A dual-axis numerical control rotary table is designed in this article to calibrate a dual-axis tilt sensor. The device comprises a swing axis and a rotating axis, which are used to produce tilts in two perpendicular directions. To achieve precise control of the motion mechanism and enhance positioning accuracy, the time-grating angular displacement sensors have been adopted as the feedback and measurement components in both axes of the device. The experimental results indicate that the error of the swing axis of this calibration device is ±1.5 arcsec, while the error of the rotation axis is ±1.0 arcsec, with a repeatability of less than 0.5 arcsec, which is suitable for the calibration of the majority of dual-axis tilt sensors.
In this context, the present research work aims at studying and developing an innovative approach for automated sampling path model for large simple regularly conical workpiece, which could provide designers easily and rapidly taken. Therefore, our attention is focused on 3D geometric relationships between neighboring end points of edge features of workpiece. An algorithm is proposed to guide the scanner device and move it along the main direction of the plane containing the projection of the next critical end point with the use of geometric properties of previously extracted end points. Thus, an appropriate 3D circular-arc scanning path is on-line automatically yielded step by step by an orderly collection of local connected end points. Finally, a series of experiment on typical conical workpieces are carried out to demonstrate the automated path planning technique and the final sampling quality.
This article presents a novel automated measurement prototype for 3D geometry of mobile and large-scale conical workpiece, manipulated through two independent robot platforms that placed on its two sides with laser scanner and motorized linear stage. First, with point cloud that covers end point provided by laser scanner. Then, modeling and identification of end point of workpiece is established based on height variations in its nearest neighborhood with respect to virtual measurement datum plane, which is step-by-step derivatively generated according to initial datum point in an online virtual inspection environment. Next, the current geometry-relations between neighboring end points can be subsequently used to guide the laser scanner for high precision sampling surface area incorporating an automatic simple module. Moreover, both orientation and position geometrical relationships of the corresponding features on the fitting circles are analyzed too. Details preliminary experimental tests were performed to verify the measuring accuracy of this method.
Laser interference system has been extensively applied in high-precision geometric metrology benefit from the advantages of high accuracy, high resolution and stability in linear displacement measurement. In this paper, we present a novel and compact mechanical structure to realize the conversion between angular and linear displacement, so that the slight angular displacement can be enlarged and obtained by using the characteristics of high-precision linear displacement measurement of laser interference system. A series of experiments are carried out on this device, the conversion ratio of angular and linear displacement we achieved is 5.76 arcsec/ μm, which is determined by the transmission ratio of the worm gear pair and the pitch of the ball screw. By comparing the measured angular values with 23 reference values distributed on the whole circumference, the maximum original error of angular displacement measurement in this system without correction or compensation is ± 25 arcsec and the resolution is 0.6 arcsec.
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