Flying insects - flies, bees, dragonflies and mosquitoes - easily slip through narrow gaps and do not break when they hit obstacles. Flying robots, by contrast, often fall and break on contact with surfaces. Researchers from the University of California, Los Angeles (UCLA) and the University of California, Davis (UC Davis) have presented a tiny robot that better replicates the resilience of insects. The work was published in the journal Science Robotics.
The robot weighs just 185 milligrams - less than a fifth of a gram. It is made entirely of polymers - materials consisting of long chains of linked molecules. The design combines a soft "muscle" driven by electricity and flexible cone-shaped wings. Unlike many miniature robots, there are no fragile mechanical gears here: the polymer film itself bends rapidly and directly flaps the wings.
The wings' "muscle" is a thin film of relaxor ferroelectric polymer. Under an electric field the material expands - a phenomenon called electrostriction, and it is reversible. The scientists use this motion to create powerful flaps with a very fast response. The asymmetric aerodynamic shape and partial deformation of the wings on each flap allow lift to be generated, while flexibility helps the wings bend on contact. The wing material is not prone to creasing, which increases impact resistance.
The first prototype was powered by external wires. In tests the robot lifted off the ground on its own, rising at an average speed of 40 centimeters per second, and generated lift three times its own weight. It also resumed flight after being struck by a flyswatter and after being flattened by a heavy weight.
The authors emphasize that this is still a laboratory prototype, not a finished product. In the future they plan to add an onboard power source, control electronics and sensors. The next tasks are to improve flight control, including turning and landing, and to increase the payload. In the longer term, the robot is to be tested for environmental monitoring, pollination in agriculture and search-and-rescue operations. This will require further refinement, but impact resistance could become an important step toward reliable operation in real-world conditions.