Study On 3D Measurement Based On Stroboscopic Laser Grating Stripes

With the rapid development of technology and information industry,3D measurement technology is more widely used in industrial production.The 3D measurement based on Digital Light Processing(DLP)is an important means to realize 3D inspection of industrial production.Due to the grating resolution projected by the DLP-based three-dimensional measurement system,there are problems such as fringe resolution,sinusoidal distribution characteristics,and refresh rate limited by hardware conditions.In the three-dimensional high-precision measurement and on-line detection of small-sized objects or objects with certain reflective characteristics,there are problems such as unsatisfactory stripe contrast and poor measurement adaptability.Aiming at these problems,this paper proposes a three-dimensional measurement method based on stroboscopic laser grating stripe from the laser grating stripe source.Based on the study of the characteristics of stroboscopic laser source,a three-dimensional measurement system is designed.The main research contents of this paper are as follows:1.A stroboscopic laser grating stripe projection device is designed,which can project high-brightness,high-definition grating stripes.The projection principle of grating stripe is studied,and the design of optical and mechanical structure,hardware circuit and software is completed.2.Based on the projection characteristics of stroboscopic laser source,the phase-height measurement model is used to establish the mapping relationship between the phase of the grating stripe and the height of the object.The phase shift method and the spatial phase unwrapping algorithm are used to realize the three-dimensional measurement of small-sized objects.3.The performance of the stroboscopic laser source is studied.The relationship between the width and density of the grating stripe and the modulation parameters of the light source and the factors affecting the accuracy of the small-dimensional three-dimensional measurement are analyzed theoretically and experimentally.In order to improve the measurement accuracy,the frequency domain filtering method for improving the sinusoid of stripes and the prism rotation speed control algorithm for improving the phase shift accuracy and stability are studied.4.A small-scale three-dimensional measurement experiment system is built and the system was calibrated.Three-dimensional measurement and reconstruction of small-sized machined parts,small-sized cylindrical gypsum sections and small engine blades with reflective metal surfaces were carried out to verify the effectiveness and adaptability of the three-dimensional measurement system.