Abstract
In this paper, a scheme is presented for fusing a foot-mounted Inertial Measurement Unit (IMU) and a floor map to provide ubiquitous positioning in a number of settings, such as in a supermarket as a shopping guide, in a fire emergency service for navigation, or with a hospital patient to be tracked. First, several Zero-Velocity Detection (ZDET) algorithms are compared and discussed when used in the static detection of a pedestrian. By introducing information on the Zero Velocity of the pedestrian, fused with a magnetometer measurement, an improved Pedestrian Dead Reckoning (PDR) model is developed to constrain the accumulating errors associated with the PDR positioning. Second, a Correlation Matching Algorithm based on map projection (CMAP) is presented, and a zone division of a floor map is demonstrated for fusion of the PDR algorithm. Finally, in order to use the dynamic characteristics of a pedestrian’s trajectory, the Adaptive Unscented Kalman Filter (A-UKF) is applied to tightly integrate the IMU, magnetometers and floor map for ubiquitous positioning. The results of a field experiment performed on the fourth floor of the School of Environmental Science and Spatial Informatics (SESSI) building on the China University of Mining and Technology (CUMT) campus confirm that the proposed scheme can reliably achieve meter-level positioning.
Highlights
Pedestrian Dead Reckoning (PDR) [1,2] is a priority technique for the first responder ubiquitous positioning system
Where m and n denote the magnetometer and the gyroscope, respectively, and α, β and γ are the weights of the current measurements from the gyroscope and the magnetometer. θm,k and θg,k denote the measurements acquired by the gyroscope and the magnetometer, respectively, for the k th step. θm is the standard deviation of the magnetometer, and θc is the correlation between the magnetometer and the gyroscope readings. θ∆,c is the difference between θm,k and θg,k . θ∆,m is the difference in the magnetometer readings between two consecutive steps k and k − 1
The results reveal that the pseudo-heading measurements recorded by the magnetometer before and after the turn are considerably smoothed by the proposed algorithm, reducing fluctuation to a certain extent [12]
Summary
Pedestrian Dead Reckoning (PDR) [1,2] is a priority technique for the first responder ubiquitous positioning system. Considering the different walking patterns of different users, the Zero-velocity information, which can improve the position result, can be used to detect the step and calculate the step length. To overcome the constraints we elaborated on before, a floor map can be used to further calibrate the bias and correct for unreasonable positioning results, keeping the walking trace under control. It works by rectifying the weight of the position information or correcting the heading angle, among others. Zero-velocity is detected and used to develop an improved PDR model, and thereafter, it is used to fuse floor map topology to provide a more accurate position without any other hardware preparation.
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