Estimation and Tracking of Knee Angle Trajectory using Inertial Sensors and a Smartphone Application

Abstract

We demonstrate a practical solution to track the 2-D knee angle trajectory of a user in real-time using inertial sensors embedded in a wearable knee-band wirelessly coupled with a mobile device, by mathematically modeling the knee as a hinge joint. We show how the bias of gyroscopes can be automatically computed to eliminate manual calibration and combined with a computationally simple Kalman filter model for tracking the knee-angle on a power constrained mobile device. Finally, we visualize the 2-D knee motion trajectory in real-time using an avatar on an Android phone.

Keywords

• android
• flexion angle
• motion tracking
• state estimation