Shigeo Ozono

Basic concept of feature-based metrology

Abstract In coordinate metrology, an associated feature (or the Gaussian associated feature) is calculated from an extracted feature that is determined by a measured data set of a CMM (coordinate measuring machine) on a real feature using the least squares method. This data processing flow, which is called ‘feature-based metrology’ disagrees with the data processing methods in profile metrology and length measurement. In this report, the basic concepts of feature-based metrology are discussed, such as feature modeling, the least squares method and the statistical estimation of the uncertainty of measurement. Theoretical analysis and simulations for feature-based metrology in statistical ways directly imply that the basic concepts and data processing methods in this report are useful in estimating the uncertainty of measurement in coordinate metrology.

Reliability on calibration of CMM

This paper presents a method which is able to describe the reliability of the parametric error as the calibration result of a CMM. The reliability range may provide uncertainty indication of the calibration. Emphasis is placed on description of expansion of the propagation of error on the linear system expressing the parametric errors of a CMM, and confirmation of the method through the simulation on the calibration performed only by linear displacement measurements.

3-D shape measurement by self-referenced pattern projection method

Abstract A shape measurement system using time sequential space encoding with multi-gray scale patterns has been developed [1] , [2] , [3] . However, some objects that have colored surfaces and unevenness of reflectivity could not be measured using these methods. Therefore the reference projection images are added to the system. By the reference projection method, the colored objects could be measured by comparing observed space encoding images with the reference images. However the number of projections increased. In this paper, the self-referenced pattern projection method is proposed. This method reduces the number of projections and it is able to measure objects under an illuminated environment and to measure colored objects. Using this system, the measuring space is encoded into n ! sub-spaces with n projections. If there is a commercial projector to encode space with high pixel-resolution and brightness in the near future. it would greatly benefit this method to be able to divide the measuring space into the most sub-spaces when it has the least pattern projections.

An instrument for manufacturing zone-plates by using a lathe

Abstract A laser writing system is developed in order to manufacture precise and inexpensive zone-plates. The zone-plates are a key component of an interferometer that measures shape error of spherical or aspherical mirrors on an ultrapecision lathe. The laser writer is mounted on the sliding table of the lathe. A glass plate coated with photoresist is attached to a chuck of the lathe and rotated. The zone-plate grating is written on the glass plate by a focused laser beam. Zone-plate writing is sped up by reducing the necessary number of computer instructions, causing no loss in the accuracy of the zone-plate. The accuracy of the zone-plate obtained by this inexpensive method is 0.1 μm and the same as that achieved by an electron beam writer.

Non-contact optical probing sensor — applying optical feedback effects in laser diodes

Abstract The possibility of a non-contact optical distance/displacement sensor, making use of optical intensity variations caused by optical feedback effects in laser diodes, was investigated. A compact sensor system and a simple signal processing technique were proposed to realise the sensor system. The experimental results indicated that the resolutions were of sub-mm order in distance measurements and about 40 nm in displacement measurements. The allowable maximum speed of displacement can be improved up to several cm/s. The influence of temperature variation on the measurement accuracy was discussed and the advanced sensing technique utilising a synthetic wavelength of laser diodes was proposed. These methods are applicable even to an object with rough surfaces.

High accuracy microdimension measurement system by using laser and CCD

Abstract A microdimension measurement system, using one-dimensional CCD as the sensor, was developed for measuring thin wire or slit. The principle of measurement is based on Fraunhofers diffraction. The system performs data processing of the diffraction pattern by using filtering and curve-fitting, by which the measuring accuracy was extremely improved. The measuring range of this system is from 20 μm to 200 μm. The total measuring uncertainty is less than 0.04 μm and the repeatability of measurements is less than 0.011 μm. Moreover, experimental results indicate that the system is applicable to vibrating objects as well.

3D profile measurement using a multi-gray scale compared with reference projections

Abstract Using a three dimensional measurement system with a gray code projection, this paper proposes a novel technique for improving the reliability of the space encoding method. This space encoding method can measure a colored object under a normal illuminated environment. The measurement space is separated into 256 sub-spaces by four gray level patterns. These patterns are projected by a liquid crystal display projector, and are observed by a CCD camera. When the measurement area is 160 mm × 130 mm, the measurement accuracy of this system is approximately 0.5 mm, and the standard deviation is 0.35 mm in a dark room environment and 0.39 mm in a normal illuminated environment. It is shown that this method can be used to measure a colored object by measuring a colored plaster figure in a dark room environment and under a normal illuminated environment.

Development of a Snake-like Robot

In spite of the wide theoretical capabilities they are attributed, the use of snake-like mobile robots is still limited, partly because the control of such systems is difficult, and requires a high computational cost, even in very simple situations. In this paper we described the design of a wheeled hyperredundant robot that can perform 3-dimensional movements. We also simulated a specific planar movement mode that requires no control of the joints. Both the mechanical and the control structures of the robot were thought as modular for reasons of robustness and convenience of development. The mechanical structure of each module was based on the use of two different mechanical joints: one powerful for the vertical rotation, which was connected with the wheels, and the other for horizontal rotation that could move freely when it was not controlled. This last feature enabled to simulate the considered planar movement. The modular control structure improves the robustness of the robot as it makes self-reconfiguration possible. Finally the simulation showed the fact that using such a planar mode is relevant and requires a few computational cost. Some trajectories of the movement of the robot were numerically investigated.

A New Path Planning Method For Mobile Robots Applicable To An Arbitrary Environment

This paper proposes a new path planning method for mobile robots applicable to an arbitrary environment. In this method, a new potential function is introduced and four motion governing forces are defined by using this potential function and the goal position. Mobile robots move according to the combined effects of the four forces. This method can be applied to an arbitrary environment and achieves a solution in a short time.

Geometric Calibration of CMM by Utilizing Spatial Coordinate Comparison. 1st Report. Design of Parametric Model and Its Simulation.

A series of papers presents a new calibration method particularly for up to a middle size CMM. The method is able to provide the 21 parametric errors only by performing the coordinate comparison. An automated calibration system for the production stage of CMMs is realized. The first report describes basic structure of the linear parameter model which establishes relation between spatial displacement deviation observed by the coordinate comparison and the linearly combined parametric error components of the CMM. A simulation on a simple guide way example with six independent freedoms is performed to verify functionality of the model. The result shows that 96 parameters expressing six parametric errors are possible to be handled simultaneously. It is confirmed that the parametric errors are estimated with sufficient resolution to apply the model to the calibration of CMMs.