Washington State University has developed two insect-like robots, a mini-bug and a water strider, which are the smallest, lightest and fastest fully-functional micro-robots ever. Such miniature robots could someday be used for work in areas such as artificial pollination, search and rescue, environmental monitoring, microfabrication or robotic-assisted surgery.
Reporting on their work in the proceedings of the IEEE Robotics and Automation Society’s International Conference on Intelligent Robots and Systems, the mini-bug weighs in at 8 mg, while the water strider weighs 55 mg. Both can move at about 6 mm a second.
“That is fast compared to other micro-robots at this scale, although it still lags behind their biological relatives,” says Conor Trygstad, a PhD student at the School of Mechanical and Materials Engineering, and lead author. An ant typically weighs up to 5 mg and can move at almost 1 metre per second. The key to the tiny robots’ movement is their tiny actuators. Trygstad used a new fabrication technique to miniaturise the actuator down to less than 1 mg, the smallest ever known to have been made.
“The actuators are the smallest and fastest ever developed for micro-robotics,” says Nestor O Perez-Arancibia, Flaherty Associate Professor in Engineering at WSU’s School of Mechanical and Materials Engineering, who led the project. The actuator uses a material called a shape memory alloy that is able to change shapes when heated. It is called ‘shape memory’ because it remembers and then returns to its original shape.
Unlike a typical motor that would move a robot, these alloys don’t have any moving parts or spinning components, but are mechanically sound. Shape memory alloys are not generally used for large-scale robotic movement because they are too slow. In the case of the WSU robots, however, the actuators are made of two tiny shape memory alloy wires that are 1/1000 of an inch in diameter.
With a small amount of current, the wires can be heated up and cooled easily, allowing the robots to flap their fins or move their feet at up to 40 times per second. Compared to other technologies used to make robots move, the SMA technology also requires only a very small amount of electricity or heat to make them move.
(Source: Washington State University/Science Daily)