous ratio about uneven area defects were output.

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Since plastic models made by laser lithography have ledges on their surfaces, reducing of ledges is required to use them as master models for jewellery. To improve the quality of plastic models, a diagonal irradiation method has been presented. The diagonal irradiation method reduces surface roughness by means of heaping up diagonal shape solidified by diagonal laser irradiation. The theoretical analysis has clarified the relationship between irradiation angle and solidified profiles in the 1st report. In this paper, an algorithm which makes plastic models from geometrical models is presented. This algorithm has been used by an experimental system to produce rings. The result shows that the accuracy of these rings is improved by the diagonal irradiation method.

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In solid modeling systems, Boolean set operations are very sensitive to numerical errors. These problems can be solved by adopting the variable length integer computations based on the extended 4×4 determinant method. The efficiency of these computations, however, goes to worse as the lengths of integers increase. In practice, many geometric algorithms such as Boolean set operations can be reduced to detecting the signs of determinants. By using the adaptive sign detection method, the signs can be detected in nearly constant time for any length of integer. In this paper, a method is proposed that improves the efficiency of the adaptive sign detection. All of internal numerical computations with this method are processed as the floating point number arithmetic by using an FPU (Floating point Processing Unit). It is remarkable that this method never outputs wrong results although floating point computations are performed. The performance experiment shows that the new sign detection method is about 15 times faster than the old one.

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This paper describes piezoelectric force sensor of a placement system for surface mount devices. Electric charge of the piezoelectric sensor was converted into voltage signal with charge amplifier. And then, in the developed method, a satisfactory measurement of the chip placement force was accomplished by compensation for the voltage signal. This compensation was based on an integral compensation for a transfer function of the charge amplifier. As a result, an effectuality of piezoelectric devices for mount force sensor was confirmed. And the endurance tests were put into practice. The result of the test was that well endurance characteristic was confirmed.

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A robot system has been developed in which four SCARA type arms move simultaneously in a single working area. To avoid collision, the “occupied quadrant” algorithm is proposed. Every quadrant is assigned for each arm as the tool center point is located at the corner of the quadrant, and the working points are assigned for each arm as there is non-egative margin between the quadrants. Together with the linear interpolation in Cartesian space and with simultaneous motion control for the all arms, high speed collision-free movement is obtained. The algorithm was proved with the practical prototype machine. Tact time was proved to be less than 0.35 second.

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In this paper, it is demonstrated that object shape is detected easily by scanning with a coaxial laser beam. The coaxial laser beam consists of the He-Ne laser and laser diode beams which are different in diameter. The lights scattered from the object are detected individually through the respective optical filters. The edge position of the object is obtained from the difference between the two light intensities. The image of the object edge is obtained instantaneously only by scanning with the laser beam since the object edge is enhanced in a manner similar to the biological receptive field. The edge enhancement is also explained theoretically.

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As it is difficult to explain a high power laser welding process because of its complicated phenomena, a simple model rarely contains enough information to explain welded shape or penetration properties. In this report, by arranging several welding data which were obtained using several high power CO₂ laser resonators, a simple equation to assume the penetration depth has been considered. Also, high power laser welding phenomena have been tried to explain by using a conventional thermal conduction theory. According to the experimental data, at least 300 J/cm of input energy is needed to make a keyhole. It was also found that penetration depth has a linear relationship with power, but there is a complicated correlation between spot size and speed. A simple equation to explain the penetration depth was obtained by several experimental data as a function of power, spot size, and speed. Also, in order to explain a keyhole welding, it was assumed that a keyhole diameter equals to a focused spot size, 8 line heat sources exist on the circumference of a keyhole and that to heat up on the metal surface by plasma of which energy is similar to a Gaussian heat source. This combination modeling to show the penetration shape showed a fairly good agreement with experimental data.

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A calibration method for displacement sensors is proposed, in which linearity errors over a calibrating range can be approximately known every coarse interval with an equal nominal output width. The method has a characteristic of a kind of the self-inspection technique in the sense that except input references corresponding to the interval, whose actual values are unknown, special references for calibration are not needed. Two kinds of electronic micrometer being taken up as objects of calibration, experiments are carried out to examine the method in a range of 300 μm under some conditions. Comparisons between experimental results by this method and other ones and an examination of calibration errors are also performed. Linearity errors obtained in all cases show good agreements within about 0.1 μm. This method is considered to have a possibility to the purpose.

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In order to establish a delta operator technique in fixed-point arithmetic, the first report proposed a modified delta operator newly and verified its availability for the first-order systems. The second report tried to apply this operator to the nth-order systems. Furthermore, a new error reduction method named Variable Modulation Method (V.M.M.) was proposed. In the present paper, it is aimed to apply V.M.M. to an optimal control system. First, it is shown that the equivalence between a shift model and a delta model, which was proved in the first report by the help of transfer function, can be kept in a state-space equation too. Following this result, the modified delta model based on state-space equation was derived. Next, the design procedure of an optimal control system based on modified delta model with V.M.M. is described generally. Having applied this procedure to the optimal controlling of DC motor, the availability of V.M.M. was made clear for the cases of smaller word length, that could not be realized if the algorithm was represented by the conventional shift or delta operators.

