Since 2009, coin-scale robots with weighing only a few grams have been around when UC Berkeley presented its Robotic Autonomous Crawling Hexapod (RoACH), which is a 2.4gram hexapedal walker. A couple of years later, the Harvard Ambulatory MicroRobot (HAMR) decreased the number of legs to four and the weight of only 1.7 grams. Such small robots are very cool, but they are mostly fashioned to just exist, instead of testing the small robot dynamics.
To identify what gaits work finest for extremely small legged robots, Ryan St. Pierre formerly intended to consider a hexapod wheel-legged robot like RHex and reduce its dimensions. The benefit of utilizing a pattern like RHex is that each leg is independently manageable, making it convenient to experiment with an array of distinct gaits. But minute RHex did not work out well, because its legs tend to lock with each other, so Ryan cropped off the central pair, leaving a quadrupedal whegged robot.
At such sizes (each quadruped possesses a hip height of 5.6mm, weight of about 1.6 gram and length of 20mm), conventional batteries and motors are not going to reduce it. Rather, the robot is magnetically stimulated, utilizing an externally created magnetic field. Each of the four hips of the robot has a 2mm neodymium cube magnet inserted into it, and when a big magnet is rotated in closeness to the robot, the magnetic boost causes the little magnets to spin as well, rotating the legs of the robot.
By transforming the dipole orientation of the leg magnets in distinct combinations, you can move the robot with distinct gaits, including waddling, pronking, bounding and trotting. On the flat platform, a pronking gait stimulated at 10Hz resulted in a high average speed of about 78 mm/s, which is close to four-body lengths per second. Pronking also proved to be the finest gait for navigating mildly through terrain, although the terrain was rough, other gaits acted better.
“We have known that more dynamic gaits, where there is more plunging of the body as it loco mote, are more operative crossing over rough terrain, but are slower on flat terrain, “Ryan informed. “It is a surprising to know that there were some flight phases in few of the gaits, like pronking. It is this flight phase that aid gait in outperforming other gaits over the rough and flat terrain.”
Conclusion – It is a beautiful design that is convenient to mess with distinct gaits, different sorts of legs, or even varying structures for the robot. With the use of multi-material printers, this process becomes simple, and all these small robots can be pumped out at once. As per Ryan, it is a small-sized, 100 milligram quadruped that performs equally well like its elder brothers.