Intuitive ultrasonic INS augmentation for pedestrian path tracking and navigation

[Display omitted] •Pedestrian Inertial Navigation Systems (INS) suffer from long term stability issues.•Ultrasonic sensors provide valuable information on a small platform.•Combining ultrasonic sensor with an INS gives the ability to reconstruct walls.•Using wall information yields a reduction in error from 5.4% to 0.35% for 160 m walk.•After 400 m of walking, the final location error was 1.43 m from ground truth. In this paper, the benefits of augmenting an inertial navigation system (INS) with an ultrasonic sensor and an intuitive method of algorithmic correction are presented. An ultrasonic sensor was combined with a shoe-mounted INS allowing for the collection of information regarding wall location relative to the walked path. This information can be utilized to improve long term stability of the INS through the use of wall parallelism and perpendicularity corrections. Through the implementation of the correction methods herein, INS final location error was reduced from 5.9% to 0.35% of the total 120 m walked distance. During an experiment with 8-shaped path walking, peak error was reduced from 12.75 m to 1.22 m, a reduction in error of 90.4%. With long term INS stability being dependent on the ability of the gyroscopes to estimate heading rotation accurately, the correction method presented allows for the improvement of rotation estimation when the system is used in an indoor environment where wallscan be detected by the system.