Three-dimensional measurement method and system for key morphological feature on aircraft surface, and method for using system

A three-dimensional measurement method for a key morphological feature on an aircraft surface, implemented by a structured-light measurement system comprising a camera, a projector, and a drive component, the method comprising:

• step S1, planning a three-dimensional measurement point according to information of a rivet and a seam in an aircraft digital model, and obtaining information of a two-dimensional image and a three-dimensional point cloud of the aircraft surface, wherein a direction vector of the measurement point forms an angle β with a seam direction;
• and
• step S2, automatically identifying and extracting position information of the rivet and the seam in the two-dimensional image, and obtaining point clouds corresponding to the rivet and the seam according to correspondence between the two-dimensional image and the three-dimensional point cloud to calculate a concave-convex amount on the rivet, and a gap and a flush of the seam, wherein a method for calculating the gap of the seam comprises:
• finding a nearest point in point clouds on both sides of the seam in a direction perpendicular to the seam to obtain the gap of the seam, wherein the step S1 comprises:
• step S11, extracting normal vector information of each nail head in a measurement area, and calculating a normal vector of a measurement point after averaging;
• step S12, extracting position information of each nail head in the measurement area, and offsetting a measurement distance of l0 along an average normal vector direction after averaging to obtain a position of the measurement point;
• step S13, extracting direction information of the seam in the measurement area, so that a direction vector of the measurement point forms an angle β with a seam direction;
• and
• step S14, taking the position and direction vector of the measurement point as a reference to perform measurement and obtaining information of the two-dimensional image and the three-dimensional point cloud of the aircraft surface.