The ground truth of the orientation is captured by the vicon and is present in the vicon folder. The IMU datasets is present in the imu folder. estimate_rot.py tracks the orientation using the IMU data and UKF.
E. Kraft, "A quaternion-based unscented Kalman filter for orientation tracking," Sixth International Conference of Information Fusion, 2003. Proceedings of the, Cairns, Queensland, Australia, 2003, pp. 47-54, doi: 10.1109/ICIF.2003.177425.