Research On Automatic Verification Device Of Digimatic Caliper

Digimatic caliper is one of the most commonly used length measuring instruments in industrial field.The wear environment and corrosion will lead to the change of measurement accuracy,so the workload of regular verification is very heavy.However,at present,the metrology institutions are still mainly in the way of manual verification,and there are some problems such as low efficiency,large error of human factors and poor repeatability.The research on automatic digital display caliper verification technology has a wide application prospect.This paper takes the development of digimatic caliper automatic verification device as the target to carry out the research,and the main research contents include:(1)The whole structure of automatic verification device was designed.According to Abbe principle,the installation scheme of calipers was designed to reduce the influence of Abbe error on measurement accuracy;Used grating ruler instead of measuring block as the length standard,it was easy to reproduce the length of any interval;The measurement software based on C# language was developed to realize the automatic control of caliper verification process.(2)Aiming at the problem of image overexposure caused by reflection of caliper display screen,the illumination Angle of light source was optimized,and The high definition image acquisition of caliper value was realized.We collected images of target area to realize localization,denoising,binarization and morphological segmentation,which was carried out on the collected images to highlight useful information and laid a foundation for digital recognition.(3)The traditional threading method had the disadvantage of low digital recognition rate with an inclined Angle to the vertical direction,while the pattern matching method had the disadvantage of long time for digital recognition.An improved line-crossing method was proposed in this paper,through the application of Radon transform,the digital inclination Angle in the image was measured,the regional dividing line of each number was segmented,the intersection information of the Numbers was searched,the digital decoding table was compared and the digital recognition results were obtained.Experimental results showed that digital recognition rate of this method was 98%.(4)The error verification experiment of digimatic caliper was carried out with the established automatic verification device,the measurement process was developed,and the measurement uncertainty of the verification device was analyzed.It was concluded that the extended measurement uncertainty of the measurement result of the device was4.6μm,which met the precision requirement of JJG30-2012 universal caliper verification regulation for digital caliper automatic verification device.The research showed that the research in this paper improved the degree of automation and efficiency of caliper verification,and it also had extensive reference significance for the mass verification of other traditional measuring tools.