These insect-inspired robots are made from drinking straws

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Automation is the future. Robots are a means to achieve it. There are robots made of metals. However, there are applications which need something softer. That is where soft robots come into the picture. For the uninitiated, this sub-field deals with 'constructing machines from highly compliant materials, similar to those found in living organisms.' Harvard has taken a step further and developed robots from drinking straws. Needless to say, they are inspired by insects.

Soft robots from Harvard are made from drinking straws

The semi-soft robot developed by the team is capable of standing and walking. There is also a robotic water strider which can move along the surface of the liquid.

“If you look around the world, there are a lot of things, like spiders and insects, that are very agile,” said George Whitesides, the lead researcher. “They can move rapidly, climb on various items, and are able to do things that large, hard robots can’t do because of their weight and form factor. They are among the most versatile organisms on the planet. The question was, how can we build something like that?”

They began by making the plastic straws bendable by cutting a notch in them. In the second step, short tubes were inserted into those notches. Rubber strips were attached on either side to act as tendons. As a result, the inflated tubes extended the joints, and in deflated state the rubber retracted them, thus creating a moving mechanism.

The above resulted in a simple one-legged robot capable of crawling. The team then began to increase the complexity by adding more legs. Two legs made the bot capable of pushing and pulling itself, and yet another leg resulted in a robot capable of standing on its own, just like a tripod. At the sixth level, the team as able to achieve a gait similar to that of an ant. By the time they reached to eight levels of complexity, making the bots walk became a challenge from the programming perspective. An Arduino microcontroller was deployed for this purpose.

“A spider has the ability to modulate the speed at which it extends and contracts its joints to carefully time which limbs are moving forward or backward at any moment,” said Alex Nemiroski, the co-author. “But in our case, the joints’ motion is binary due to the simplicity of our valving system. Either you switch the valve to the pressure source to inflate the balloon in the joint, and thus extend the limb, or you switch the valve to atmosphere to deflate the joint and thus retract the limb. So in the case of the eight-legged robot, we had to develop our own gait compatible with the binary motion of our joints. I’m sure it’s not a brand-new gait, but we could not duplicate precisely how a spider moves for this robot.”

Even though all this sounds like a DIY art-and-craft project, but since the prototype works as a proof of concept, future research can be based on developing such robots using lightweight structural polymers. This might open possibilities of using them in search and rescue operations during natural disasters and in conflict zones.

Watch the robots in action below:


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