Research On The Method Of Solving The Position Of Small Unmanned Aerial Vehicles Based On MEANSHIFT

Unmanned aerial vehicle(UAV)was invented in the 1920s.With the development of high-tech,UAV will have a broader application prospects in the field of military and civilian.Due to the advantages of its small size,good invisibility,light weight,low cost and high performance,the key technologies of UAV's autonomous flight catch lots of attention.The positioning algorithm of UAV is one of the key technologies in UAV autonomous flight.In recent years,many experts at home and abroad make an in-depth study in positioning method of UAV.In this paper,a new approach based on meanshift target tracking algorithm for real-time positioning of hovering UAV is presented.Firstly,the basic knowledge in the positioning field of UAV and camera calibration theory are introduced.Meanshift target tracking algorithm is introduced in detail.Due to the limitation of meanshift tracking algorithm,Kalman filtering technique is specially used.Using the prediction and correction technology,aiming at the condition of fast moving and occlusion of targets,an improved meanshift algorithm combined with Kalman algorithm is proposed.The goal of this algorithm is to obtain accurate tracking trajectory by two ways.One way is that target tracking is carried on by Kalman prediction directly.The other one is that target tracking is conducted by meanshift algorithm fusing with Kalman correction method.Which begs the question,how is the improved algorithm determining the selection of the tracking ways.It is the key point of this algorithm.In this paper,according to the matching degree of color histogram between known target template and candidate target template,the next step of the algorithm,namely,one way to track,is decided.This method proposed in this study has been testified by sets of experiments to have better robustness.It can achieve the desired goal of the experiments.Secondly,a positioning method based on meanshift target tracking algorithm to calculate UAV location is introduced.To illustrate feasibility and practicality of this method,this method is compared with the positioning method based on camera calibration.Using the improved meanshift target tracking algorithm to extract target tracking trajectory,on the basis of theoretical knowledge applying to any two points of airborne camera images about ratio invariance between the distance in world coordinate system and the corresponding distance in image pixel coordinate system,and through space distance formula,the world coordinate of hovering UAV can be calculated.Finally,the positioning experiments are conducted in the laboratory,and quadrocopter is chosen to be a flying vehicle.The experiments verify the feasibility of this method that the world coordinate of UAV can be calculated by the improved meanshift target tracking algorithm.