Holding-Manner-Free Heading Change Estimation For Smartphone-Based Indoor Positioning

Smartphones have been a great platform for location-based services (LBS) and heading estimation is a key technique. In this paper, we proposed a heading change estimation algorithm based on inertial sensors built-in smartphones for indoor positioning. Compared with previous common approaches, it gives the users a larger freedom, not requiring fixed even specific holding manners. The algorithm consists of three main parts, including holding manner transition detection, equivalent vertical angular update and heading change calculation. Holding manner transition detection aims to separate the gyroscope measurement contribution caused by transitions from that of the user's heading change. Equivalent vertical angular rate is defined to recognize the heading change interval. Due to the low-precision of inertial sensors, heading change is calculated by tracing the ideologies of complementary filter and inertial frame alignment. It can also be obtained from the equivalent vertical angular rate directly for low accuracy requirement situation. In the case of known initial heading, the proposed method is converted to a heading estimation method. Experiment results show that the proposed method can detect the holding manner transition accurately and provides relatively good heading change estimation.