Research On 3D High Precision Indoor Positioning Method

With the maturity of 5G technology and the arrival of the Internet of Things era,location-based services have gradually penetrated into every comer of life.Traditional outdoor positioning technology performs poorly in indoor environment.Bluetooth,infrared,inertial navigation,geomagnetism and other technologies have been deeply studied and applied in the field of indoor positioning,but the positioning accuracy is not very high.The ultra-wideband system based on time difference can achieve centimeter-level positioning.At the same time,the positioning system based on time difference needs accurate clock synchronization,while the existing clock synchronization method for shopping malls,airports,stations and other large spaces is to divide the large space into multiple small spaces,and then realize single-stage clock synchronization in small spaces.There are some problems in this method,such as the delay of small space crossing judgment and the error of small space boundary positioning.Therefore,we propose an ultra-wideband three-dimensional positioning method assisted by air pressure sensor.Ultra-wideband technology has the unique advantages of strong penetration,low power consumption and high multipath resolution.However,in the three-dimensional positioning of large space,ultra-wideband technology needs to solve two problems:(1)optimization of base station clock synchronization error;The layout planning of base stations is complex.For the problem of base station clock synchronization error,this thesis first realizes the whole network clock synchronization based on the same reference clock in a large space;Then,the error of the whole network clock synchronization is optimized by using the differential correction method to improve the positioning accuracy.To solve the problem of complex layout planning of base stations,this thesis introduces an air pressure sensor to measure the change of height,which reduces the layout number and planning complexity of base stations.In this thesis,firstly,the clock synchronization model is established,and the realization of clock synchronization is explained in detail.On this basis,the errors in the clock synchronization process are analyzed,the main error items causing positioning errors in clock synchronization are found out,and the errors in clock synchronization process are optimized by using differential correction method.Simulation verifies the optimization effect of differential correction method on clock synchronization error.Finally,the experiment proves that the differential correction method can effectively reduce the clock error and improve the positioning accuracy.In this thesis,firstly,the characteristics of the data collected by the air pressure sensor are analyzed;secondly,the acceleration sensor is used to assist the air pressure sensor to judge the motion posture;and then,the differential air pressure altimetry method is used to achieve high-precision elevation measurement.Secondly,this elevation measurement is introduced into UWB indoor positioning to achieve high-precision 3D positioning.Finally,the ultra-wideband 3D positioning method assisted by air pressure sensor is simulated.It solves the problem that the ultra-wideband 3D indoor positioning system needs the base stations to be arranged in different horizontal planes,and reduces the difficulty of base station layout planning.