Learning-Based Complex Motion Patterns Recognition for Pedestrian Dead Reckoning

As the global navigation satellite system (GNSS) faces the problems of signals blocked by various objects and absorbed by many materials in indoor environments, many indoor positioning methods based on smartphones' inertial measurement unit (IMU) become increasingly applicable. Pedestrian dead reckoning (PDR) as one of the most universal methods, several algorithms with high accuracy have been proposed based on it. However, many algorithms are only applicable to scenes where pedestrians are in the “going forward” state. When the pedestrian's motions include complex patterns such as sidestepping and walking backward, PDR will not work normally as the estimated result is far from the real trajectory. In this paper, we design a deep learning model assisted PDR algorithm to recognize the pedestrian's complex motion patterns (going forward, walking backward, left sidestepping, right sidestepping) from the smartphones' IMU. We firstly employ one combined model of trained convolution neural network (CNN) and long short-term memory (LSTM) neural network to determine the correction angle for different motion patterns. Then, we estimate the pedestrian's motion direction by adding the correction angle to the attitude estimated by the inertial navigation system (INS) mechanization. Finally, the position can be computed by the estimated stride length and the corrected motion direction. Compared with different algorithms, the experimental results have proved that our algorithm can effectively process data in complex motion patterns.