November 6th, 2012 by Michael Ricciardi
The field of biomimetics – the mimicking of biological attributes for practical uses — has become an increasingly important discipline in recent years, primarily due to its applications in other emerging fields like bio-engineering, materials science, and robotics.
An advance in robot locomotion – a big leap for tiny bots
In a recent robot prototype experiment conducted by Minkyun Noh and colleagues at Seoul National University *, South Korea, engineers were able to construct a tiny ‘flea-like’ robot (measuring just 2 cm in length) that leaps like the real thing; the ‘flea-bot’ utilizes a similar catapult bio-mechanism as a bio-flea uses to jump, but by using a different synthetic material — called nitinol — to act as the spring.
Nitinol is a ‘shape-memory’ alloy (SMA) material made of crystalline structures that allow it to switch between two conformations (positions) when it is subject to heating or an electric current. The synthetic substance mimics the flea’s endogenous, elastic protein resilin, which is compressed by a muscle in the flea’s upper leg, and locks it into place via latch-like tissue. Upon receiving a nerve impulse, a trigger muscle releases the latch, the resilin then rapidly decompresses, and launches the flea aloft.
A flea can jump more than 200 times its body length.
Slow priming and fast release
Noh’s team constructed three nitinol springs that lock/latch using a similar mechanism as in the flea’s leg. The mechanism is referred to as torque reversal triggering.
The bot’s body uses “a four-bar mechanism that simulates a flea’s leg kinematics with reduced degrees of freedom.” [source]
The “analog” nerve signal needed to release the latch, in this case, came via a wire attached to a separate power source. The bot’s nitinol springs were incrementally compressed, then, upon triggering the spring actuators (i.e., latch release), the bot was able to jump a distance of over 60 centimeters (two feet +) which is thirty times the flea-bot’s own length.
The next challenges for the team is to devise an “on-board” power supply (the bot is currently wired) and engineer it to be more stable during flight and upon landing. Both challenges will involve altering the design with the former probably adding to its weight (this prototype weights just 1. 1 gm), which, if using even miniaturized components, could limit its performance and jumping range.
However, new nano-scale batteries are in development and nano antennas (to receive a signal to make the bot jump on demand) have also been recently developed. These could be incorporated into the design without adding significant weight, leaving the stabilization of the flea-bots jump/landing the final engineering challenges here.
Watch the flea-bot’s big leap (article continues below)!
Fleas are members of the order Siphonaptera and feed off mammal and avian blood. They have been the bane of human (and animal) existence for as long as there have been humans, probably— spreading disease and discomfort wherever they land (they were the primary vector of the Black Plague in Europe).
But these robotic “fleas” – or their derivative / spin-off technologies – could find useful (even life-saving) applications in medicine, immunology, and bio-sensors, and, as a role-model: future micro-robots could wield micro drills and needles (for vaccines or sample taking) mimicking, in turn, the flea-bot’s bio-mimetic mechanics.
The robotics experiment was reported in the engineering journal (IEEE Transactions in Roboics, doi.org/jmb).
* School of Mechanical and Aerospace Engineering
Video: (source) Flea-like robot takes giant leap in bot locomotion by Paul Marks; Video courtesy of Minkyun Noh and colleagues at Seoul National University, South Korea
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