Development of High Rate Wearable MIMU Tracking System Robust to Magnetic Disturbances and Body Acceleration

In this paper we present a wearable high rate MIMU (magnetic-inertial measurement unit) based body tracking system. It is designed using low cost state-of-the-art hardware and MEMS sensors to reduce errors and improve computational latency. Our system allows for high rate data acquisition and sensor fusion at low power budget. It can be used for range of applications from extreme activity capture and biomechanical analysis to clinical evaluation and ambulatory health monitoring/rehabilitation. The package size of sensing nodes is small, and we use textile wires which make it very flexible. Thus entire system can be easily integrated with body worn suit/pants. Up to 7x nodes can be connected without compromising the maximum sampling frequency (1 kHz), with the possibility to add more nodes using additional bridge stations between nodes. The acquisition rate can be preset from 1 kHz to 100 Hz to suit the application or accuracy requirements. To the best of our knowledge, our inertial motion capture system is the first to offer such high rate output at 1 kHz for multiple nodes. The high rate of inertial data provides intrinsic accuracy to sensor fusion as well as capture high frequency features for clinical diagnostics and biomechanical analysis in ambient settings. The system also runs an embedded sensor fusion algorithm for accurate orientation estimation. We introduce a novel accelerometer and magnetometer measurement correction with adaptive sensor covariance approach in EKF, which makes it robust to both magnetic disturbances and body accelerations. Thus it is well suited for indoor human motion analysis and monitoring highly dynamic motion.