Stereo Measurement Of Three-Dimensional Workpiece

With the continuous development of worldwide industries,the pursuit of efficiency and precision makes a series of changes in the industry.The sizes of a workpiece is strictly requested in industrial building and machining processes,so the measurement of the size parameters of three-dimensional workpiece is particularly of significance.Although there are many measurement methods for three-dimensional workpiece at home and abroad,and various methods have their own advantages,the efficiency of measurement,precision of measurement,costs of measurement and other aspects should be considered.All these methods have their own limitations and deficiency.How to find a method with higher precision,higher efficiency and lower costs to stereo measurement of a three-dimensional workpiece is a hot area of research in the modern industrial circle.Encoded structured light technology is usually applied to the reconstruction of the objects surface profile.Such as face modeling,criminal investigation and the medical.The main purpose is to restore the objects surface feature profile.there is no specific requirements for precision.The article has applied the encoded structured light technology to three-dimensional workpiece measurement.Firstly,after studying the mathematics modeling and calibration technology of the used optical devices,and considering the factors such as the efficiency and the environment requirement,a more suitable calibration method is selected for the calibration of the projector.Then,the article took deeply investigation on the methods of generating the encoded image,the coding and decoding technology of encoded structured light,and the image preprocessing method of decoded image.The key technologies involved are as follows: Firstly,the article used the double-arm spin filter algorithm on the sine phase shifting image filtering,not only filtering out the high frequency noise effectively,but also protected the details of pattern.Secondly.The article ameliorated the traditional binarization method and achieved excellent results via using new threshold selection rules on the binarization for gray code image.Thirdly,for phase unwrapping having large error in the sine phase shifting method,combine the gray code strategy with the sine phase shifting method,and the period dislocation is corrected.the bumps of the absolute phase diagram are eliminated.Finally,many common three dimensional industrial workpieces by utilizing the calibration results are three-dimentionally measured.The data acquisition of three-dimensional front view has finished in a short period of time.The values calculated of the workpieces have been acquired and compared with the real values.Then the error sources in the experiment can be analyzed.The experimental results show that three-dimensional measurement system have recovered the profile of three-dimensional workpiece.And the accuracy of measurement can reach mm level.Compared with the measurement method commonly used in the industry,the efficiency of the measurement work has been improved.