Designing a system for mobile manipulation from an Unmanned Aerial Vehicle

Due to their significant mobility advantages, UAVs have the potential to perform many tasks in locations that would be impossible for an unmanned ground vehicle to reach. However, most commercially available UAVs currently do not have the required lift to support high performance robotic arms. Recent advances in UAV size to payload and manipulator weight to payload ratios suggest the possibility of integration in the near future. Therefore, we seek to investigate and develop the tools that will be necessary to perform tasks when this becomes a reality. To emulate the UAV, we utilize a six degree-of-freedom gantry crane that provides the complete range of motion of a rotorcraft. Two seven degree-of-freedom manipulators attached to the gantry system perform grasping tasks. Computer vision techniques, including visual servoing, provide target object and manipulator position feedback to the control hardware. To test and simulate our system, we leverage the OpenRAVE virtual environment and ROS software architecture. Because rotorcraft are inherently unstable, introduce ground effects, and experience changing flight dynamics under external loads, we seek to address the difficult task of maintaining a stable UAV platform while interacting with objects using multiple, dexterous arms. As a first step toward that goal, this paper describes the design of a system to emulate highly dexterous manipulators on a UAV.