Research On Visual Detection Technology Of Space Scale Relation Of Safety Seat Base

With the popularity of family cars,the problem of children’s riding safety has become increasingly prominent.Automobile accessories,baby products and other industries have put forward stricter standards for the quality of safety seats.The safety evaluation criteria for children riding are included in the C-NCAP evaluation system.At present,most safety seats are manually inspected.The space geometry relationship of the seat is tested by trial installation,which is inefficient and time-consuming.Aiming at the measurement requirement of the space scale relationship of the seat,a visual detection system for the space scale relationship of the seat base is designed and built,which realizes the measurement of the space scale relationship between the waist groove and the arc groove of the seat base by image processing technology.Differing from metal parts,the seat base studied in this paper is plastic,there is no accurate positioning datum.After analyzing the structural characteristics of the base parts,the waist groove is determined as the measuring datum,and the interrelated measuring coordinate system is established.The image of waist groove is acquired by monocular camera.The contour of waist groove is extracted by screening the area of contours and filtering the length-width ratio threshold.Then the size of waist groove is analyzed and the information of center,length and width of waist groove is calculated.The arc groove image is acquired by binocular camera.A SURF feature matching strategy with multiple constraints for arc groove image matching is proposed,and then a complete arc groove image is obtained by using the gradual-in-and-gradual-out method.A corner detection method based on curvature scale space is proposed to accurately extract the corners of the arc groove contour.The arc groove are segmented by corners,and the fitting parameters of each arc segment are obtained by least square method.By calibrating the vision measurement system,the contour size parameters and spatial inclination parameters of waist groove and arc groove are calculated,and the three-dimensional coordinates of contour points are calculated by focal plane projection.Three-dimensional point cloud is generated to reconstruct the contours of waist groove and arc groove.The result shows that the relative error of waist groove width measurement is 2.7%,length measurement is 2.1%,arc groove width measurement is 0.7%,and the direction angle error of space position vector is less than 2 degrees.Finally,the accuracy and error of the system are analyzed.The overall measurement error of the system is 0.299 mm,which meets the accuracy requirement of 0.5 mm given by the technical index of the seat.