Return to Session B4b

Session B4b: Sensor Fusion

Relative Magnetic Position Sensor Assisted Dual Foot IMU Pedestrian Dead Reckoning
Jenario Y. Johnson and Clark N. Taylor, Air Force Institute of Technology, Wright-Patterson AFB, USA
Location: Beacon B

The use of wearable foot-based inertial measurement units (IMUs) incorporated in a navigation system can address the problem of single-person location tracking in situations and environments where GPS signals may be unavailable or inconsistent; e.g., in buildings. This Pedestrian Dead Reckoning (PDR) approach, which enables standalone personal tracking, is an idea that has been attempted many times with varying degrees of success. There are two main approaches to solve this difficult problem: the first is to use inertial measurement units (IMUs) in a filter to apply stride-length, heading correction, and zero-velocity updates to a Kalman filter to get a position solution, while the other is to use Machine Learning techniques to better identify and classify a person’s movement to achieve an accurate position. This paper continues on the path of the former method by investigating the feasibility of PDR using a pair of low cost IMUs along with a pair of relative position magnetic sensors connected to an individual’s feet.
Laverne, et al., [1] have shown that incorporating a ranging measurement between two IMU-based foot sensors significantly increases the accuracy of the pedestrian dead reckoning (PDR) solution. This prior work, however, utilized IMUs that were larger and heavier than desired for a PDR application. We will be utilizing a solution more desirable for wearable PDR applications by incorporating smaller, low cost, commercial grade IMUs. To compensate for this degradation in quality, we replace the ranging sensor with two small magnetic sensors that provide a 6 degree-of-freedom relative pose estimate between the sensors. This magnetic relative positioning assisted PDR algorithm utilizes a single estimator with position, velocity, and attitude being estimated for each foot and then applying the relative measurements between these two state estimates.
This paper will present the accuracy results of the estimated position from our relative magnetic PDR system. These results will be compared to the PDR system without the ranging measurement and “truth” as generated by a GNSS/IMU fused solution. The data will be collected from walking a common track and the same ZUPT step detection algorithm will be used for each configuration.
[1] Laverne, M., George, M., Lord, D., Kelly, A., & Mukherjee, T. (2011). Experimental Validation of Foot to Foot Range Measurements in Pedestrian Tracking.



Return to Session B4b