| With the continuous improvement of manufacturing technology's requirements for complex surface profile detection technology,the development of a 3D measurement technology with a 360° profile becomes more and more important.However,the existing planar structured light measurement method is difficult to complete the measurement task in a single time because the light is blocked.The measurement method based on the Line structured light can overcome the occlusion problem,but when the center of the light strip is extracted,it is susceptible to noise,and there are problems such as disconnection and distortion.Therefore,based on the in-depth study of the line structured light 3D measurement technology,this thesis develops a phase-based 360° measurement method of the Line structured light complex shape,and establishes several key technologies.The main tasks are as follows:(1)First of all,the principle of structured light measurement is studied,and the deficiencies in the measurement process based on planar structured light are analyzed and demonstrated.A 360° experimental measurement device based on Line structured light is designed and built,and an in-depth study based on hybrid adaptive Line structured light Light knife thinning technology,and carried out 3D measurement experiments,the research found that there are problems such as disconnection and distortion of the Light knife center in the traditional Light strip center extraction process.(2)In response to the above problems,the phase-based Line structured light 360°three-dimensional profile measurement technology research was carried out,and the construction method of the 360° Stripe superimposed fringe pattern was established,and the overlay map measurement was realized by using the Two-dimensional Fourier transform.By changing the noise level,the performance of the phase-unwrapping method based on the transport of intensity equation(TIE)is analyzed,and the discrete cosine transform(DCT)is used to expand the measurement phase.Furthermore,the phase demodulation and unwrapping experiments were performed on the carrier frequency fringe pattern of the Light strips to realize the measurement phase solution,which proved the effectiveness of the developed phase-based Line structured optical demodulation technology.(3)In order to avoid the problems of spectrum aliasing and leakage in the Fourier transform phase demodulation technology,based on the Riesz transform digital phase shift demodulation technology,a single-frame overlapping fringe pattern digital phase shift demodulation method is proposed;Realize the 90°,180°,270° digital phase shift of the light stripe superimposed fringe pattern,and conduct simulation and experimental research and analysis on the sine,phase shift amount error,reconstruction accuracy of the digital phase shift fringe pattern,and prove this The correctness of the method.(4)Considering that the digital phase shift error is large,which affects the further improvement of the phase extraction accuracy,this paper proposes a multi-frame random phase shift fringe pattern phase extraction algorithm,which uses the analytical signal amplitude and offset phase shift to evolve There is the characteristic of the minimum value in the process,and the random phase shift extraction is realized through the one-dimensional search optimization method.Compared with the existing self-calibrated phase extraction method,the proposed method has the characteristics of accuracy,stability and high efficiency.Both optical simulation and experimental data show that the method has higher accuracy and efficiency.The technology developed in this paper provides a way to measure the three-dimensional profile of 360° complex shapes.The proposed demodulation method of light stripe overlay graph based on digital phase shift can avoid the aliasing problem existing in the Fourier transform method,which is useful for the development of new The line structured light three-dimensional profile measurement method has important theoretical and practical value. |
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