Study On The Automatic Aiming System Of Wide Line Measures

Wide line measures are important tools for quantity transmission of length.Every year there are large quantities of wide line measurs require calibration of error of indication in our country.Traditional calibration method for wide line measures rely mainly on the human eyes to achieve,not only a heavy workload,staff needs to be calibrated with the completion,and there is the influence of subjective factors calibration results.To achieve automatic calibration based on machine vision is the main direction of the development of wide line measures calibration techniques,in which wide line measurs automatic aiming is the core of the technology.Accordance with the existing problems of large quantities for the wide line measures automatic aiming,the main research work is as follows:Firstly,the wide line measures characteristics and calibration requirements are studied.Research on the key technology and requirements of wide line measures automatic calibration.In addition,detailed digital image processing technology is researched and analyzes its impact.Secondly,based on the 80 m large standard device,used in the image wireless transmission mode,develope a wide line measures image acquisition system,and develop the software operating system with C#,the trackless,power supply integrated wide line measures automatic calibration is developed.Furthermore,the image noise and wide line measures edge features is studied.differential neighborhood extreme centerline extraction algorithm,extraction algorithm based on the intersection of the center line of least-squares fitting and centerline extraction based on sobel operator neighborhood extreme algorithm are applied,which are fit for different kind of wide line measures automatic calibration.The relationship between pixel calibration coefficient and travel is analyzed,in the same field of view,the farther tavel is,the better reliability of pixel calibration coefficient is.The automatic calibration experiments on third-class standard metal line scale,standard steel tape measure,bar code rod etc.are made,which show that the developed system meet wide line measures automatic calibration.Finally,the standard uncertainty of the system was evaluated.Third-class standard metal line scale’s standard uncertainty is u_c =0.86μm+1.5×10^-6L,and the expanded uncertainty is U=1.72μm+3.0×10^-6L.Standard steel tape measure standard uncertainty is u_c =1.32μm+1.2×10^-6L,and expanded uncertainty is U=2.64μm+2.3×10^-6L.