| Water meters are the main measuring instruments for residents’ daily water consumption,and the state stipulates that each water meter needs to be compulsorily tested before leaving the factory.At present,the water meter calibration mainly adopts the manual reading method,this method has a low degree of automation,low accuracy,low efficiency,and is susceptible to subjective factors.In view of the long time consuming and heavy testing workload,this thesis proposes to improve the testing efficiency by reducing the water consumption.In order to meet the national calibration standards,this thesis conducts an indepth study on the high-precision calibration of water meters based on machine vision technology to solve the problem of improving the testing accuracy due to the reduction of water consumption.The main research within this thesis is as follows:1.The overall design of the high precision calibration program: This thesis is divided into two parts: hardware and software.The hardware system is mainly used to select industrial cameras,lenses,processors and light sources and to build the experimental platform;The software system mainly implements the design of the high-precision calibration algorithm for water meters.Acquire water meter images through the acquisition equipment,transfer the acquired water meter images to the processor,and output the calibration results by the water meter calibration algorithm processing.2.Research on high precision calibration technology: This thesis implements automatic water meter calibration based on the high-precision measurement of plum pins,and firstly pre-processes the collected images;To precisely locate the position of the plum pins,the first localization of the plum pins is quickly achieved using a shape-based template matching method combined with image pyramidal hierarchical search;Segmentation of plum pins using a threshold-based approach;The selection of the sampling area by using a combination of geometric transformation and logical operation,and the detection of the rotation angle of the plummer tooth by tracking the plummer tooth center of mass in the sampling area;To prevent air bubbles generated during the rotation of the water meter from affecting the statistics of the plummer teeth,the air bubbles were removed using morphological methods.3.ARM-based system construction: This thesis completes the construction of the software system in the development board(target machine)with the help of a PC(host machine)and implements the automatic calibration of the water meter on the ARM development board.Develop and debug the verification algorithm on the host computer,build a crosscompilation environment and cross-compile the Opencv and QT libraries,and port the verification algorithm to the ARM development board with the libraries needed to run on the target machine.4.Experimental tests: In this thesis,the calibration algorithm is tested at three flow rates and compared with the test results of a factory.The experimental results show that the calibration system designed in this thesis has a high calibration accuracy and can realize the improvement of testing efficiency by reducing the water consumption. |
