An analysis of the zero-dynamics for visual servo control of a ducted fan UAV

A vision based control design to stabilise a ducted fan UAV equipped with a camera is presented. The proposed algorithm is motivated by recent work in image-based visual servoing control for under-actuated dynamic systems. In this paper, we show that the placement of the camera significantly affects the zero-dynamics of an under-actuated rigid body in a closed-loop image based visual servo control loop. We show that the zero-dynamics due to mechanical coupling of actuator forces can be cancelled in closed-loop by correct placement of the camera. This leads to improved robustness and performance of image based visual servo control design for small flying robots. The results are simulated on a model of ducted fan UAV to demonstrate the potential advantages.