Abstract
Because of the particularity of urban underground pipe corridor environment, the distribution of wireless access points is sparse. It causes great interference to a single WiFi positioning method or geomagnetic method. In order to meet the positioning needs of daily inspection staff, this paper proposes a WiFi/geomagnetic combined positioning method. In this combination method, firstly, the collected WiFi strength data was filtered by outlier detection method. Then, the filtered data set was used to construct the offline fingerprint database. In the following positioning operation, the classical k -nearest neighbor algorithm was firstly used for preliminary positioning. Then, a standard circle was constructed based on the points obtained by the algorithm and the actual coordinate points. The diameter of the standard circle was the error, and the geomagnetic data were used for more accurate positioning in this circle. The method reduced the WiFi mismatch rate caused by multipath effects and improved positioning accuracy. Finally, a positioning accuracy experiment was performed in a single AP distribution environment that simulates a pipe corridor environment. The results proves that the WiFi/geomagnetic combined positioning method proposed in this paper is superior to the traditional WiFi and geomagnetic positioning methods in terms of positioning accuracy.
Highlights
With the development of the mobile Internet and the innovation of location-based services, the market potential and application prospects of positioning technology are selfevident
Aiming at the sparseness of access point (AP) distribution in urban underground pipe corridors, that is, the indoor positioning of the coverage of a single AP, because the WiFi location fingerprint single positioning technology is affected by factors such as multipath effects, make the received signal strength fingerprint not unique
This paper proposed that a WiFi/geomagnetic combined positioning method used the WiFi signal strength value after outlier detection and screened to constrain the geomagnetic fingerprint for combined positioning improving the positioning accuracy
Summary
With the development of the mobile Internet and the innovation of location-based services, the market potential and application prospects of positioning technology are selfevident. Loci indicates the position coordinates of the selected neighboring reference point; Di ∈ fMIN KðD1, ⋯, DLÞg represents the set of minimum K RSS distances; ð x, yÞ represents positioning coordinates In this article, both WiFi fingerprints and geomagnetic fingerprints are matched according to the K-nearest neighbor method to obtain the final positioning coordinates. The specific steps of the combined indoor positioning method mentioned in this paper were as follows: firstly, WiFi fingerprint information was collected through the self-developed mobile phone application and was stored in the database on the server. At this time, the fingerprint information was filtered by the outlier detection method. After the double positioning operation, the final positioning coordinate was obtained, that was the positioning coordinate obtained by using the combined positioning method
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