Quaternion based pointing algorithm for two-axis gimbal of micro aerial vehicles

With the increased use and demand of Unmanned Aerial Vehicle (UAV) and Micro Aerial Vehicle (MAV) for military, societal, security, coast guards, surveillance, entertainment etc., MAVs demand precision payload with well stabilized and controllable gimbal system. The fidelity of the data is directly dependent on the degree of control of the gimbal. Hence an efficient gimbal controller plays an important role in the success of the UAV/MAV mission. This paper uses unit quaternions for rotations and derives an algorithm to point a camera, mounted with a two-axis (roll-pitch) gimbal on a Micro Aerial Vehicle (MAV), towards a target at a known location on the ground. The use of unit quaternions makes the algorithm more computationally efficient and free of mathematical singularities. The inputs required are the GPS coordinates of the MAV and the target along with the attitude information of the MAV measured using Inertial Measurement Unit (IMU). The algorithm calculates the gimbal roll pitch angles required to point the camera at the target.