It is an old movie trope: a robot grips something and accidentally crushes it with its super robot strength. A little feedback goes a long way, of course, but futuristic robots may also want to employ soft grippers. [Jessica] shows how to build soft grippers made of several cast fingers. The fingers are cast from Ecoflex 00-50, and use air pressure.
A 3D-printed mold is used to cast the Ecoflex fingers, which are only workable for 18 minutes after mixing, so it’s necessary to work fast and have everything ready before you start.
Once cast the Ecoflex is fairly easy to puncture, a paper clip can be enough to punch an air hole through the wall. There may be some leaks that are easier to detect if the part is submerged in water, in which case any holes can be patched with fresh Ecoflex. If an air channel is clogged it may be necessary to recast the whole part, but the mold is reusable.
Speaking of reusing the mold, it’s also possible to create three more fingers and use a 3D printed hub to make an entire gripper hand. As a practical matter, you should probably have force control. Soft grippers can be very — pardon the pun — flexible.
11 thoughts on “[Jessica] Is Soft On Robot Grippers”
“It is an old movie trope: a robot grips something and accidentally crushes it with its super robot strength. ”
Sounds like the beginnings of a horror movie. Or a comedy: “ha ha you crush everything”.
Stretch limiting fabric skins would go a long way to increase durability and maximum working pressures.
I saw a soft gripper made from coffee grounds in a bag some time ago, looked very effective.
In anime and manga there’s an opposing trope; demonstrating the precision of a robot or power armor suit by using it to pick up an egg. You see it a lot in the 80s and 90s, and I feel like it’s a reference to some real world demonstration of an industrial robot or something. 🤔
“A 3D-printed mold is used to cast the Ecoflex fingers, which are only workable for 18 minutes after mixing, so it’s necessary to work fast and have everything ready before you start.”
I think you meant to say the Ecoflex resin has a workability time of 18 minutes so the mold and tools should be set up ahead of preparing the resin. The way this is written makes it seem like the fingers only work for 18 minutes for some reason…
That’s because the average time of someone making these and *not* seeing how much pressure they’ll take is about 17 minutes.
ah, I see.
That means there’s something wrong with me because there’s no way I’d make it 17 minutes before taking it failure. 5 minutes of playing around then blow it up; that’s my moto.
What, no video?
Oh, I just thought the grippers were named Jessica … XD
That’s so cool!
What’s the point of making grippers if they only last 18 minutes? Would the ‘fingers’ be used for lab settings mixing chemical components? I understand there’s a lot of benefits to this, I just can’t conceive anything myself.
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