It doesn’t matter their cold, hard logic and tireless dedication to the task to be done – the most unpleasant aspect of the robots to come could be their personal hygiene.
In a demonstration of how to build machines that don’t overheat, the researchers created a robotic hand that adjusts its temperature naturally, breaking into a sweat.
The soft, moist appendage cools three times more effectively than a human being by secreting water on its “skin” when it is too hot. The water then removes the heat as it evaporates into the air.
The work aims to strengthen the resistance of robots that are in danger of overheating due to the repetitive nature of the jobs they do or because of the hot environments in which they operate.
“As often happens, biology has provided us with excellent guidance as engineers,” said TJ Wallin, a researcher who has joined Facebook since he worked on the project at Cornell University in New York. “It turns out that the ability to sweat is one of the most extraordinary characteristics of humans.”
While robots may be equipped with cooling systems similar to those found in cars, where water circulates in a closed circuit, researchers led by Robert Shepherd, a Cornell engineer, have sought a more natural solution to the problem of overheating.
The team focuses on soft robots, which can be more flexible, realistic and safer for humans to work with than traditional robots. But these advantages come at a cost, one of which the materials used are often less able to cope with large temperature changes.
The researchers used 3D printing to create synthetic fingers for the robot’s hand. Each finger is made up of a combination of “hydrogels” which contain about 50% water. The first layer of the finger is made up of a rigid hydrogel, while the second layer is made up of a more flexible one which contains superficial pores one fifth of a millimeter wide.
When your fingers are pressurized by pumping more water, they bend in a gripping motion. At low temperatures, the pores remain closed, but when the finger warms up, the pores expand and the hydrogel “sweats” to cool down. The surface of the finger is shaped to create a high surface, increasing the evaporation rate.
Tests showed that sweaty fingers cooled six times faster than fingers that had no ability to sweat in the presence of a ventilator. The robot hand had a cooling capacity of 107 watts per kg, more than three times that of humans and horses, two of the most effective sweaters in the animal kingdom.
“The best part of this strategy is that thermal regulatory performance is based on the material itself. We didn’t need to add sensors or other components to control sweat rates, “Wallin said. Further experiments showed that the sweaty hand could cool hot objects by collecting them and drawing heat from them.
While sweating helps keep your hand cool, the loss of water compromises your grip, as the water doubles as a hydraulic fluid. Another flaw is that sweat can make your fingers more slippery. These problems could be solved, Shepherd said, by increasing the hand’s water supply and adding further grip to the fingers.
Writing in Science Robotics, researchers describe how the sweating system could pave the way for robots that slip rather than walk, release fluids to clean themselves, and even digest and absorb nutrients.
The professor. Jonathan Rossiter, head of the light robotics team at Bristol Robotics Laboratory, said: “If future robots could be cooled naturally and automatically, they could work much better in a much wider range of environments. Humans can survive in the heat of the Sahara and in the freezing conditions of the Antarctic. Future robotics should be able to do the same.
“There is potential in this work to extend it to wearable devices and even” second skins “,” he added. “Of course, in the case of a second skin, one cannot wish for the robotic skin to generate too much sweat due to the social standards of sweating and personal hygiene.”