Wind Speed Measurement System Of Mine Pipeline Based On Particle Image Analysis

The wind speed monitoring for pipeline in mine ventilation systems is an indispensable and fundamental part of the entire coal mine safety production.The pipeline typically contains a complex mixture of gases and dust particles,and the commonly used velocimetry instruments have deficiencies such as needing to be adjusted regularly,the sensitive components easily damaged or blocked by dust,and the problem of decreasing measurement accuracy and precision at low wind speeds.In view of the characteristics of ventilation pipelines distributing a considerable amount of dust particles,a method for measuring the wind speed of mine pipeline by particle motion blur image analysis is proposed in this thesis.Based on the particle size,wind speed range to be measured and other conditions,an optical system based on a CCD industrial camera and telecentric lens was designed in the thesis,which can resolve particles down to 10?m.The camera exposure time is adjustable between 1?s-1s,with the light source that can control light intensity,the blur length of the particles in images can be automatically adjusted,so that the appropriate particle motion blur image in different speed ranges can be acquired.In accordance with the characteristics of particle blur image,the image processing algorithm and flow velocity measurement method were designed.After image pre-processing,motion particle identification and segmentation steps,the clear particle image is obtained.Then suitable target particles are screened with statistical histogram or Kmeans clustering based methods,the sub-pixel motion scale corresponding to each target particle is also extracted,and finaly the average speed of the wind is calculated in combination with the exposure time used.For real-time image processing calculation and control requirements of the measurement system,a highperformance embedded development board with RK3399 processor as the core was selected to be the system control and calculation center,and the velocimetry application software using Qt platform is designed,combined with the Open Cv open source image processing library,the control of the speed measurement process,airflow velocity calculation,results display and other functions were realized in the software.Two experimental platforms were designed and constructed in the thesis,and the measurement system calibration experiment as well as the wind speed measurement of mine pipeline simulation experiment were completed.Through these experiments,the validity of the proposed method in terms of principle and theory were verified,and the functions of the measurement system were refined.Theoretically,the wind speed in the range of 0-30m/s can be measured by the system.The experimental results show that the system accuracy reaches 0.1m/s in a certain speed range and 0.05m/s at lower speed.