  Inertial navigation systems for pedestrians are infrastructure-less and can
achieve sub-meter accuracy in the short/medium period. However, when low-cost
inertial measurement units (IMU) are employed for their implementation, they
suffer from a slowly growing drift between the true pedestrian position and the
corresponding estimated position. In this paper we illustrate a novel solution
to mitigate such a drift by: a) using only accelerometer and gyroscope
measurements (no magnetometers required); b) including the sensor error model
parameters in the state vector of an extended Kalman filter; c) adopting a
novel soft heuristic for foot stance detection and for zero-velocity updates.
Experimental results evidence that our inertial-only navigation system can
achieve similar or better performance with respect to pedestrian dead-reckoning
systems presented in related studies, although the adopted IMU is less accurate
than more expensive counterparts.
