[in Japanese]

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This paper describes an approach for estimating motion parameters of a rigid body utilizing three-dimensional (3-D) correspondence. 3-D positional information of object feature points, which is available for object representation and robot vision, is extracted by stereo matching at each instant. The correspondence between two 3-D point sets at sequential time instances is needed to find motion parameters, the best one is established using Hopfield neural network. On the basis of acquired information, two methods for motion estimation are proposed (1) in an incremental manner under a condition for smoothness of motion, and (2) in an iterative operation according to a Daugman-type linear network architecture. The results of applying these schema to a sequence of stereo images are presented.

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This development paper describes the optical measurement system of diametral dimension by parallel scanning of a laser beam. The measure is taken by counting the synchronous pulses with the scanning position of the beam. The pulse signal is generated with a linear scale composed of the optical slits at an equal space on the rotational scanning unit. Therefore a high-precision constant speed motor and fundamental optical components such as a scanning polygon mirror and an Fθ lens fall into disuse. Its compact size and omission of complicated electronic circuits for time-consuming calculation are also strong points of the developed measurement system.

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This paper deals with an integrated modeling system of machine tools for dynamic analysis and simulation. The structural elements of the machine tools are represented by a set of primitives with information about finite element meshes. An algorithm is newly proposed based on a concept called CBC (Coded Box Cell) substitution approach to match the finite element meshes at the interface of primitives with relative movements. The nodes on the boundary surfaces between the two adjacent primitives are automatically adjusted by referring to the information of the vertex label and the face label of the meshes. The results of case study show that the finite element model is adjusted dynamically and locally at the boundary of the table and the slider which is fed on the table. It is expected that the method proposed is quite effective to analyze the structural characteristics of machine tools under the moving conditions.

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An implementation method of STEP data exchange system is proposed based on a program generation method. Firstly, a formal specification of the data exchange process is derived from examining the data integrity during the data conversion. Using EXPRESS, the specification can be described in the form of a STEP application protocol, CAD data schema definition and data conversion functions, which is then translated to generate most of the system. In the system, STEP data input and output programs are prepared as generic. Only CAD data input and output programs are CAD system dependent and prepared separately. The data to be exchanged are input into data repository, then data integrity checking is performed. Data conversion is done for the data in the data repository and stored again after the data integrity checking after the conversion. The proposed method is an exact implementation of STEP standard and provides a system with high portability and flexibility.

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On the problem of robot path planning using a configuration space approach, since boundaries of obstacles in the configuration space are very complex, it is difficult to construct those boundaries by analytic methods. Therefore, most of the approach to find a safe path are using search strategies, for examples, the configuration space is devided into cells and interferences are checked in each cell. But for those search strategies, it is difficult to determine the existence of the safe paths. This paper describes the method that represents the obstacles as a CSG/B-Reps dual solid model in the configuration space, by deriving the boundaries of obstacles in the configuration space in an analytical way. Using that solid model, an existence of the safe paths is determined, and if so, one of the safe paths is also generated.

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In creep feed grinding, the grinding cracks are generated by heat. It has been known by experience that the grinding fluids influence on grinding cracks. Grinding fluids are generally used for cooling and lubrication. To evaluate the properties of grinding fluids, the temperature at the grinding point, cooling rate of work material and load carrying capacity of grinding fluids were checked. Finally it was clarified that a gentle slope of cooling could relieve the grinding cracks and high load carrying capacity of grinding fluid was not effective.

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In belt grinding, the amount of heat generated throughout the grinding process is basically less compared with that of the grinding wheel. However, when heavy grinding conditions are selected for obtaining high machining efficiency, the flatness error of the belt machined surface gets considerably larger than under normal conditions because of the high level of heat generation. Therefore, for reducing this flatness error, the depth of cut of the abrasive belt calculated by fuzzy inference was applied to the workpiece surface. In order to do this, the trace curves of abrasive belt on the workpiece surface were calculated by using fuzzy inference, rules of which were decided from simple models based on the basic grinding experiments. As a result, the accuracy of machined surfaces were improved significantly, and the propriety of applying this method for belt grinding was confirmed.

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As an application of diamond coating using oxyacetylene flame, coating on cutting inserts made of cemented carbides was attempted using a chamber at atmospheric pressure and four torches mounted therein. By igniting torches in the Chamber and shutting off out side air, secondary and harmful combustion flame was found to be eliminated and consequently the diamond coating using only primary combustion flame (acetylene feather) was possible even at normal ambient pressure. An application of the method to cutting inserts was then attempted, with a successful result in coating four corners of a cutting insert with diamond in as short a time as 40min. Further, evaluation of the cutting performance of the insert was carried out using an 18% Si-Al alloy as workmaterial, and the result showed that a good performance nearly equivalent to that of the diamond coated inserts prepared by hot filament CVD process was possible to obtain.

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Automatic monitoring of cutting process is one of the most important technologies for increasing the stability and the reliability of unmanned manufacturing system. In this study, the methods which use acoustic emission (AE) signals are proposed to monitor chatter vibration, tool wear and cutting edge breakage in the milling process. All experiments were conducted on an NC-vertical milling machine. The ball endmill cutter with 2 cutting edges and the square endmill cutter with 4 cutting edges were used. Using these equipment, the single-sensor monitoring system was constructed.

