Autonomous takeoff, tracking and landing of a UAV on a moving UGV using onboard monocular vision

In this paper, we present a monocular vision based approach for cooperation between a micro unmanned aerial vehicle (UAV) and an unmanned ground vehicle (UGV). By tracking the target marker on the UGV, the UAV can autonomously track and land on the moving UGV. Closed control loops based on PID controllers are employed to accomplish two levels of control: low-level self-stabilized flight control, and high-level position control. The self-stabilized flight control is executed on an onboard microcontroller board with the aid of a 9-DOF inertial measurement unit (IMU). The images captured by the onboard low-cost camera are transmitted to the land laptop over wireless channels. The relative position of the UAV to the ground moving vehicle is estimated from the received images via a land laptop. The estimated current position is sent to the UAV via wireless channels. The proposed visual-based approach to detect and locate the target marker is robust to cluttered ground background as well as the height of the UAV. Practical experiments show that the UAV can autonomously track the moving UGV, and autonomously land on the landing marker on the moving UGV.