Papers by Keyword: Precision Measurement

Abstract: Geometric dimensioning measurement is a very important application in metrology. In this paper, we focus on the geometric dimensioning automatic detection of tubular member based on the laser displacement sensor. An automatic detection system of tubular member is designed using line laser scanning principle. The system includes base, swivel table, servo motor, motor driver, servo pack, motor controller, laser displacement sensor, data acquisition card, and computer. The system first gathers the displacement information by laser displacement sensor, then performs coordinate transformation and three dimension reconstruction of the tubular member. The external diameter and the roundness error can also be measured. The experimental results show that the geometric dimensioning parameters measurement is effective and accurate using this method.

Abstract: Digital Speckle Pattern Interferometry ( DSPI for short ) method has become one of the most practical worthy techniques for speckle measuring methods with the high-speed development of optic-electronical technique, image processing technology and electronic computer technology. There is a lot of advantages about it, such as uncomplicated operation, non-contacting, advanced automatic level, measurement on-line and extensive using. In this thesis, the displacement variation of the induced strain field for driving by piezoelectric ceramics can be measured by using this method. Thus we can come to a conclusion that digital speckle pattern interferometry is a new measuring method for extracting small-signal. It also provides a powerfully theoretical and experimental platform for study of automated, full-field, high-precision and nondestructive measurement.

Abstract: As the most important error source in the heterodyne interferometer, the nonlinearity errors reduce the measurement accuracy in the nanometric or picometric measurement. This survey states both the definition of nonlinearity errors and the cause of the errors. Moreover, two kinds of methods for detection and compensation of the nonlinearity errors are also discussed respectively in this paper.

Abstract: Absolute measuring principle of the high-speed rail was introduced to the measurement of existing speed rail. The line parameter reconstruction and long-wave smooth management is implemented. CPIII control points are laid along existing speed rail. Using the track fine-adjustment instrument, the center geodetic coordinates of midline of track were measured precisely. By least squares fitting method, parameters of straight line between curves was calculated. Plane curve were reconstructed based on measured geodetic coordinates of the continuous rail. The optimization results were used for the theoretical basis, and smoothness of 30 meters chord and 300 meters chord of rail were analyzed, and adjustments of plane curve were calculated to meet the long-wave smooth of rail.

Abstract: A strain-gauge-type precision displacement sensor, which is developed for a usage of micro-XY stage, is described in this paper. A thin-film strain-gauge element, which is made by Cr-N alloy, is directly fabricated on the base of the strain gauge. The direct fabrication and using the Cr-N element are expected to achieve higher sensitivity for displacement detection and better stability against the change of ambient temperature. In this study, several designs of the thin-film strain gauge, including both of two-gauge-type and four-gauge-type, are prepared to compare sensor performances such as sensitivity, stability and so on. The designed patterns of the strain-gauge element are directly fabricated on zirconia plates by using photolithography processes. The fabricated strain gauges are then evaluated as precision displacement sensors. At first, stability of the fabricated Cr-N strain-gauge-type displacement sensor was confirmed by comparing with the one made by a conventional strain gauge. Resolution of the fabricated Cr-N strain-gauge-type displacement sensors was then evaluated by comparing with a commercially-available laser displacement sensor, while giving sub-micrometer-order deformation to the strain-gauge-type displacement sensor. Details of the design, fabrication and evaluation results of the Cr-N strain-gauge-type displacement sensor are described.

Abstract: The accuracy of precision measurement is an essential requirement for precision positioning. This paper presents a new precision measurement method by combining the uniqueness analysis of laser speckle patterns (LSPs) and the template matching algorithm. In this paper, an invariant speckle capturing device and template matching criteria are developed. Experimental results have shown that LSPs can demonstrate different unique and invariant properties even though they are captured from the same material but different samples. Also, accurate direction and displacement information of moving LSPs can be obtained in real-time. Therefore, this merit can provide the potential of speckle pattern analysis for applications of precision positioning in the future.

Abstract: This paper introduces a method of measuring the gear chamfering profile based on laser sensor and machine vision through two grades. After machine vision part uses a vision sensor to get the location information of gear teeth at first. Then the laser sensor is moved to the position of gear teeth and takes the measurement of gear chamfering profile precisely.

Abstract: The positioning measurement of spatial curved surface steel structure project is a key link in construction process. How to measure position fast and precisely is an important problem concerned by steel structure project field. Taking actual project as an example, this article studied precision construction measurement technology in curved surface steel structure project, put forward resemble-leveling method elevation measurement, and naturalization lofting method which is based on spatial linear equation. This article has important guiding significance to precise position measurement of curved surface steel structure project and to construction control.

Abstract: To solve the critical problem of large gear deviation on-machine: angle displacement measurement that is how to get signal acquisition and accuracy analysis of angle displacement. A new measuring method is proposed, which applies the dividing mechanism (it is composed of friction disc and circular grating) to ensure index and pick up signal of gear corner correctly and strictly according to the principle of angular displacement measurement. Furthermore, the main error which affects measurement accuracy is analyzed, and accuracy is analyzed with geometrical theory such as Fourier series and error synthesis principle etc. The experimental results indicate that angel dividing and signal samplings are easier and more efficient by the dividing mechanism, furthermore, the accuracy is in the range of total error that is permitted by verification, and the mechanism can also meet the requirement of high accuracy, so the method is significance that assessing transmission accuracy of involutes gear.

Abstract: A method for reducing the size and cost of optical system for precision measurement based on the Levitation Mass Method (LMM) is proposed. In the LMM, a mass levitated using a pneumatic linear bearing with sufficiently small friction is made to collide with the object being tested. The velocity and acceleration of the mass are measured using a compact optical interferometer. The size of the optical system can be drastically reduced by using a planar lightwave circuit (PLC), in which several optical elements are arranged on a planar surface of a silica or semiconductor substrate. Several applications of the PLC to precision measurement will be discussed.