On the attitude estimation of accelerating rigid-bodies using GPS and IMU measurements

We present two observers that estimate the orientation of a rigid body, which is subjected to linear accelerations and rotational motion, using a global positioning system (GPS) and a body-attached inertial measurement unit (IMU). Unlike some other attitude estimation schemes (which assume that the accelerometer measures the gravity vector, which is not realistic when the rigid body is subject to large linear accelerations), the proposed results belong to the special class of velocity-aided attitude observers, which instead use the true accelerometer measurements (i.e., the system´s apparent acceleration). The linear velocity of the rigid body (obtained from the GPS) is used to obviate the requirement of the linear acceleration (which is assumed unavailable in the inertial frame). The new observers can handle large accelerations of the rigid body which could otherwise destroy the performance of other types of attitude observers which assume that the accelerometer measures the gravity vector.