Toward coordinated manipulator-host visual servoing for mobile manipulating UAVs

Abstract

Manipulating objects using arms mounted to unmanned aerial vehicles (UAVs) is attractive because UAVs may access many locations that are otherwise inaccessible to traditional mobile manipulation platforms such as ground vehicles. Historically, UAVs have been employed in ways that avoid interaction with the environment at all costs. The recent trend of increasing small UAV lift capacity and the reduction of the weight of manipulator components make the realization of mobile manipulating UAVs imminent. Despite recent work, several major challenges remain to be overcome before it will be practical to manipulate objects from UAVs. Among these challenges, the constantly moving UAV platform and compliance of manipulator arms make it difficult to position the UAV and end-effector relative to an object of interest precisely enough for manipulation. Solving this challenge will bring UAVs one step closer to being able to perform meaningful tasks such as infrastructure repair, disaster response, law enforcement, and personal assistance. Toward a solution to this challenge, this paper describes an approach to coordinate the redundant degrees of freedom of an aerial manipulation system. The manipulator's six degrees of freedom will be visually servoed using an eye-in-hand camera to a specified pose relative to a target while treating motions of the host platform as perturbations. Simultaneously, the host platform's degrees of freedom will be servoed using kinematic information from the manipulator. This will drive the UAV to a position that allows the manipulator to assume a joint-space configuration that maximizes reachability, thus facilitating the arm's ability to compensate for undesired UAV motions without the need for an external pose estimation system.