| In the Internet of Things era,accurate location information is the basis of many intelligent services.In order to compensate for the performance defects of traditional navigation and positioning in complex indoor environment,indoor positioning technology emerged as the times require.Among many indoor positioning technologies,UWB-based ranging and positioning technology has become the mainstream of indoor positioning technology because of its high accuracy,low power consumption and strong anti-jamming ability.Therefore,this paper chooses to use UWB technology to achieve ranging and positioning,and develops the corresponding positioning system to adapt to different applications.Specific research contents are as follows:(1)Based on the UWB chip DWM1001,the UWB indoor positioning system is designed and developed.The hardware of the system is composed of ranging module,data interaction interface and high frequency response power supply module.The software of the system includes ranging,positioning and communication functions.After debugging and testing,the positioning system has perfect functions and stable operation.(2)Aiming at the phenomenon that indoor ranging results are prone to large deviations and fluctuations,an incremental Kalman filter algorithm is proposed.The algorithm can filter out the system error,measurement error and NLOS error in the process of ranging,and verify the ranging under indoor LOS and non-LOS conditions.The accuracy reaches the requirement of less than 10 cm.(3)Three different localization algorithms are designed for different localization scenarios,and the corresponding localization strategy is formulated.For the location scenarios of three base stations,TOA localization algorithm is designed,and the intersection points of space spheres are solved by least squares estimation.For the location scenarios of four base stations,TDOA localization algorithm is designed.The spatial location is solved by Chan algorithm after TOA ranging difference.For the location scenarios where base stations are arranged according to special rules,the idea of weighted K-nearest neighbor algorithm is used.Through the known position around the point to be located,the estimation of the position to be located is completed.The localization algorithm adapted to different situations makes the localization system have certain flexibility.In order to make the algorithm run efficiently on the positioning system,the spatial positioning algorithm is simplified.Firstly,the spatial positioning model is projected onto the xoy plane to complete the plane positioning estimation.Then,the z-direction positioning estimation is completed according to the plane positioning estimation value and the geometric relationship.This design reduces the computational complexity of the algorithm and effectively improves the performance of the positioning system.(4)Based on the development of UWB indoor positioning system,a test platform under the conditions of LOS and NLOS is built indoors.The ranging experiments were carried out under the conditions of ranging distance of 1 m and 2 m,and four different relative rotation angles of UWB antenna.After testing,the ranging accuracy reached 65 mm.The location accuracy of five different locations was tested under the indoor LOS condition.The test results show that the location accuracy can reach 81 mm under the LOS condition.Location test under NLOS condition can not fully simulate the complex indoor NLOS environment It is only tested in a specific NLOS environment and at a test point.The positioning accuracy is 56 mm,which has certain reference value.In the process of experiment,all functions run normally and the system runs stably,which proves that the design of hardware system and software system is reasonable.The algorithm effectively solves the problem of inaccurate ranging and positioning accuracy. |
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