WiFi辅助的行人航位推算算法

PDR algorithm with WiFi-aided

行人航位推算(PDR)中,惯性传感器误差不断积累,提出一种基于Wi Fi辅助的位置矫正方法。当行人行至信号强度大于一定阈值的无线接入点(AP)时,将当前位置重置为此AP的位置坐标。针对当前PDR算法中步长估算精度低及普适性差等问题,提出了一种Wi Fi辅助的频率—步长模型动态调整方法。当Wi Fi信号强度低于设定阈值时,对合加速度进行快速傅立叶变换(FFT)变换得出实时频率,采用频率—步长模型估计步长;当Wi Fi信号强度连续两次达到设定阈值时,将频率估计步长和Wi Fi估计步长根据接收信号强度指示(RSSI)大小进行加权得出融合步长,以此为基准对频率—步长模型参数进行反馈调整,调整后的模型用于下一阶段的PDR。为验证所提方法,在电气楼设计相关实验,结果表明,位置矫正有效消除了惯性传感器的累积误差,模型参数调整后PDR误差降低20%以上。

In pedestrian dead reckoning(PDR),a position correction method based on Wi Fi-aided is proposed to eliminate inertial accumulation error.When the pedestrian reaches the access point(AP)where the signal strength is greater than a certain threshold,the positioning coordinate is reset to the coordinate of the AP.In addition,In the current PDR algorithm,the precision of step size estimation is low and the universality is poor,a Wi Fi-aided dynamic adjustment method of frequency-step model is proposed.When the RSSI of Wi Fi is lower than the set threshold,the real-time frequency was calculated by fast Fourier transform(FFT)on the sum acceleration,and to estimate step size through the frequency-step model;when the received signal strength indication(RSSI)of Wi Fi reaches a set threshold two times successive,the frequency estimation step and Wi Fi estimation step are weighted according to the RSSI to obtain the fusion step size,the parameters of the frequency-step model are feedback adjustment on the base of fusion step size,the adjusted model for the next phase of PDR.In order to verify the above methods,the experiment is designed in electrical building,the result shows that the position correction effectively eliminates the accumulated error of inertial sensors,and the PDR error is reduced by more than 20%after the adjustment of the model parameters.