Real time joint angle measurement method using multiple wearable sensors

Abstract

With the advent of wearable products, many wearable devices have come to the market that are trying to understand human behavior. A key challenge of this would be to understand human body motion as the human body can be modelled as an articulated system with complex joint movements. This paper contributes with a real-time joint angle measurement method with multiple wearable sensors using quaternions, which describes the orientation and rotation in 3D world. The study propose two approaches solving this: (1) quaternion vector rotation based joint angle calculation, (2) gravity vector based joint angle calculation. Each approach has its limitations and a real world application might be able to fuse both methods to get a reasonable output. In this method, we place multiple wearable inertial measurement units (IMU) in known locations of the body, calibrate them to remove errors of placement and calculate real time joint angles based on sensor outputs.