Research On The Measurement Of Contact Wire Wear Based On Dual Linear CCD Cameras

The contact wire is the main channel of electric locomotive power transmission,and it will lead to serious wear when it get the current through the contact with the pantograph for a long time.If we don't replace it timely,the way will not only affect the current quality through the contact and the pantograph,but also related to the power safety of the Electrified locomotive,so the maintenance of the contact wire,especially the detection of contact wire wear,is very important.The traditional manual fixed point contact wire method has many shortcomings,such as heavy workload,low efficiency and inaccurate.And the majority of domestic non-contact detection equipment can detect the contact height and stagger,but there is no wear measurement function because of the measurement accuracy.Therefore,how to detect accurately and quickly is the main goal of the research design.Based on the theory of binocular vision,the paper had studied the relevant specific processes of the system design.According to the machine vision,this paper analyzes and deduces the object and image ration of linear CCD camera based on the transformation relations of various coordinate systems.At last,the coordinate expression of the object point under the world coordinate is established.From the aspect of practice,the formula is deduced when the deflection angle is different,and extended to the calibration formula.The structure and the contact wire wear is studied independently.The principle of the wear detection was discussed according to the characteristics of linear CCD camera,and the calculation method of wear was given at last.From the point of view of algorithm,the noise problem of the received linear array image is analyzed,and the Gaussian noise is the main noise which we need consider.Then the recursive approximation Gaussian filtering method which also named infinite impulse response filter and wavelet transform denoising method are used respectively.The simulation results about the actual collected contact wear show that recursive implementation of Gaussian filter has a faster denoising speed advantage,and the threshold method and modulus maxima wavelet denoising method are compared.In the edge point recognition,the gradient operator maximal method,the Sigmoidal function fitting method and the DoG edge detection method are expounded respectively,and the sub pixel coordinates at the edge are obtained respectively,and the characteristics of each method are shown.,which laid a foundation for further accurate measurement of contact wire width.The wear detection system is designed according to the requirement of the contact wire real-time detection.On the basis of the actual locomotive size and transmission requirements,the linear array camera and other equipment are selected,and the model is built according to the practical application.And the real-time wear detection software is coded to realize the complete design of the whole system.At last,two truncated contact wires under laboratory conditions were tested in real time,the calibration data were determined,and the errors of the contact wire wear data were compared.Finally,the errors of the contact wire which come from the formula parameters were simulated and analyzed,and the influence of vibration for the wear detection was analyzed emphatically.