| The line scale is a kind of standard or etalon,which is mainly used for length measurement and length value transferring.Steel tape,as one kind of line scale,plays a very important application role in daily life and industrial production.The accuracy of the nominal value has a directly effect on the machining accuracy and the quality of the products.As a result,periodic verification of the steel tape is imperative.Because of the low degree of automation,poor accuracy and stability of the traditional verification way,it is urgent to develop an automatic high-precision verification instrument.With the development of automatic control technology,visual detection technology are applied more and more widely in non-contact geometric measurements.Based on the original steel tape verification platform,we propose that measure deviations by vision detection technology,with automatic control systems and electromechanical actuators.In order to achieve the automation of steel tape verification process,the main work of this paper is as follows:1.To promote the range of applications,on the basis of the verification platform with wider circulation,we build an automatically walking tour trolley,a camera loading on it.Design a control circuit board based on Freescale MC9S08JM60.PC interacts with the microcontroller through serial communication by HC-05 bluetooth module and control the trolley’s movement.The trolley is driven by a stepping motor.We target measuring points by metal slide,set on one side of the verification platform,triggering proximity switches,set on the trolley.At the same time,camera takes images and then PC processes them.The motion way is verified and evaluated through experiments.2.Due to the flatness error of the verification platform and machine manufacturing error,a new calibration method is proposed in this paper which is defined as the float equivalent method,which can decrease the error cause by object distance changing at different measuring points.This method is a development of the standard component calibration method in a 2D image measuring system.Considering that the standard component and measured piece are present in the field simultaneously,calibration is conducted everytime before measuring.This method has the advantage of reducing the influence of conditions changing on the accuracy and improving the precision of retention.3.To promote and strength the function of trolley and realize wireless,apply to the verification of the hand-held laser range finder,image processing system based on DM6437 is attempted and researched.We introduce the structure of system,transmission and processing of image data.Design and analyze the image processing algorithm,which is used to the verification of black tape and standard tape.Currently,the automatic steel tape verification system has been developed successfully and running trouble-free for over three months. |
