Measurement Accuracy of an Upper Limb Tracking System Based on Two Hillcrest Labs BNO080 IMU Sensors: An Environmental Assessment

Abstract

This paper presents an analysis on the accuracy of a two-IMU (Inertial Measurement Units) device. The device consists in two identical wired BNO080 sensors connected to a Central Control Unit, with the aim of developing a remote tracking tool for upper limb movements. The control unit collects the data from the sensors, ensuring the time synchronization, and retransmits the information to an external device. From the quaternions representing the orientation of the two sensors, the relative orientation can be calculated. A series of tests has been carried on using a robotic arm, allowing to perform repeated movements. Using this setup, the repeatability of the measurement, the accuracy and the measurement drift were then evaluated. The parameters were evaluated in conditions of variation of speed, position and acceleration compatible with those of a person. In a second stage, the sensors have been inserted into a wearable garment and used by a human in a real scenario, allowing the evaluation of possible sources of disturbance due to the environment, e.g. magnetic fields generated by electronic devices. The results show a good reliability of the relative orientation measurement, with an uncertainty generally smaller than 6 degrees per eulerian angle.