Standalone inertial pocket navigation system

Positioning applications became more important in recent years not only for security applications, but also for the mass market. Having a pedestrian navigation system embedded in a mobile phone is a realistic solution since it is equipped with low-cost sensors and the smartphone is located in a non-obstructive way. The location of the smartphone is important, since the position estimation process depends on it. Therefore, we propose to distinguish between pocket or bag, phoning, texting and swinging. We present a standalone inertial pocket navigation system based on an inertial measurement unit. For the computation of the orientation, we have developed an attitude estimator based on an unscented Kalman filter. The update stage has two different updates based on the acceleration and the magnetic field. Therefore, a zero acceleration detector, a magnetic disturbances detector and a static periods detector have been developed. The odometry in our navigation system is computed through an extended Kalman filter. The position is predicted with a movement model which is periodically updated through position corrections computed by the position computer. It comprises a step detector and a step length estimator based on the norm of the acceleration. The performance of our attitude estimator in comparison with the ground truth orientation is shown. The rest of the handheld positions are also tested for orientation. Likewise, we show pocket odometries of different users with the floor plan superimposed.