Autonomous Vision-based Tracking of UAV by a Flexible AGV*

Collaborative motion is one of the important phenomena of two agent UAV-AGV system during task execution. Tracking motion between UAV (Unmanned Aerial Vehicle) and AGV, landing of UAV over AGV (Autonomous Ground Vehicle) are fundamental collaborative tasks of the system. UAV is spatially omnidirectional, thus, trivial task to track the motion of AGV. However, AGV must be able to track UAV with the equal ease for effective navigation and overall agility of the system while performing missions. In this work, we explored the combination of 4WISD (4 Wheeled Independent Steering and Driving) vehicle and UAV to study the impact on collaborative motion of the system. Vision-based tracking of UAV by 4WISD ground vehicle is considered in this study to analyze the system. As 4WISD ground vehicles are expensive in the market from the research perspective, a low-cost 4WISD vehicle of 50Kg payload is designed and fabricated in the current research. ROS (Robot Operating System) based control package is developed to the ground vehicle. 4WISD vehicle is localized using low-cost monocular camera (attached to UAV) and a magnetometer sensor (integrated to 4WISD vehicle). Sliding mode control method is implemented for designing kinematic controller to 4WISD vehicle and verified using Lyapunov criteria. Tracking experiments are performed combining DJI Matrice600 (DJI M600), and 4WISD vehicle. Experimental results show the flexible tracking motion of AGV and indicate that combination of UAV and 4WISD may improve the collaborative motion of the system compared to the combination of UAV and non-holonomic AGV.