A vision measurement model of laser displacement sensor and its calibration method

This template explains and demonstrates how to design a measurement system based on the size of the linear structured light vision, the system could works at realized the high precision and fast measurement of the size of mechanical parts, and accurate calibration of the system. First of all, this paper set up the experimental platform based on linear structured light vision measurement. Secondly, this paper established a system of measurement model, and puts forward a new method of calibration of structured light sensor and set up the mathematical model of sensor calibration. This calibration method only need to use some gage blocks of high precision as the target, the target position need not have a strict requirements, and the solving process will be more convenient, much easier to field use and maintenance. Finally, measuring accuracy on the system by gage blocks with high precision is verified, the experiment shows that measurement accuracy within 0.050 mmin the depth of 0-80 - mm range. This system can satisfy the demands of precision testing of most industrial parts .with its simple calibration process and high precision, it is suitable for the structured light vision calibration.

Download Full-text

A Study of 3d Coordinate Measuring Based on Binocular Stereo Vision

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.740.531 ◽

2015 ◽

Vol 740 ◽

pp. 531-534 ◽

Cited By ~ 3

Author(s):

Tao He ◽

Jiu Yin Chen ◽

Xiang Hu ◽

Xian Wang

Keyword(s):

Machine Vision ◽

Stereo Vision ◽

Calibration Method ◽

Measurement Model ◽

Vision Measurement ◽

Model Based ◽

Binocular Stereo Vision ◽

Binocular Stereo ◽

Stereo Vision Measurement

It is important to obtain the 3d coordinate in the field of measuring. How accurate, fast, convenient to obtain the 3d coordinate affects the accuracy and reliability of measurement directly. Through studying the basic theories of machine vision this paper focus on the study of a stereo vision measurement model based on the intersecting axis. In view of the parameters in the model of binocular stereo vision, this paper uses the Zhang Zhengyou calibration method to calibrate the system of Stereo vision. In order to test the accuracy of the system, this paper measures the distance of two standard circular. Finally, the machining experiment validates the proposed method.

Download Full-text

Measurement of Cutting Edge Width of a Rotary Cutting Tool by Using a Laser Displacement Sensor

International Journal of Automation Technology ◽

10.20965/ijat.2014.p0028 ◽

2014 ◽

Vol 8 (1) ◽

pp. 28-33 ◽

Cited By ~ 5

Author(s):

So Ito ◽

◽

Sho Sekine ◽

Yuki Shimizu ◽

Wei Gao ◽

...

Keyword(s):

Light Intensity ◽

Cutting Tool ◽

Calibration Method ◽

Laser Spot ◽

Displacement Sensor ◽

Laser Displacement Sensor ◽

Spot Diameter ◽

Reflected Light ◽

Tool Edge ◽

Laser Spot Diameter

This paper introduces the widthmeasurement of a cutting tool edge by utilizing a laser triangulation displacement sensor. By using the reflected light intensity of the laser displacement sensor, micrometric edge width which is smaller than the diameter of the laser beam spot can be measured. With regard to the quantitative evaluation of the laser spot diameter, a calibration method of the laser spot diameter is achieved by using the pin-gauges. The diameter of the laser spot is obtained by using the pin-gauges, and the relationship between the reflected light intensity and the diameter of the pin-gauges are investigated. The width of the cutting tool edge is measured by the calibrated laser spot diameter, and then the reproducibility is evaluated.

Download Full-text

Turning Dynamics: Part 1 — Experimental Analysis

Volume 4: Dynamics, Control and Uncertainty, Parts A and B ◽

10.1115/imece2012-87933 ◽

2012 ◽

Author(s):

Eric B. Halfmann ◽

C. Steve Suh ◽

N. P. Hung

Keyword(s):

Instantaneous Frequency ◽

Period Doubling ◽

Displacement Sensor ◽

Laser Displacement Sensor ◽

Turning Process ◽

Time Frequency ◽

Spectral Components ◽

Tool Vibrations ◽

Exact Moment ◽

The Stability

The workpiece and tool vibrations in a lathe are experimentally studied to establish improved understanding of cutting dynamics that would support efforts in exceeding the current limits of the turning process. A Keyence laser displacement sensor is employed to monitor the workpiece and tool vibrations during chatter-free and chatter cutting. A procedure is developed that utilizes instantaneous frequency (IF) to identify the modes related to measurement noise and those innate of the cutting process. Instantaneous frequency is shown to thoroughly characterize the underlying turning dynamics and identify the exact moment in time when chatter fully developed. That IF provides the needed resolution for identifying the onset of chatter suggests that the stability of the process should be monitored in the time-frequency domain to effectively detect and characterize machining instability. It is determined that for the cutting tests performed chatters of the workpiece and tool are associated with the changing of the spectral components and more specifically period-doubling bifurcation. The analysis presented provides a view of the underlying dynamics of the lathe process which has not been experimentally observed before.

