f2IMU-R: Pedestrian Navigation by Low-cost Foot-Mounted Dual IMUs and Inter-foot Ranging

TL;DR

This paper presents a pedestrian navigation system using low-cost dual IMUs and inter-foot ultrasonic ranging, improving accuracy and robustness in GPS-denied environments through observability analysis and a Kalman filter in the Earth frame.

Contribution

The paper introduces a novel pedestrian navigation approach combining dual foot-mounted IMUs with inter-foot ranging and a Kalman filter in the Earth frame, enhancing accuracy and robustness.

Findings

Achieves positioning accuracy of about 0.1-0.2% of traveled distance.

Demonstrates improved robustness over traditional methods.

Validates effectiveness through simulation and real experiments.

Abstract

Foot-mounted inertial sensors become popular in many indoor or GPS-denied applications, including but not limited to medical monitoring, gait analysis, soldier and first responder positioning. However, the foot-mounted inertial navigation relies largely on the aid of Zero Velocity Update (ZUPT) and has encountered inherent problems such as heading drift. This paper implements a pedestrian navigation system based on dual foot-mounted low-cost inertial measurement units (IMU) and inter-foot ultrasonic ranging. The observability analysis of the system is performed to investigate the roles of the ZUPT measurement and the foot-to-foot ranging measurement in improving the state estimability. A Kalman-based estimation algorithm is mechanized in the Earth frame, rather than in the common local-level frame, which is found to be effective in depressing the linearization error in Kalman filtering. An ellipsoid constraint in the Earth frame is also proposed to further restrict the height drift. Simulation and real field experiments show that the proposed method has better robustness and positioning accuracy (about 0.1-0.2% travelled distance) than the traditional pedestrian navigation schemes do.