Research On RTK And UWB Fusion Positioning System For Trains In Depot

When the train runs on the main line,the automatic train protection system ensures the operation safety.However,in the depot,due to the increasing number of tracks and trains,the spacing between trains becomes shorter,which makes the operation environment more complex.As a result,the automatic train protection system can’t play a good role in the depot.Therefore,a set of vehicle dispatching system suitable for the special environment of the depot is needed.The system can realize high-precision train positioning in the depot,and then make overall arrangement for the train.To meet this demand,the thesis proposes a real-time kinematic(RTK)differential and ultra wide band(UWB)fusion positioning system for trains in depot.Since there are indoor and outdoor positioning scenes in the depot,the system realizes high-precision train positioning by integrating the positioning information of RTK and UWB.Firstly,after comparing the four positioning methods of UWB,the thesis selects the positioning method of signal arrival time difference to realize the indoor positioning of the train,and expounds the Chan algorithm,Taylor algorithm and Chan-Taylor algorithm for estimating the position of this method.Their position estimation accuracy under different noise variance and the number of base stations is compared through simulation.Secondly,it expounds the advantages of train outdoor positioning through RTK,and analyzes the satellite signal observation model and differential positioning model of RTK.And the whole cycle ambiguity is fixed by LAMBDA algorithm.Then the fusion location model of RTK and UWB is described,and a method to judge the effectiveness of fusion is proposed.In view of the shortcomings of Kalman filter in multi-information fusion,the thesis proposes to realize the fusion of train positioning information through extended Kalman filter,and expounds the flow of generalized extension filter algorithm in processing positioning data.Finally,the prototype of RTK and UWB fusion positioning system for the train in the depot is completed,and the hardware circuit of the system and the design flow of fusion positioning program are introduced.Through the field test in the depot,the results show that the extended Kalman filter algorithm is used to fuse the positioning results of UWB and RTK,and then the generalized extension filter algorithm is used to process the fusion positioning results,which makes the system fusion positioning stable and accurate.