Download Full-text

Vibration Test of Titanium Alloy Pipes

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.184-185.701 ◽

2012 ◽

Vol 184-185 ◽

pp. 701-706

Author(s):

Ming Xing Qiu ◽

Chuang Shao ◽

Yong Zhou ◽

Li Hua Yue

Keyword(s):

Titanium Alloy ◽

Failure Criteria ◽

Fatigue Tests ◽

Test Method ◽

Displacement Sensor ◽

Laser Displacement Sensor ◽

New Findings ◽

Vibration Fatigue ◽

Welded Pipe ◽

Test Result

In order to determine the fatigue limits of two kinds of titanium alloy pipes connected by welding and rolling, fatigue tests were carried out by the Aero-Criterion which gives vibration fatigue test method and failure criteria. A laser-displacement-sensor was used at the free end and a strain-gauge at the root of the pipe specimen. The test result shows that the fatigue limit of the welded pipe is higher than the rolled one. In the end some new findings are listed according to the test.

Download Full-text

In-Process Visualisation for Deformation Monitoring and Analysis of Sheet Metal Forming Processes

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.677.384 ◽

2013 ◽

Vol 677 ◽

pp. 384-387 ◽

Cited By ~ 1

Author(s):

Wai Kei Ricky Kot ◽

Luen Chow Chan

Keyword(s):

Sheet Metal ◽

Sheet Metal Forming ◽

Deep Drawing ◽

Metal Forming ◽

Deformation Process ◽

Deformation Monitoring ◽

Displacement Sensor ◽

Laser Displacement Sensor ◽

Profile Data ◽

Profile Change

In this paper, a visualisation system will be discussed that can be used to capture the deformation profile of the sheet blank during sheet metal forming processes, such as deep drawing and shape forming. The visualisation system utilizes a 2D laser displacement sensor for deformation profile acquisition. The sensor is embedded in the die and the laser propagates through the die to detect the profile change of the specimen concealed in the die during operation. The captured profile data will be collected, manipulated and transferred to a monitor for display via a controller. This visualisation of the deformation profile will provide engineers and researchers with an intuitive means of analysing and diagnosing the deformation process during sheet metal forming.

Download Full-text

Profile Measurement of a Curved Workpiece by the Fuzzy Control of Sensor Positioning

10.1115/imece1999-0721 ◽

1999 ◽

Author(s):

Masatake Shiraishi ◽

Gongjun Yang

Keyword(s):

Fuzzy Control ◽

Control Algorithm ◽

Experimental Results ◽

Measuring System ◽

Displacement Sensor ◽

Profile Measurement ◽

Laser Displacement Sensor ◽

Inclination Angles ◽

Fuzzy Control Algorithm ◽

Sensor Positioning

Abstract A laser displacement sensor which has a resolution of 0.5 μm was used to determine the measurement of a curved workpiece profile in turning. This sensor is attached to a specially designed stage and is operated by three motors which are controlled by a fuzzy control algorithm. The experimental results show that the measuring system can be applied to workpieces having inclination angles of up to around 45°. The proposed measuring system has a practical measuring accuracy to within ten micrometers.

Download Full-text

High-Accuracy Calibration Based on Linearity Adjustment for Eddy Current Displacement Sensor

Sensors ◽

10.3390/s18092842 ◽

2018 ◽

Vol 18 (9) ◽

pp. 2842 ◽

Cited By ~ 4

Author(s):

Wei Liu ◽

Bing Liang ◽

Zhenyuan Jia ◽

Di Feng ◽

Xintong Jiang ◽

...