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In grinding operations, one of the most important problems is to determine the tool life of a grinding wheel accurately. Frequent dressing wastes not only time but also the abrasive materials, which becomes crucial when an expensive tool such as a CBN wheel is used. Grinding with a worn wheel causes the workpiece surface roughness to increase and often results in the occurrence of such troubles as chatter vibration. However, highly reliable techniques to monitor the tool life of a grinding wheel have not been established yet, and the wheel life is, in most cases, determined by human operators based on their observations and expertise. In this study, the monitoring method using an acoustic emission (AE) sensor is proposed to define the wheel tool life in the cylindrical grinding process. The contact detection between the wheel and the dresser, as well as the evaluation of the grain sharpness, are attained by monitoring the amplitude level of the AE signal. The chatter vibration is, on the other hand, detected by observing the power spectrum of the rectified AE signal, and well recognized by means of the neural network.

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This paper deals with the lapping characteristics for crystallographic orientation of single crystal diamond. The rough diamonds were lapped by cast iron lap as well as steel lap and diamond wheels. The lapping removal depth, lapping force ratio (tangential force / normal force) and lapping temperature for lapping direction on the typical three planes were measured. Experimental results are as follows : the relationship between lapping removal depth and lapping force ratio was devided into the following two trend. In the lapping by cast iron lap and steel lap, at the easy lapping direction (i.e. {110}, <100>) lapping force ratio was small and lapping temperature was low, at the hard lapping direction ({110}, <110>) the former value was large and the latter was high respectively. On the other hand, in the lapping by diamond wheel, at the easy and hard lapping direction these two values changed conversely in the tendency of the cases by cast iron and steel lap.

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This paper describes the relation between the right angle error and the accuracy of a convex spherical shape on works when using lip type grinding wheels. The right angle error between a work axis and an inner cone surface of a lip type grinding wheel brings the effect upon the spherical shape on the work, and deforms its shape to aspherical. The expressions of this aspherical shape are formulated, and the correlative equations between the right angle error values and the patterns obtained from interference fringes of this aspherical shape are also made out. The experiment is performed for the optical glass rod work (φ10×L100mm) using a lip type grinding wheel filled up with 7 μm diamonds. Following conclusions are obtained : (1) When a work axis and an inner cone surface of a lip type grinding wheel are not at right angles to each other, the spherical shape obtained on the work deforms to aspherical having a cone shape at the center, and having other spherical shape (its center is not on the work axis) at the peripheral part of the surface of revolution. (2) As a work axis inclines toward the opened side of a grinding wheel and its value Δγ is 7.0×10^-3 rad, the peak shape is formed at the center and about 16 pieces of interference fringe appear on the work in agreement with the calculated results on the experiment.

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The bending strength deterioration of sintered TiB₂ (electrical conductive ceramics) produced by electrical discharge machining (EDM) and its recovering technology have been studied. The strength deterioration of EDMed ceramics occurs under the conditions of high peak current with long pulse duration. Roughness and cracks of the EDMed surface are considered to cause the deterioration. Chemical etching and electro-chemical etching onto the EDMed surface of the ceramics were carried out in order to recover the strength. The strength recovered conspicuously by removing the EDMed surface layer with several tens micrometers. Finish EDM with silicon powder suspended working fluid is expected to be effective in avoiding the strength deterioration for the reason of discharge dispersion.

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Fast and fine position control of an ultrasonic motor is generally difficult because its rotational speed is nonlinear to voltage, frequency or phase shift input. This paper shows both theoretically and experimentally that the motor has an approximate first-order transfer function between phase shift input and rotational speed output in the case of coarse motion to a command position. This paper also shows experimentally that the rotor moves finely and intermittently in the neighborhood of the command position. A linear position control system which applies integral control action was developed. A fast response of about 50ms and fairly high positioning accuracy up to a rotary encoder resolution were both realized.

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A coordinate measurement method is developed which is based on optical triangulation and uses a spherical mirror as a target. Each of the three axes employs a slit-ray laser scanner and a photo-detector to detect the direction of the regular reflection from the target mirror. Since this method detects only the center of curvature of the mirror, it is suitable when the attitude of the target changes, e.g. a robot arm. Moreover, the use of the spherical mirror allows precise calibration and easy set up. To demonstrate this measurement method, coordinate values in one-dimension were measured at various distances. In this paper, the results form this one dimensional test are presented. The proposed measurement method was shown to be feasible through this experiment. The small beam size and small divergent angle of the light source produced high accuracy, while the detector size was found to have little effect on the accuracy. The measuring accuracy of the system was evaluated to be 20 μm at a distance of 750 mm.

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Fringe counting techniques are often used in modern laser interferometers for measuring displacement. These interferometers are essentially integrating devices, where the displacement is derived from an accumulated fringe count, that is, they measure travel rather than static displacement. If the interferometer optical paths are interruptedduring a measurement cycle, the reference for the instrument is lost and accuracy suffers. In this paper, a holographic technique whereby displacement is measured by analyzing a fringe pattern localized at infinity which is equivalent to Haidinger or Brewster fringes in conventional interferometry is described. The phase distribution of the fringe pattern is measured to high accurcy using phase-stepping interferometry, and then analyzed by computer. Using this technique, in-plane displacements could be measured with an accurancy of about 0.2μm whilst the accuracy for out of plane displacements was about 2μm.

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This paper presents a new method to feed a table smoothly over a long stroke by utilizing deformation of piezoelectric elements, which is named “Walking Drive.” The principle of the method developed is similar to walking motion of animals such as human beings, dogs, spiders, centipedes and so on. The table is fed smoothly over a long stroke with the combinations of clamping and feeding motions of piezoelectric actuators controlled in synchronization despite the fact that the stroke of each piezoelectric element is limited. A precision feed system based on the walking drive was developed using a ceramic air slide, and the feasibility of the drive mechanism was confirmed.

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