Research On Phase Technology In Structured Light Vision Measurement

The structured light vision measurement is a technique that obtains the surface depth information of the measured object by projecting a grating stripe on the surface of the measured object and then acquiring the phase information highly modulated by the surface of the measured object.Its related technologies are widely used in many fields,such as reverse engineering,industrial production,and medicine.The phase processing technology is one of the key technologies of structured light vision measurement,which determines the measurement accuracy.Focusing on the related processing technology of phase,the author had done amounts of researches on structural light vision measurement,analyzing the corresponding technical methods.The following are the main researching content in this paper.(1)The system model of structural light vision measurement has been studied.According to the system mathematical model of structural light vision measurement,the relationship between image pixel coordinates,phase and camera coordinates is analyzed.Hardware system is designed,while CCD camera and digital projector is selected.(2)For non-sinusoidal errors in system of structured light measurement,phase correction technique is studied.The theoretical analysis of the non-sinusoidal errors of the grating stripe acquired by the camera indicates the causes of the phase error.Based on analysis of Gamma nonlinear effect model and lens defocusing effect,the method of structural light phase correction based on the relationship of phase mapping has been researched.The correctness of the theoretical analysis has been verified by the experiment,while the correction experiment for non-sinusoidal grating stripe has been done.The experiment results show that this method can significantly reduce the phase error.(3)The technology of phase unwrapping is studied.According to the process of phase unwrapping,the method of acquiring unwrapped phase is analyzed,focusing on the phase shift method for unwrapping phase.The method using multi-frequency heterodyne principle and radial basis function is analyzed.For the shortcomings,different widths of radial basis function are selected for different image complexity regions,and the phase unwrapping method using radial basis function is improved.The phase unwrapping experiment was performed using the simulated unwrapped phase.The experiment results show that the improved method has better phase unwrapping effect and is more robust tonoise.(4)The system of structured light vision measurement is implemented.According to the system mathematical model of structural light vision measurement,the construction of measurement platform and the design of software were completed,and then the projector and camera were calibrated.Combined with the research methods in this paper and calibration parameters,plane and ladder-like workpieces are measured.The experiment results show that this method is feasible and the measurement results are within the expected range.