Research On The Key Technology Of The Gap And Face Difference Measurement System For Car Body Panels

In automobile production,the measurement of gap and flush for car body cover is an important way to evaluate the matching precision of the car body.It will directly affect the general appearance of the car body,the fluency,wind noise and the closeness,etc.Most of the automobile factories in China are still using contact measurement methods such as measuring ruler,Cubing model or CMM machine.It is because of the gap between the body covers has many kinds,the foreign equipment has high cost and the limitations of the domestic research.The traditional artificial detection method is not only easy to be disturbed by subjective factors,but also is inefficient.In view of the above phenomenon,this paper designs a set of binocular and double line structured light measuring system with low cost,high accuracy and high efficiency.It is divided into three parts:system design,system calibration and evaluation algorithm.The experimental verification has been made.Firstly,according to the overall requirement of the gap and flush measurement,the hardware and software modules were designed.The hardware system includes the structural design,the camera and lens selection,the image acquisition and the electrical system module.Software system includes the measurement plan management,the brightness control,the image acquisition and processing.Secondly,the calibration method of the system from three parts in detail,they are the light plane and the camera internal parameters and external parameters.In the part of camera calibration reference,design a camera automatic calibration of circular target.The least squares circle fitting method based on the normals gray distribution interpolation is proposed for the target.And the center lattice ordering method based on the principal circle constraint.In the binocular calibration section,a calibration ball based system calibration algorithm is proposed,which simplifies the subsequent operation and improves the accuracy of the system calibration.Finally,a mathematical measurement model based on the segmentation of the feature points is proposed.The experimental results show that the binocular structured light system proposed in this paper has a precision of 0.1mm within the range of 45 degrees,and the single time measurement time is about 1 second.