Scientists develop more quieter robot

A team of robotics engineers from University of Nevada in Reno have developed a system that makes pneumatic artificial muscles much quieter than before.

Annoying noise produced by air pumps or electric motors in human-like robots is among the factors hampering their entry into consumer market. Researchers came up with an idea how to make artificial muscles work silently.

Metal hydrides can undergo a process called reversible chemisorption, allowing them to store and release extra hydrogen held by weak chemical bonds. It's this property that has led to the motor industry investigating metal hydrides as hydrogen "tanks" for fuel cells.

To make a silent artificial muscle, Kwang Kim and his colleague Alexandra Vanderhoff first compressed a copper and nickel-based metal hydride powder into peanut-sized pellets. They then secured them in a reactor vessel and pumped in hydrogen to "charge" the pellets with the gas. A heater coil surrounded the vessel, as heat breaks the weak chemical bonds and releases the stored hydrogen.

The next step was to connect the vessel to an off-the-shelf artificial muscle, which comprises an inflatable rubber tube surrounded by Kevlar fibre braiding. Two of these placed either side of a robotic joint can mimic the push/pull action of muscles by being alternately inflated and deflated (see diagram).

Turning the heater on and off controls the flow of hydrogen into the rubber tube, causing the muscle to move silently. Even better, the pair say, the muscle performs as well as those that run on compressed air systems. Importantly, the gas didn't leak.

"The system has biological muscle-like properties for humanoid robots that need high power, large limb strokes - and no noise," says Kim.

Source - Newscientist



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