Relative Magnetic Position and Rotation Sensor Assisted Dual Foot Pedestrian Dead Reckoning

Abstract

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 and attitude 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 work 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, the ranging sensor is replaced with two small magnetic sensors that provide a 6 degree-of-freedom relative pose estimate between the sensors. In addition to a ranging measurement, this paper will introduce the use of a relative rotation measurement update to assist with drift reduction.