Keyword(s):

Eddy Current ◽

Measurement Accuracy ◽

Characteristic Curve ◽

Calibration Method ◽

High Accuracy ◽

Output Characteristic ◽

Displacement Sensor ◽

Support Vector ◽

Displacement Sensors ◽

Calibration Accuracy

High precision position control is essential in the process of parts manufacturing and assembling, where eddy current displacement sensors (ECDSs) are widely used owing to the advantages of non-contact sensing, compact volume, and resistance to harsh conditions. To solve the nonlinear characteristics of the sensors, a high-accuracy calibration method based on linearity adjustment is proposed for ECDSs in this paper, which markedly improves the calibration accuracy and then the measurement accuracy. After matching the displacement value and the output voltage of the sensors, firstly, the sensitivity is adjusted according to the specified output range. Then, the weighted support vector adjustment models with the optimal weight of the zero-scale, mid-scale and full-scale are established respectively to cyclically adjust the linearity of the output characteristic curve. Finally, the final linearity adjustment model is obtained, and both the calibration accuracy and precision are verified by the established calibration system. Experimental results show that the linearity of the output characteristic curve of ECDS adjusted by the calibration method reaches over 99.9%, increasing by 1.9–5.0% more than the one of the original. In addition, the measurement accuracy improves from 11–25 μ m to 1–10 μ m in the range of 6mm, which provides a reliable guarantee for high accuracy displacement measurement.

Download Full-text

A Comparison of the Probes with a Cantilever Beam and a Double-Sided Beam in the Tool Edge Profiler for On-Machine Measurement of a Precision Cutting Tool

Machines ◽

10.3390/machines9110271 ◽

2021 ◽

Vol 9 (11) ◽

pp. 271

Author(s):

Bo Wen ◽

Sho Sekine ◽

Shinichi Osawa ◽

Yuki Shimizu ◽

Hiraku Matsukuma ◽

...

Keyword(s):

Cantilever Beam ◽

Cutting Tool ◽

Displacement Sensor ◽

Laser Displacement Sensor ◽

Tool Edge ◽

Edge Profile ◽

Measurement Principle ◽

Beam Type ◽

Tool Position ◽

Tool Cutting

This paper describes a comparison of the mechanical structures (a double-sided beam and a cantilever beam) of a probe in a tool edge profiler for the measurement of a micro-cutting tool. The tool edge profiler consists of a positioning unit having a pair of one-axis DC servo motor stages and a probe unit having a laser displacement sensor and a probe composed of a stylus and a mechanical beam; on-machine measurement of a tool cutting edge can be conducted with a low contact force through measuring the deformation of the probe by the laser displacement sensor while monitoring the tool position. Meanwhile, the mechanical structure of the probe could affect the performance of measurement of the edge profile of a precision cutting tool. In this paper, the measurement principle of the tool edge profile is firstly introduced; after that, slopes and a top-flat of a cutting tool sample are measured by using a cantilever-type probe and a double-sided beam-type probe, respectively. The measurement performances of the two probes are compared through experiments and theoretical measurement uncertainty analysis.

Download Full-text

Global Calibration of Multi-Cameras Based on Refractive Projection and Ray Tracing

10.20944/preprints201710.0077.v1 ◽

2017 ◽

Author(s):

Mingchi Feng ◽

Xiang Jia ◽

Jingshu Wang ◽

Song Feng ◽

Taixiong Zheng

Keyword(s):

Ray Tracing ◽

Real Data ◽

Calibration Method ◽

Calibration Error ◽

Multiple Cameras ◽

Projection Model ◽

Vision Measurement ◽

3D Computer Vision ◽

Global Calibration ◽

Calibration Methods

Multi-cameras system is widely applied in 3D computer vision especially when multiple cameras are distributed on both sides of the measured object. The calibration methods of multi-cameras system are critical to the accuracy of vision measurement and the key is to find an appropriate calibration target. In this paper, a high-precision camera calibration method for multi-cameras system based on transparent glass checkerboard and ray tracing is described, which is used to calibrate multiple cameras distributed on both sides of the glass checkerboard. Firstly, the intrinsic parameters of each camera is obtained by Zhang’s calibration method. Then, multiple cameras capture several images from the front and back of the glass checkerboard with different orientations, and all images contain distinct grid corners. As the cameras on one side are not affected by the refraction of glass checkerboard, extrinsic parameters can be directly calculated. However, the cameras on another side are influenced by the refraction of glass checkerboard, and the direct use of projection model will produce calibration error. A multi-cameras calibration method using refractive projection model and ray tracing is developed to eliminate this error. Furthermore, both synthetic and real data are employed to validate the proposed approach. The experimental results of refractive calibration show that the error of the 3D reconstruction is smaller than 0.2 mm, the relative errors of both rotation and translation are less than 0.014%, and the mean and standard deviation of reprojection error of 4-cameras system are 0.00007 and 0.4543 pixel. The proposed method is flexible, high accurate, and simple to carry out.

Download Full-text