A common method for creating a 6 degree of freedom (DoF) device is to track a single marker with a camera to measure linear position, and use an IMU to measure angular position (orientation). This is often used for AR and VR controllers and head tracking. One key challenge is aligning the coordinate frames of the camera and the IMU, and keeping them aligned over time. This paper presents a method of frame alignment that doesn’t require user intervention, and properly handles integration errors from the gyroscope as well as the very large errors encountered when performing double integration on the linear acceleration of the IMU’s accelerometer to compute linear position. The paper also compares two options for solving for the alignment, either a recursive least-squares (RLS) approach or as a solution to Wahba’s problem.
