The Implement Of Anchor-Free Localization Based On Distance Information

Positioning services have played an indispensable role in the development of society’s informatization.GPS can provide accurate positioning in outdoor environment.But in indoor environment,due to the GPS signals are blocked by buildings,the accuracy of GPS is too low to provide positionging services.Accurate indoor positioning technology can bring convenient indoor services to people,so it is urgent to develop an easy to implement,lowcost,high-precision indoor positioning method to meet people’s needs for indoor location services.At present,most of the commonly used positioning technologies require positioning anchor points or collecting fingerprint map data in advance,which leads to high cost and great restrictions on the use environment.In addition,the existing positioning technologies mostly determine the absolute position of a single positioning target,and the positioning technologies for determining the relative positions of multiple positioning targets are still less studied.In order to solve the above problems,this paper combines the distance information of UWB(Ultra-Wide-Band)ranging with PDR(Pedestrian Dead Reckoning)method,put forward an anchor-free positioning method based on distance information,which can achieve multi-target positioning without anchor points,and builds anchor-free positioning system to implements it.The main work includes the following aspects:1.Investigate the implementation principle of traditional pedestrian dead reckoning method,and implement it from three aspects: step frequency detection,step length estimation and direction estimation.The dynamic threshold is used to improve the step frequency detection,and by fusing the data of multi-sensor,the accuracy of direction estimation is improved;2.The UWB signal and its ranging principle are introduced in detail,several sets of ranging experiments are performed using the UWB ranging module based on DWM1000,which proves that its ranging performance can reach centimeter level.The commonly used location information based positioning algorithm is introduced.According to the characteristics of the anchor-free positioning system in this paper,the TOA positioning algorithm is selected for improvement.The distance information is used to improve the weight of the position estimation in the TOA positioning algorithm,so an improved weighting TOA positioning algorithm is proposed.3.By fusing UWB ranging information and improved pedestrian dead reckoning method,an anchor-free positioning algorithm based on distance information is proposed.The algorithm is implemented from three steps: fuzzy position determination,dual target positioning,and multi-target positioning.The positioning algorithm can determine the relative positions of multiple positioning targets without anchors4.Anchor-free positioning system was designed and implemented.The data collection completed the collection of sensor data on the mobile phone side,the collection of mobile phone data on the server side and the UWB data collection on the server side.Finally,the collected data is integrated to achieve the multi-target positioning without anchor points.The positioning interface of the anchor-free positioning system can display the relative position of each positioning target.