Research On Indoor Positioning Fusion Method Based On Magnetic Map And IMU

In recent years,due to the development of Internet and Internet of things technology and the concept of interconnection of all things,the demand for location-based services(LBS)has become more and more,which puts forward higher requirements for the accuracy and cost of indoor positioning technology.In this paper,we study the low-cost and high-precision indoor positioning technology based on the integration of Geomagnetism and inertial navigation.The research content of this paper includes the following parts:1.Gait phase detection algorithm.This paper presents a simple and adaptive threshold gait phase detection algorithm.We construct a variable according to the output of accelerometer and gyroscope,and detect the standing phase through the maximum angular velocity in the gait cycle.We can adaptively detect the standing phase state of a variety of motion states(walking,running,turning and going up and down stairs),and the detection accuracy of gait phase can reach more than 95%.2.Heading estimation algorithm.In this paper,a heading estimation algorithm based on statistical idea is proposed.The algorithm combines the characteristics of high short-term accuracy of inertial navigation system and no accumulation of magnetometer error with time,uses the idea of statistics to deduce the absolute heading at the current time according to the absolute heading at multiple times,uses the percentage method to remove the outliers,and then obtains the heading estimation at the current time through weighted average.The heading angle estimation algorithm proposed in this paper improves the accuracy of heading angle estimation in indoor conditions by 67%.3.Magnetic map construction method.In this paper,a trajectory guided two-dimensional magnetic map construction method is proposed.This method maps the data collected by walking according to the specified trajectory in the area to be built to the real trajectory according to the displacement calculated by the inertial navigation system,and then uses the inverse distance weight method to further refine the magnetic map to meet our accuracy requirements for the magnetic map.The mapping accuracy of the trajectory guided magnetic map construction method proposed in this paper can reach 0.1141m,and the mapping efficiency is more than 1800m~2/h.The cost of constructing magnetic map by this method is only 15.4$(98￥).4.Integrated particle filter method.This paper presents an integrated particle filter algorithm.The algorithm uses two assumptions:1)all noises obey Gaussian distribution;2)The initial position and the results after integrated particle filter are credible enough.The integrated particle filter algorithm proposed in this paper simulates the particle distribution in the case of infinite particles,and integrates similar particles.The algorithm breaks through the limitation of particle number in particle filter algorithm and various improved particle filter algorithms,and fundamentally solves the randomness of particle filter related algorithms.After a large number of experimental tests,the geomagnetic and inertial navigation fusion positioning method in this paper has reached the average positioning accuracy of0.32m,and the average positioning error of 0.32m is in the forefront of indoor positioning technology,and our device cost is only 98 yuan,which fully takes into account the requirements of low cost and high accuracy.