December 5, 2013
Robotics Engineers Study Cockroaches For Sensor Design
Brett Smith for redOrbit.com - Your Universe Online
Robotics engineers have been increasingly turning to nature for inspiration recently, and a team from the University of California, Berkeley and Johns Hopkins University has studied the antennae of cockroaches to develop a system that uses locomotion as a means of controlling the position of a passive sensor, according to their report in The Journal of Experimental Biology.The researchers said they were inspired by observations of cockroach antennae bending as the insects run, which they do to prevent crashing into walls. According to study author Jean-Michel Mongeau, the positioning of the antennae may be more of a result of passive forces than the cockroaches’ nervous system.
“'When animals move slowly they rely mostly on their nervous system for accomplishing tasks, but as the animals are pushed to more extreme performances they face potential constraints in their nervous system, for example sensory conduction delays,” explained Mongeau, a researcher at UC Berkeley.
In the study, the researchers placed blind cockroaches into an arena that was filmed by two high-speed cameras. A gentle prod from a researchers sent the cockroaches scurrying along a wall with a 30 to 60 degree bend in the middle. The cockroaches' antennae often projected out straight as they tracked along a smooth acrylic wall. However, the antennae acted differently on a wooden wall.
“When the wall becomes rougher, which you could think of as more ecologically relevant for this animal, the antenna would bend backwards almost all of the time, in a sort of inverted J-shape,” Mongeau said.
After measuring the body-to-wall distance, the researchers realized that the bending of the antenna caused the cockroaches to position themselves further away from the wall and prevent them from crashing into it, unlike the cockroaches with straight antennae.
“After these findings, we became interested in understanding the mechanism behind the antenna changing shape,” Mongeau said. “We hypothesized that very tiny tactile hairs on the antenna would potentially be able to engage with, and stick to, (a rough) surface, and when that is coupled with forward motion this would be sufficient to make the antenna flip.”
To test their theory, the team chose to remove these little tactile hairs – a process that turned out to be more difficult than it would have seemed.
“The first thing I tried to do was use tiny forceps to pluck the hairs out, but that turned out to be impossible because these hairs are very robust and they're embedded within the exoskeleton,” Mongeau said. “After going through several rounds of trial and error, or mostly error, I decided to try a laser system that burns these little hairs at the tip.”
After performing the laser hair removal, the hairless antennae rarely bent backwards, even as they were dragged along a wall.
The team then applied their findings to a robotics design and found they were able get their artificial antenna to bend in a similar fashion. The researchers also noted that a slight change to the orientation of the hairs can cause the antenna to fully curl over into an inverted C, making the antenna useless.