Measurement and Estimation of 3D Orientation using Magnetic and Inertial Sensors

Abstract

Magnetic and inertial sensors are becoming increasingly popular to measure three-dimensional (3D) orientation, because they are well suited to the ambulatory monitoring of posture and movements of subjects. This paper presents a complete implementation of the measurement and estimation of 3D orientation based on a magnetic and inertial measurement unit (MIMU) that we developed. The measurement unit was a combination of a 3D accelerometer, a 3D gyroscope, and a 3D mag-netometer. A Kalman lter-based sensor fusion algorithm was proposed to implement the measurements and 3D orientation es-timates. The accuracy of the orientation estimation, calculated by a sensor fusion algorithm, was assessed by comparison with a laboratory-bound optical measurement system. Several simulation experiments were executed to evaluate the performance of the measurement unit under various states, including static, periodically rotational, arbitrarily dynamic, and vibration states. Exper-imental results showed accurate and drift-free orientation estimates. The averaged root-mean-square errors (RMSE) of the roll, pitch, and yaw Euler angles in static state were ≤0.6. The averaged RMSE of the three angles in dynamic state or in dynamic tests at different angular velocities were ≤2.1, regardless of periodic rotations and arbitrary motions.