Pheromone Robots
Create a Buzz


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Silk moth driving robot. Image: www.thinkstockphotos.com

What helps the beehive hum, the ant-hill hop, and the silk moth land a mate? Pheromones, of course, nature’s biochemical signaling system for creating order in the insect kingdom. Lately, the buzz about pheromones has spread beyond the bug world into several key areas of technology. Engineers and biologists are cracking the pheromone code, copying insects’ complex chemical semaphore system for human-scale applications in robotics, defense, telecommunications, and agriculture.

The term pheromone was coined in the late 1950s to describe hormone-like substances that work outside an organism’s body to stimulate a response from other members of its species. In nature, insects and a few vertebrates and plants secrete pheromone markers into a shared physical environment. These chemical messengers act on the autonomous nervous system of the receiver, triggering physiological changes that alter behavior. Insects use pheromones for mate-selection, to warn of danger, to mark routes to food sources, and to organize group tasks such as nest-building. As a result, groups of insects work in harmony to achieve complex goals without the need for direct communication, which experts call “stigmergic” interaction. These principles have been applied to the study of group behavior at every scale from mites to man. Their data provide the computational platform for technologies that bring pheromone-fired efficiency to environments ranging from warships to the warehouse.

Navy ordnancemen transporting bombs onboard aircraft carrier. Image: U.S. Navy

Bots for Bombs

The U.S. Navy sees a future for pheromone-sniffing robots onboard its next-generation aircraft carriers. In a 2013 research proposal, the Navy asked potential contractors for help in developing technologies to automate the expensive and personnel-intensive job of getting bombs out of storage in the ship’s bowels and on to the bombers parked on the flight deck. Currently the job is handled by a corps of sailors known as red shirts, who team up to move and transfer bomb-laden skids from the ship’s weapons cache through the narrow corridors and multiple elevators en route to the flight deck. It takes three to six red shirts per skid to move these heavy, dangerous weapons, adding some 80 sailors to each carrier crew.

The Navy is eyeing a tech alternative inspired by the insect world’s leader-follower system of organization. Under the control of a human, a lead robot would deposit an artificial chemical pheromone marker along a route to the flight deck. A mini-armada of subordinate units bearing a bomb-laden skid would follow the trail using chemical-sniffing sensors to find each successive marker and individually analyze and interpret its next instruction.

The concept is the olfactory counterpart to the optical scanning-based order fulfillment system developed by Amazon.com subsidiary Kiva Systems (North Reading, MA). Companies like Zappos.com and the Gap use the system to reduce the time and increase the efficiency of the order processing cycle on the warehouse floor. Instead of making humans wander around a labyrinth of aisles looking for a specific shelf holding product X, the system makes a swarm of squatty orange robots bring product X’s shelving unit right to the human order processor. Kiva’s robots follow trails of optical “pheromone” markers on the floor.

Insect-controlled robot. Image: University of Tokyo

Moth Mimickery

For pheromone purists, however, there’s nothing like the real thing. A group of University of Tokyo researchers went straight to the source to study the neurochemical call of the wild. One of nature’s most-studied pheromone tracking phenomena is the complicated courtship ritual of the male silk moth. When stimulated by female pheromones, the male approaches the potential mate in a characteristic dance-like pattern. Lead scientist Noriyasu Ando believes the moth’s brain mechanics during this ritual may hold the key to future artificial autonomous systems.

In work published in the journal Bioinspiration and Biomimetics, Ando’s team harnessed a male moth to a polystyrene ball attached to robotic controller. In response to female pheromones emitted by the device, the moth’s movements caused the ball to move computer mouse-style through the steps of the mating dance. Researchers then introduced unexpected variations such as uncharacteristic changes in direction or delays in the delivery of pheromone to force the moth to adapt. Measuring the odor-tracking behavior at the level of the individual neuron, Ando said, will help researchers build future adaptive systems that work the same way.

Automation technology has come of age, and it’s only natural that robots have learned about the birds and bees. Robots that think like bugs are at the opposite end of the technology spectrum from the traditional automatons that move and multi-task like people. But the mechanics of the human form don’t work in many situations. Advanced sensing technologies provide engineers with mechanical alternatives that perform complex tasks that more intelligent and expensive robots can’t do.

Michael MacRae is an independent writer.

Automation technology has come of age, and it’s only natural that robots have learned about the birds and bees.

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May 2014

by Michael MacRae, ASME.org