Research On Power Line Distance Measuring Method Based On UAV Image Sequence

With the rapid development of national grid industry,electric power security has become a more and more important issue.In order to grasp operation condition of the electrical lines and eliminate potential hidden dangers,vast manpower and resource is spent to conduct power inspection every year.However,traditional manual inspection is quite expensive and usually accompanied with a high false detection rate,many intelligent and efficient inspection methods have been put forward.UAV(unmanned aerial vehicle)based inspection methods are widely utilized in applications as a result of its advantages of security,speed and multi-view detection.Power Line distance measuring is an important part of UAV power inspection,which mainly includes measuring the distance between the power line and the ground features below the line,and detecting the potential danger.The existing power line ranging methods are mainly divided into two categories: power line ranging method based on visual measurement technology and method based on laser measurement technology.Due to its small size,light weight and low cost,the power line ranging method based on visual measurement technology has been widely used.Based on analyzing and summarizing the characteristics of existing power line ranging method based on visual photogrammetry,a power line ranging method based on tower information is presented in the paper to overcome the problem faced by UAV equipped with high accuracy POS system,which puts a requirement on the UAV load and increases the cost at the same time.The main work is as follows:A positioning and posing method based on the outer contour is proposed.By comparing the contour of the tower model obtained by simulation under known position and posture and the contour of the tower extracted from a UAV sequence image,we can calculate the similarity under some criterion.When the similarity is bigger than a certain threshold,the simulated image is considered to be the same image as the real image.The position and orientation parameters of the simulated image are considered the position and orientation parameters of the real sequence image,so as to solve the positioning and posing parameters of the camera.A power line suspension equation estimation method based on curve edge matching is proposed.According to the distance map of the actual image taken by UAV and the edge of the simulated image,we could compare the curvature of curves in the actual image and the simulated image and calculate its similarity measure.Using the mapping relations between parabolic equation parameters and similarity measures to constantly optimized the parameters.When the similarity measure converges to a certain threshold,the curve on the two images is regarded as the same curve,then the parameters of the power line equation are determined,and the three-dimensional equation of the power line is obtained.The validity of the proposed scheme and method is verified by simulation data.