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Festo creates a buzz at Hannover with its swarming bionic bees
At the Hannover Messe, Festo unveiled the latest in a long line of bionic versions of living creatures – this time, a bionic bee which weighs around 34 grams, is 220mm long and has a 240mm wingspan, making it the smallest flying object created so far by Festo’s Bionic Learning Network. The bees can fly in large numbers and move autonomously in swarms, following paths specified by a central computer.
The bee’s body houses a wing-beating mechanism, including a brushless motor, three servomotors, a battery, gearbox and various PCBs, as well as communications technology. Intelligent interaction between the motors and the mechanics means that the frequency of the wing beats can, for example, be adjusted to perform precise manoeuvres.
The artificial bee flies with four degrees of freedom and a wing beat frequency of 15–20Hz. The brushless motor drives the wings without backlash via an ultra-light mechanism so that they beat backward and forward at a 180-degree angle. The higher the motor speed, the higher the beat frequency and the lift. The three servomotors at the base of the wings alter their geometry, thus increasing the effectiveness of certain wing positions and generating variations in lift.
For the bees to fly forward, the geometry is adjusted so that the lift in the rear wing position is higher than that in the forward position. This causes the body to tilt forward. If the geometry is adjusted so that the right wing generates more lift than the left wing, the bee rolls around a longitudinal axis to the left and flies to the side. Another option is for one wing to generate more lift at the front, and the second to generate more lift at the rear, causing the bee to rotate (yaw) around a vertical axis.
The BionicBee’s autonomous swarming behaviour is achieved using an indoor location system based on an ultra-wideband (UWB) technology. Eight UWB “anchors” are installed on two levels, enabling accurate time measurements and allowing the bees to locate themselves precisely in space. The UWB anchors send signals to each bee, which measure the distances to the transmitters and calculate their spatial position using the timestamps.
To ensure safe, collision-free flight in close formation, high spatial and temporal accuracy is vital. When planning the bees’ paths, possible interaction between them caused by air turbulence “downwash” has to be taken into account.
Each bee is handmade and the smallest manufacturing differences can influence its flight behaviour. Each has an automatic calibration function: after a short test flight, it determines its own optimised control parameters. An algorithm calculates the hardware differences between the individual bees, allowing the entire swarm to be controlled from outside, as if all were identical.
The BionicBee is the latest creation from Festo’s Bionic Learning Network which, for more than 15 years, has been fascinated by flight, with previous airborne creatures including bionic butterflies, flying foxes, gulls and swifts. There have also been aquatic critters including swimming sharks, cuttlefish, jellyfishes and octopi, as well as mechatronic versions of land-based animals including ants, kangaroos, chameleons, spiders and elephants.
For the first time, the developers used generative design techniques to create the BionicBee. After entering a few parameters, a software application determined the optimal structure to use as little material as necessary while maintaining the most stable performance. This lightweight construction was essential to achieve the bee’s manoeuvrability and extended flying times.
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