Research On Indoor Positioning Algorithm Based On Dead Reckoning And Wi-Fi

Following the advanced development of internet and mobile communicationtechnology, Location-based Services (LBS) have been widely applied in the healthcare,logistics, entertainment industries etc and have become the hot research area in the field ofinformation technology. How to obtain the location information in an efficient andcost-effective way is the key problem of the LBS to be solved urgently. The globalpositioning system (GPS) can provides the accurate position for tracking users in outdoorenvironments. However, the GPS-based scheme cannot be applied to indoor environments.At present numerous existing approaches to indoor location have various limitations. Aswell, numerous previous approaches have used dedicated sensors that are strapped to thebody. This limits the practicability of the system and increases the burden on the user.Therefore, in order to provide diverse LBS in indoor environments and reduce the variouslimitations of previous existing methods, based on the analysis of the existing approachesto indoor tracking, in accordance with the idea of combining the smart phone with indoorpedestrian tracking, the paper proposes an indoor pedestrian tracking method whichcomprises a pedestrian dead reckoning sub-system and a ranging sub-system with Wi-Fiwireless signals auxiliary. And focused on the following aspects:Firstly, put forward a pedestrian step detection algorithm. According to the analysisof the physiological characteristics of a pedestrian walking behavior, a pedestrian stepdetection algorithm is realized using accelerometer’s signals. Based on the analysis andfeature extraction for the raw data that are received by the accelerometer in threeorthogonal directions, establish a step mode. And a local variance of acceleration methodis proposed to step identification.Secondly, a pedestrian dead reckoning method based on the low cost inertial sensorsembedded in the smart phone is presented. Taking into account that the performance ofinertial sensors embedded in the smart phone can’t meet the accuracy requirement oftraditional inertial navigation mechanism, if we still compute the displacement by directlydouble integrating the acceleration measurements, the error of dead reckoning can accumulate over time, the dissertation realize a pedestrian dead reckoning method usingaccelerometer’s signals to detect step, choosing a constant step length estimation modeland using digital compass to observe the heading orientation. And focused on the threecore problem: steps detection, step length calculation and heading orientation estimation.Thirdly, based on the sparse Wi-Fi infrastructure, a location correction scheme is putforward to bound the accumulated tracking error. Taking into account that dead reckoningapproach relies on sensors and suffers from error accumulation, some correction schemeneed to be put forward to adjust the location. In this paper, taking into account that theWi-Fi-based absolute positioning method need to deploy a large number of Wi-Fiinfrastructure, the paper put forward a probabilistic fusion sparse scheme to adjust thelocation and points out the value of sparse. In addition, the paper analyzes the relationshipbetween the received signal strength and the distance and gives the parameter values ofloss model which are fit to the experimental environment.Finally, experimental results show that the proposed method is feasible and effective,and the analysis of experimental results are made.