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The positioning and rotational accuracies of ordinary magnetic bearings are not high enough because of low accuracies of displacement sensors. To improve their accuracies, there are two possible methods; use of expensive and precision sensors, or sensorless control by using an observer. In this report, first the mechanism which had electromagnetic characteristics suitable for sensorless displacement measurement by an observer was introduced. Then an observer was designed according to the dynamic model of the mechanism identified through measured frequency characteristics. In order to realize accurate displacement estimation, the dynamic model of the mechanisms was modified so that the estimated displacement coincided with the output of a precision sensor. The experimental results show that the resolution of estimated displacement and sensorless positioning were 150nm and 200nm respectively and the positioning range was above ±100μm by using the modified observer.

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Inverse kinematics problem is important for the robotics control tasks. However, this field of kinematics is very complicated. Generally the inverse kinematics problem appears from the fact that inverse mapping of functions which have many variables should be made. This report studied on the inverse kinematics problem of 3R robot. In the 1st report the solutions were classified by the part of the Joint space partitioned by singular space. It is sufficient to classify the solutions in the case single solution to the world point exists in the part. But if plural solutions exist it is insufficient to classify according to the partition. In this study the condition of the plural inverse kinematics solutions existence are analysed. A new analysis approach named Joint Space Cutting method is presented. In the Joint Space Cutting, many cutting sections are formed and every point of the world coordinate system intersect to the mapping image of the sections. But the mapping image of the section planes are the rotation of the image of a section mapping. So, to analyse the condition of the plurality of the inverse kinematics solution, lead us to solve the intersection point number of the curves formed by the intersection of the image surface and the plane pallarel to x-y plane. The plural maps in the Joint space are also presented.

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A new application of giant magnetostrictive materials (GMM) is proposed. In most application using GMM, transduction from magnetic energy to mechanical energy is utilized. As an interesting potential application, unlike the conventional ones, a reverse phenomenon of GMM is applied to an electric generator. Longitudinal oscillations of GMM rod give rise to a varying flux which induces a current in the coil surrounding the rod. This report deals with a fabrication of electric generator, accompanied by some experiments for generation and storage of electric energy. The experimental results imply that this method may be utilized for the effective use of the mechanical energy which will be wasted otherwise such as wind, running water, mechanical vibration, and so on.

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This paper deals with a development of CAM system for rough cutting of metal dies and molds. A number of rough cutting methods have been proposed and developed to improve machining efficiency, however, there are remained functions to be considered. To solve remained functions, in this study, a new rough cutting system is developed. Developed system consists of two operational processes. In the first process, blank material is divided into several layers having thickness corresponding to available maximum cut of depth. Each layer is subdivided into domains possible to machine by tool path with linear motion. In the second process, contour line tool path is generated for machining unremovable parts in the first process. In this time, to reduce a sudden change of cutting force due to affect tool life, offset surface is generated as constantly keeping volume to be machined. Tool path simulations and practical machining tests by using developed system show : (1) total amount of NC data can be reduced for conventional rough cutting, and (2) both high efficiency machining and extension of tool life can be realized by applying linear motion and reducing change of cutting force.

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This paper treats a kind of simple model identification method using the fuzzy ID3 and trapezoidal membership function of fuzzy sets, and its application to the rules generation for the process distribution in grinding. The rules are given in the form of decision tree through the fuzzy ID3, in which four attributes, that is total depth of cut, surface finish, dimension accuracy and contours accuracy. The rules are used as the production rules in expert system for grinding with high precision machining center. A case study is performed for the demonstration of the proposed algorithms, using a part sample.

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As multiple degrees of freedom (DOF), high accuracy and high response are required for an end effector for electrical discharge machining with a scanning motion (scanning EDM), a parallel mechanism is applied to it. This mechanism consists of a base plate, a stage, a constraint link and three links connected in parallel to the base plate and the stage. Each inchworm mechanism acts as one of the links. This mechanism has 3 DOF (θ, φ, z). The position and inclination of the stage are controlled by adjusting the length of three links cooperatively. This mechanism is driven by the combination of the step mode and the linear mode. The stage is driven by the normal sequence of the inchworm mechanism in the step mode, and by changing the length of the drivers of the inchworm mechanisms in the linear mode. The position of the stage is controlled by the step mode for large range of displacement, and by the linear mode for fine steps with high response. The electrode feeding is mainly controlled by the linear mode during the scanning EDM. The positioning accuracy in the step mode is 30 !AM in height and 0.04° in inclination. The, frequency response of the stage in the linear mode is up to 200 Hz. Holes and grooves can be machined by the scanning EDM with this end effector.

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Ceramic balls are expected to become useful for tougher bearings than conventional ones. However, the conventional ball lapping method which uses a couple of flat and V-groove lapping plates, needs so long machining time. In present paper, efficient lapping method of silicon nitride balls has been proposed. In this method, it is designed that V-groove lapping plate is separated into two parts and three plates are able to rotate independently. This lapping equipment enables the spin angle θ of ball to control from 0° to 90° It is found from the experiments that the spin angle θ of ball has great influence to lapping of silicon nitride one. Stock removal rate increases gradually with increase of the spin angle θ and surface roughness decreases considerably with increase of it in which lapping mode varies from the satin finished surface to scratched one. Experiments indicate that degree of the reduction of deviated diameter of ball from ideal one is dependent both upon the rotational speed and the spin angle.

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