Research On Three-Dimensional Of Surface Holes In Work-Piece Based On Grating Projection

The grating projection measurement system can reconstruct the three-dimensional size of the work-piece.However,due to the particularity of the hole and the convex defect,the shadow area is easily generated during the process of image acquisition,which affects the data collection and causes the reconstruction accuracy of the surface holes of the work-piece to be lowered.In order to solve this problem,by analyzing the characteristics of the work-piece hole and the principle of grating projection measurement,this paper proposes the three-dimensional measurement method to reconstruct the three-dimensional defects of the hole.This method detects the thickness of the work-piece and the size of the hole on the work-piece with holes on the surface,and lays a foundation for improving the accuracy of hole reconstruction.Due to the influence of the work-piece thickness,shadows are generated at the edge of the hole,which affects the accuracy of the reconstructed work-piece.This paper proposes a grating projection method using double-projection,which determines the shadow area and binarizes it.Based on the data of the 3D reconstruction,the data of the shadow area is filled,merging with the data of the filled shadow area and the non-shadow area data can realize the three-dimensional reconstruction of the hole on the surface of the work-piece.This paper also analyzes the factors affecting the accuracy of the measurement system,and the main influencing factors(the selection of the grating frequency and the projection angle of the projector)are analyzed and discussed,then selecting the appropriate parameter range to improve the measurement accuracy of the system.Through the measurement of different holes,the measurement accuracy of the measurement system proposed in this paper is obtained.The accuracy of the work-piece thickness can reach 0.05 mm,and the measurement accuracy of the hole diameter reaches 0.1mm.