A new autonomous positioning method of Baseline-RFMDR and Kalman filter solution

Abstract

The development of intelligent positioning requires a new method of low-cost to meet the needs of autonomous positioning or emergency positioning underground. A new method of Baseline Radio Frequency Magnetic Dead Reckoning (Baseline-RFMDR) autonomous positioning is constructed in this paper, to solve the problems of low accuracy of geomagnetic matching positioning and large cumulative errors in Pedestrian Dead Reckoning (PDR) positioning, which provides a new approach for high-precision and stable autonomous positioning of underground personnel. This method combines PDR positioning and geomagnetic matching positioning, with the constraint of baseline distance, which is the distance from the Tag Pair to the reader. The Kalman Filter solution equation for this model is constructed, and the recursive equation for the covariance matrix under baseline constraints is derived. An underground positioning test was conducted using the self-developed Baseline RFMDR positioning device, the results showed that the accuracy of this combined positioning method is significantly better than PDR positioning or geomagnetic matching positioning. At normal speed, the MAE and RMSE of Baseline-RFMDR combined positioning can be kept within 0.12 m in the X direction and within 0.2 m in the Y direction. It’s 88% more accurate in the X direction than PDR, 60% more than geomagnetic matching, 70% more in the Y direction than PDR, and 75% more than geomagnetic matching. At fast speed, the MAE and RMSE of Baseline-RFMDR combined positioning can maintain 0.2 m in the X direction and 0.61 m in the Y direction. It’s 79% more accurate in the X direction than PDR, 21% more than geomagnetic matching, 49% more than PDR in the Y direction, and 46% more than geomagnetic matching. At the same time, Baseline-RFMDR positioning has good robustness. When the initial coordinate error or initial covariance error or Baseline-RFMDR partial failure, the MAE and RMSE of Baseline-RFMDR combined positioning can still be maintained within 0.24 m.