Prio-IMU: Prioritizable IMU Array for Enhancing Foot-mounted Inertial Navigation Accuracy

This paper presents a prioritizable Inertial Measurement Unit (IMU) array, referred to as the Prio-IMU, which is a systematic approach to mitigate the problem of insufficient sensor's Full-Scale Range (FSR) and bandwidth, in the case of foot-mounted Inertial Navigation Systems (INS). The Prio-IMU integrates multiple IMUs with different sensor characteristics, aligns all the sensor measurements to a universal coordinate frame, and prioritizes the usage of each integrated sensor based on different scenarios. We developed a Prio-IMU prototype integrating two IMUs (ICM-20948 and ICM-20649) and a 3-axis accelerometer (ADXL375) and conducted a series of pedestrian navigation experiments involving walking and running. We observed that during the heel-strike phases of running activity, accelerometer and gyroscope measurements as large as 70 [gravity (g)] and 2600 [degree per second (dps)] could be picked up by the developed Prio-IMU prototype. The experimental results showed that the navigation accuracy of the Zero-velocity-UPdaTe (ZUPT)-aided INS using the proposed Prio-IMU was improved by 79% and 82% along the horizontal and vertical directions, as compared to the case of using a single IMU.