Harvard PhD removes the last "hard bone" in soft robots and a flexible computer is born

Introduction

In recent years, soft robots have developed rapidly, and they can't wait to remove the "hard bones" in their bodies - metal parts. On this road to removal, Preston, a postdoctoral fellow from Harvard, has made a flexible computer, which not only removes the "bones" but also hopes to make soft robots programmable.

Author: Wind and Rain

Editor: Aliey

A soft robot, attached to a balloon and submerged in a clear column of water, dives and then comes up, then dives and surfaces again, like a fish chasing a fly. This isn't a complicated trick for existing soft robots, but unlike most soft robots, this one was built and operated without hardware or electronics.

In this robotic system, a flexible rubber computer tells the balloon when to rise or fall. This is the first robot to rely entirely on soft digital logic.

Over the past decade, soft robots have flooded into a field dominated by metal. Grippers made from rubbery silicone materials are already used on production lines: Cushioned claws grab fruits and vegetables such as tomatoes, celery and sausages.

And in the lab, grippers can pick up slippery fish, live mice and even insects, allowing people to complete more tasks.

Soft robots require simpler control systems than hard robots. This is mainly because the grippers are so soft that they can't generate too much pressure to damage the object, so there is no need to calibrate the pressure, and simply turning on and off is enough. But so far, most soft robots still rely on some hardware: metal valves, rubber grippers, and air channels for the arms.

Now, researchers have built a soft computer out of rubber and air.

"We are mimicking the thought process of an electronic computer, using only soft materials and pneumatic signals, replacing the electronics with compressed air," said Daniel J. Preston, first author of the PNAS paper and a postdoctoral researcher with George Whitesides.

Preston's soft computer simulates this system using silicone tubing and pressurized air. To implement the minimum types of logic gates needed for complex operations - NOT, AND and OR, he programmed the soft valves to react to different air pressures. For example, for the NOT logic gate, if the input is high pressure, the output is low pressure. Preston said, " With these three logic gates, you can replicate any behavior on any electronic computer." This is obviously another application of Turing's profound ideas.

For example, a floating fish-like robot in a water tank uses an ambient pressure sensor (a modified NOT gate) to determine what action to take.

When the circuit senses the high pressure at the top of the tank, the robot dives

When sensing high pressure at depth, the robot rises.

If someone presses an external soft button, the robot can also execute the corresponding command.

There are several benefits to robots built with only soft parts. In an industrial setting, large metal machines may not slow down enough to hit a human, which could cause serious injury if it were a metal robot. But if a soft robot hits a person, it might just be a massage. And it's not just safer: Soft robots are often cheaper, simpler, lighter, and resistant to damage and corrosive materials.

For aluminum, sodium hydroxide is hospitable and allows you to blend with it

For our soft robots, it is obviously better

After being programmed, the robot can sense the user's temperature and give a soft squeeze to indicate a fever, alert divers when water pressure rises too high, or clear the rubble after a natural disaster to help find victims. Soft robots can also be used in the study of electronic devices: for example, the high radiation fields after a nuclear failure or the radiation fields generated in outer space, and the inside of a magnetic resonance imaging (MRI) machine. Or after a hurricane or flood, a "strong" soft robot can manage dangerous terrain and harmful air.

“If it gets run over by a car, it keeps going, which is hard to do with a hard robot,” Preston says. (Unless you’re really hard.) ” Preston and his colleagues aren’t the first to control robots without electronics. Other research teams have designed microfluidic circuits that use liquids and air to create nonelectronic logic gates. However, microfluidic logic circuits typically rely on hard materials like glass or hard plastics, and they use channels so thin that only a small amount of air can pass through at a time, slowing the robot’s movement. Preston’s channels, by contrast, are larger in diameter—nearly 1 millimeter—which allows the air to flow faster.

His air gripper can grab an object in seconds. Microfluidic circuits are also less energy efficient. Even when at rest, these devices use pneumatic resistors, which move air from the atmosphere to a vacuum or pressure source to keep them stationary. Preston's circuit requires no energy input when dormant. Such energy savings are critical in emergency or disaster situations where robots are far from a reliable energy source.

The rubber robot also offers a tantalizing possibility: invisibility (perhaps cribbed from jellyfish). Depending on the material Preston chooses, he can design a robot that indexes to match a specific substance. So if he chooses a material that camouflages itself in water, the robot will appear transparent when submerged. In the future, he and his colleagues hope to create autonomous robots that are invisible to the naked eye or even detectable by sonar.

Obviously, this idea is very interesting. It is based on the aerodynamic principle and uses discrete air pressure to achieve computerization. However, I don’t know whether the idea can be realized.