f2IMU-R: Pedestrian Navigation by Low-cost Foot-Mounted Dual IMUs and Inter-foot Ranging
This work provides an incremental improvement in pedestrian navigation accuracy for applications in indoor or GPS-denied environments, benefiting fields such as medical monitoring, gait analysis, and first responder positioning.
This paper addresses the heading drift and accuracy limitations of foot-mounted inertial navigation systems by proposing a system that uses dual low-cost foot-mounted IMUs and inter-foot ultrasonic ranging. The proposed method achieves improved robustness and positioning accuracy, with errors of approximately 0.1-0.2% of the travelled distance, outperforming traditional pedestrian navigation schemes.
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.