Perpendicularity measurement is very important in machine assembly and calibration. Axis perpendicularity error often
contributes much more to the total error than the linear positioning and straightness errors. This paper presents two new
non-contact methods for measuring axis perpendicularity using vision system. In general a perpendicular master and a
dial gauge are used to measure the axis perpendicularity. We can obtain the axis perpendicularity by measuring
differences from the master. Therefore, its accuracy depends on the accuracy of perpendicular master. The accuracy of
the perpendicular master is therefore extremely important and it is impossible that the accuracy of a perpendicularity
measurement is superior to the accuracy of the perpendicular master. This paper proposes two new methods that can
measure axis perpendicularity without using a perpendicular master. Absolute axis perpendicularity measurement can be
achieved by vision system. The feasibility of our developed measurement methods are confirmed by several
We present a high-precision fringe pattern projection technique based on a novel 4D hypersurface calibration method, and its application to on-machine measurement of raw-stocks in die-making industry. Our fringe pattern projection technique has the following feature. In the calibration stage, coordinates (x, y) of a CCD image sensor correspond uniquely, for every calibration plane with height Z<sub>i</sub> (i=1,..,n), to a phase φ of a projected fringe pattern, and coordinates (X , Y) of a machine tool. These relationships are converted to hypersurfaces in 4D spaces of (x, y, Z, φ), (x, y, Z, X), and (x, y, Z, Y), which are considered to be a sort of function. Using these hypersurfaces, a measured data of (x, y, φ) is transformed to machine tool coordinates (X, Y, Z). Our hypersurface calibration method is expected to minimize systematic errors, because it inputs an observed data (x, y, φ) into precise interpolation functions created using actual measurement data, and accordingly systematic errors are cancelled. The repeatability, systematic errors, and random errors obtained from the experiment show that our measurement system has a potential for highly accurate non-contact 3D shape measurement.
Stereolithography is one of the Rapid Prototyping and manufacturing technologies which enable to fabricate three dimensional structures easily, quickly and automatically from computer-aided design (CAD) drawing. But it is much difficult to realize microfabrication quickly and accurately using conventional laser-scanning stereolithography due to thick layer of lamination and long time of fabrication. In order to overcome these difficulties, the liquid crystal display (LCD) microstereolthography has been developed in our laboratory, which enable microfabrication of a complete layer by only one irradiation, at high speed as well as high accuracy by continuous laminating of thin layers using the LCD as a live-motion mask. We performed the fundamental experiments to fabricate general 3D micro structure consisting of the overhanging shape using the LCD live-motion mask microstereolithography, and tried to fabricate a microspring with several ten micrometers size as one example.
Conference Committee Involvement (2)
Optomechatronic Sensors and Instrumentation II
3 October 2006 | Boston, Massachusetts, United States