Attaching a platform to a high-rise building to evacuate people in an emergency, or creating a landing stage for an aircraft on uneven terrain - these are just two areas in which flying robots could have a huge impact - potentially saving lives.
The ARCAS ('Aerial Robotics Cooperative Assembly System') team is 18 months into a 4-year project to develop such machines. The team is working on the first-ever cooperative free-flying robot system able to assemble and construct structures in inaccessible sites, including in space.
Advances in five key areas are needed to get the robots up and flying: the helicopters or quadrotor systems themselves, motion control for transportation and assembly; robot perception; cooperation between multiple robots; and tools to allow human intervention.
The team has already developed prototypes. The first is a quadcopter with a robotic arm and a 'hand' designed to grasp cylindrical objects. Keeping the arm's weight as low as possible was a priority; the result is minimal impact on the quadcopter's stability.
The second prototype is an electrical helicopter fitted with a gripper mounted on an arm able to bend in any direction.
Each robot will be equipped with a manipulator able to grasp objects. The team is working on motion control techniques for this manipulator, which must include coordinating the control of multiple flying robots grasping the same object during a construction task.
Perception is key to any task-oriented robot. For the ARCAS robots, this includes scene recognition, fast 3D model generation, simultaneous localisation and mapping by multiple aerial robots, accurate 3D positioning and tracking so that assembly operations can be guided, and cooperative perception for assembly - the robots must be able to work together.
Cooperative planning will ensure safety during the simultaneous operation of multiple flying robots during assembly, disassembly or inspection tasks, while human operators must be able to intervene in this autonomous perception, planning and control when necessary. They will do this using virtual reality haptics - technology operated through touch.
Once the concepts, methodologies and algorithms are in place, they will be tested in three different ways. Autonomous quadrotors and an integrated system for positioning will assessed for basic manipulation and assembly functions. These tests will take place indoors. More advanced manipulation devices with integrated force sensors mounted on autonomous helicopters will be tested outdoors. And multiple robot arms will be used to simulate free-flying objects manipulating objects in space.
The project is expected to lay the foundations for designing and developing cooperating flying robots with various physical characteristics that could be used in a range of applications. ARCAS' industrial partners will be the first to adopt the project's technologies, providing a path to commercialisation, whether in inspection, maintenance, repair, satellite servicing or structure construction.
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