6 June/July 2024 | Uncrewed Systems Technology Mission-critical info for uncrewed systems professionals Platform one Festo has developed a miniature bee that can fly autonomously in a swarm, writes Nick Flaherty. The BionicBee is the first flying object developed by the team at Festo, and it can fly completely autonomously in large numbers and as part of a swarm. The bee weighs 34 g and is 22 cm long with a wingspan of 24 cm. It was created with a generative design method: after entering a few parameters, the software finds the optimal structure to use as little material as necessary to create the most stable design possible. This consistent, lightweight construction is crucial for good manoeuvrability and flight duration. The body forms the compact housing for the beating-wing mechanism, the communication technology and the wing’s control components. These are driven by a brushless motor, three servo motors, battery, gear unit and printed circuit boards. The brushless motors drive the wings with a beat frequency of 15-20 Hz at a 180o angle without backlash using a precisely guided, ultra-light mechanical construction. The three servo motors at the base of the wing change its geometry to steer the bee by increasing the effectiveness of certain wing positions and generating a specific variation of lift. If the bee is supposed to fly forwards, the geometry is adjusted so that the lift in the rear-wing position is greater than in the forward. This causes the body to tilt forwards (pitch) and the bee flies forwards. If the geometry is adjusted so that the right wing generates more lift than the left wing, the bee rolls around the longitudinal axis to the left and flies off to the side. Another option is to adjust it in such a way that one wing generates more lift at the front and the second wing generates more lift at the rear, which causes the bee to rotate (yaw) around the vertical axis. The autonomous behaviour of the 10 bees is enabled by an indoor localisation system with ultra-wideband technology (UWB). Eight UWB anchors are installed at two levels within the volume of space where the swarm operates, and they send signals to the individual bees, which independently measure the distance to the transmitters and can calculate their own position using the timestamps. To fly in a swarm, the bees follow the paths specified by a central computer. Spatial and temporal accuracy is required for collision-free flight in close formation. The bees have an automatic calibration function, so that after a short test flight, each one determines its own optimised controller parameters. This is how the intelligent algorithm can work out the hardware differences between the bees and enables the entire swarm to be controlled externally as if they were all identical. Uncrewed aerial vehicles Autonomous robot makes beeline in a swarm The BionicBee (Image courtesy of Festo)
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