A Pedestrian 3-D Position Estimation Method Based on Equality Constraint and Moving Platforms Correction Model

Inertial pedestrian navigation system (IPNS) has been broadly implemented for personnel navigation and positioning tasks without the preinstallation of infrastructure. However, the conventional foot-mounted IPNS that generally relies only on zero-velocity update (ZUPT) has serious heading drift and incorrectly judges foot as still phases when pedestrians take moving platforms (MPs; such as elevators and escalators). In this article, with the aid of six low-cost inertial sensors, a bipedal equality constraint method based on the Denavit–Hartenberg (DH) model is constructed to reduce heading drift. Then, an MP correction model that fuses detection, motion substates classification, and corresponding velocity constraint of MPs is proposed to achieve precise position tracking during elevator or escalator rides. Based on the equality constraint, the heading of the system is more accurate, which gives better play to the performance of the MP correction model. The robustness and effectiveness of the proposed algorithm are verified by multiple experiments in an office building, the positioning error in the rectangular 2-D experiment is less than 0.3%, and the horizontal positioning error and height positioning error in the comprehensive 3-D experiment are both less than 0.8%.