@article {2012q-FraMasGraRylBueRob, title = {Modeling and Control of UAV Bearing-Formations with Bilateral High-Level Steering}, journal = {The International Journal of Robotics Research, Special Issue on 3D Exploration, Mapping, and Surveillance}, volume = {31}, year = {2012}, month = {10/2012}, pages = {1504-1525}, abstract = {In this paper we address the problem of controlling the motion of a group of UAVs bound to keep a formation defined in terms of only relative angles (i.e., a bearing-formation). This problem can naturally arise within the context of several multi-robot applications such as, e.g., exploration, coverage, and surveillance. First, we introduce and thoroughly analyze the concept and properties of bearing-formations, and provide a class of minimally linear sets of bearings sufficient to uniquely define such formations. We then propose a bearing-only formation controller requiring only bearing measurements, converging almost globally, and maintaining bounded inter-agent distances despite the lack of direct metric information. The controller still leaves the possibility to impose group motions tangent to the current bearing-formation. These can be either autonomously chosen by the robots because of any additional task (e.g., exploration), or exploited by an assisting human co-operator. For this latter {\textquoteleft}human-in-the-loop{\textquoteright} case, we propose a multi-master/multi-slave bilateral shared control system providing the co-operator with some suitable force cues informative of the UAV performance. The proposed theoretical framework is extensively validated by means of simulations and experiments with quadrotor UAVs equipped with onboard cameras. Practical limitations, e.g., limited field-of-view, are also considered.}, keywords = {Bilateral Shared Control of Mobile Robots, Decentralized control, Force feedback, Formation control, Haptics, Motion control of multiple robots, Multi-robot systems, Teleoperation}, attachments = {https://homepages.laas.fr/afranchi/robotics/sites/default/files/2012q-FraMasGraRylBueRob-preprint.pdf}, author = {Antonio Franchi and Carlo Masone and Volker Grabe and Markus Ryll and Heinrich H. B{\"u}lthoff and Paolo Robuffo Giordano} }