Robotic Bats as Next-Generation, Remote-Controlled Flyers

Emergency response teams and surveillance crews around the world already benefit from the advantages that remote-controlled flying probes have during an emergency situation, in a spot where humans cannot survive. But, while the machines have certainly made it a lot easier for their owners to respond to a situation, and to form an informed plan, there are still limitations to what they can do. Working to get past that problem, researchers at the North Carolina State University (NC State) have developed a new flying probe, shaped like a bat, and that flies pretty much in the same way as one.

The team boasts that its innovation benefits from increased maneuverability and performance, when compared to existing flying probes for civilian applications. NC State researcher Gheorghe Bunget explains that micro-aerial vehicles (MAVs) are of paramount importance when it comes to surveying tight space, where larger models would not fit, or would not have space to maneuver. “Due to the availability of small sensors, MAVs can be used for detection missions of biological, chemical and nuclear agents,” Bunget says, explaining why the team renounced the old design of fixed wings and rotary blades.

Not knowing where to start, Bunget, who is a doctoral student in mechanical engineering, and his advisor, Dr. Stefan Seelecke, again turned to nature for inspiration, and settled on the bat. “We are trying to mimic nature as closely as possible, because it is very efficient. And, at the MAV scale, nature tells us that flapping flight – like that of the bat- is the most effective,” Seelecke explains. “The key concept here is the use of smart materials. We are using a shape-memory metal alloy that is super-elastic for the joints. The material provides a full range of motion, but will always return to its original position – a function performed by many tiny bones, cartilage and tendons in real bats,” he continues.

At this point, the completed skeleton of the robo-bat is done, and it's about the size of an average palm. It weighs no more than six grams, but the experts say that its weight will increase slightly once the muscles, joints, and wing membranes are installed on it, together with observation equipment. “We're using an alloy that responds to the heat from an electric current. That heat actuates micro-scale wires the size of a human hair, making them contract like 'metal muscles,'” the researcher adds.

“During the contraction, the powerful muscle wires also change their electric resistance, which can be easily measured, thus providing simultaneous action and sensory input. This dual functionality will help cut down on the robo-bat's weight, and allow the robot to respond quickly to changing conditions – such as a gust of wind – as perfectly as a real bat,” he concludes.