Dual-foot navigation system with ultrasonic ranging and elliptical constraints for reliable position estimation

A novel pedestrian navigation system (PNS) is proposed that integrates dual-foot inertial measurement units (IMUs), ultrasonic inter-foot ranging, and biomechanical elliptical constraints within an Extended Kalman Filter (EKF) framework. This system overcomes the drift and error accumulation challenges commonly encountered in traditional inertial navigation methods, particularly in GPS-denied environments. Incorporating an adaptive elliptical gait constraint improves estimation accuracy by modeling the spatial relationship between the feet and mitigating positional drift. The EKF framework efficiently combines foot-mounted IMU data with ultrasonic ranging measurements to deliver accurate and reliable localization estimates. Experimental results show that the proposed method significantly reduces localization error, achieving an average error of only 2.77% (300m) in long-distance closed-loop tests, marking a substantial improvement over existing methods such as ESKF+ZUPT and KF.