Robot bat has metal muscles

Posted by Emma Woollacott

Raleigh, NC - Tiny remote control planes and helicopters are all very well, but they lack maneuverability. But researchers at North Carolina State University are mimicking nature's small flyers, and developing robotic bats.

Small flyers, or micro-aerial vehicles (MAVs), have an enormous number of applications, from rescue missions to surveillance. "Due to the availability of small sensors, MAVs can be used for detection missions of biological, chemical and nuclear agents," says researcher Gheorghe Bunget at NCSU. But because of their size, devices using a traditional fixed-wing or rotary-wing design have low maneuverability and aerodynamic efficiency.

Looking to nature, the researchers decided that flapping flight was the most effective. And after analyzing bats' skeletal and muscular systems, they have developed a "robo-bat" skeleton.

The fully assembled skeleton rests easily in the palm of the hand and weighs less than six grams. The researchers are currently completing fabrication and assembly of the joints, muscular system and wing membrane for the robo-bat, which should allow it to fly with the same efficient flapping motion as real bats.

"The key concept here is the use of smart materials," Dr Stefan Seelecke said. "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."

The research team is also using smart materials for the muscular system. "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," said Seelecke. During the contraction, the 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," Seelicke explained.

In addition to creating a surveillance tool, Seelecke says the robo-bat could also help expand understanding of aerodynamics. "It will allow us to do tests where we can control all of the variables – and finally give us the opportunity to fully understand the aerodynamics of flapping flight," Seelecke said.