Doppler pose estimation using multiple IMES transmitters for indoor localisation

We propose a Doppler pose estimation method for an indoor messaging system (IMES) (‘pose’ refers to both position and orientation). With this method, both the position and orientation of a receiver are estimated simultaneously by using Doppler shifts produced by moving a receiver antenna with two or more IMES transmitters. The proposed method is evaluated through the identical experiments conducted in two different locations. In these experiments, the position and orientation of the receiver is estimated using two transmitters, and the achievable accuracy is evaluated by changing the separation distance between the transmitter antennas. The experimental results demonstrate that a positioning accuracy higher than a few decimetres and orientation estimation accuracy of higher than a few degrees are achievable when the measurement condition is relatively good (i.e. when the proper separation distance is set between two transmitter antennas and cycle slips do not occur). We also conducted an analysis for the convergence of initial values (which are used for the iterative position and orientation calculation in the nonlinear least-squares method). The results show that the initial values basically converge to appropriate position and orientation values as long as an inverse matrix in the position and orientation estimation process can be calculated. Moreover, we analysed the effect of the number of transmitters on position and orientation estimation precision. The results show that, as the number of transmitters increases, the precision of the position and orientation estimation also increases, and the precision is particularly high in the area surrounded by the transmitters.