Research On Three-dimensional Indoor Localization Algorithm Based On PDR And WIFI

Indoor positioning has become a hot topic in the field of positioning in recent years,but most of the proposed location methods are used in two-dimensional indoor area.With the rapid development of the economy,the rate of urbanization has increased,and many high buildings have been built,thus the two-dimensional area indoor positioning can't meet the needs of daily life.At the same time,a highly precise,low-cost and real-time positioning method is also a problem to be solved in the field of indoor positioning.In this paper,smart phone is used as the research platform.Specifically,this paper uses WIFI module and various sensors integrated in smart phone to collect data,focusing on the method of relative barometer altitude measurement,three-dimensional pedestrian dead reckoning localization algorithm and the method of using Unscented Kalman filter algorithm to fuse WIFI location algorithm and improved three-dimensional PDR location algorithm.The main research contents of this paper are as follows.The principle of barometric altimetry is analyzed,and a floor judgment algorithm based on relative barometer altitude measurement is discussed.The atmospheric pressure in the building is relatively stable within a certain period of time,this method uses relative pressure to measure height and judges which floor is the pedestrian in according to building's height information.This method allows a certain amount of error,its absolute value must be less than half of the height of the floor.An improved three-dimensional PDR localization algorithm is proposed.On one hand,when the pedestrian is detected walking horizontally,we use the floor judgment algorithm based on relative barometer altitude measurement to get the height of the pedestrian according to the building's height information.We use traditional three-dimensional PDR localization algorithm to calculate the height of the pedestrian for other motion posture.On the other hand,after using traditional three-dimensional PDR localization algorithm to calculate the data of pedestrian's X axes and Y axes when the pedestrian is detected walking at the narrow corridor area,this improved algorithm sets the longitudinal coordinate values of corridor for the medium value of the corridor.After that,the next step is calculated for the pedestrian.The improved three-dimensional PDR localization algorithm reduces the degree of error accumulation and the location error under certain conditions.This paper discusses the advantages and disadvantages when we use the traditional three-dimensional PDR location algorithm and the indoor fingerprint location algorithm based on WIFI alone.We set the starting value of the Unscented Kalman filter algorithm and the improved three-dimensional PDR localization algorithm with the first result of WIFI signal fingerprint positioning.We use Unscented Kalman filter algorithm to fuse the WIFI fingerprinting positioning algorithm and the improved three-dimensional PDR localization algorithm.The results of the experiments show that the fusion algorithm improves the accuracy and stability of the positioning algorithm.