Trouble in squishy hand experiment

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sidharth
Posts: 3
Joined: Wed Nov 26, 2014 5:30 pm
Occupation: Student: 9th Grade
Project Question: I am working on squishy robot: http://www.sciencebuddies.org/science-f ... html.Built a large squishy hand using ecoflex 30 & 50. When I inflate, the fingers of robot don’t curl enough and is unable to grip any object.
Project Due Date: The date my project is due is 1/5/2015
Project Status: I am conducting my experiment

Trouble in squishy hand experiment

Post by sidharth »

Hi,
I am working on the Squishy Robot project: https://www.sciencebuddies.org/science- ... p020.shtml

I have built a large squishy hand using ecoflex 30 & 50. When I inflate, the fingers of the robot don’t curl enough and is unable to grip any object. To fix this I put another layer of ecoflex 50 to the bottom of the robot. Is there any other way to fix this issue? Also, I have made many robots, but each one has some or the other issue, like only one finger inflating etc. Is there any place where I can get this robot built properly?

Thanks a lot for your timely help and advice,
Sidharth
bfinio
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Re: Trouble in squishy hand experiment

Post by bfinio »

Hi Sidharth,

This is a tough project to get working perfectly, and it takes some practice The performance of a robot can be VERY sensitive to a couple things that you need to be careful about:

- Using too much or too little "glue layer". If you use too much glue and clog one of the channels, that can prevent a leg from inflating. Hold your robot up to a bright light and you should be able to see if any of the interior channels are clogged. Unfortunately there's no real way to fix that.
- Make sure you let the Ecoflex cure while the mold is sitting on a perfectly flat surface. Use a level to check if the surface is flat (in both directions, forward-backward and left-right) if necessary. If the mold is tilted even a little bit to one side, that will cause more of the Ecoflex to flow toward one side of the mold. Then, one leg will be thicker than the others, and one will be thinner - the thinner leg will be the weakest, so it will inflate first.

If it isn't too late, you might want to try using the smaller molds instead, since they use less ecoflex per robot and should allow you to make more. Overall, I encourage you not to get frustrated and keep trying - this process was developed by Ph.D. scientists in a lab at Harvard, so it's impressive that you can get it working at all at home!

-Ben
sidharth
Posts: 3
Joined: Wed Nov 26, 2014 5:30 pm
Occupation: Student: 9th Grade
Project Question: I am working on squishy robot: http://www.sciencebuddies.org/science-f ... html.Built a large squishy hand using ecoflex 30 & 50. When I inflate, the fingers of robot don’t curl enough and is unable to grip any object.
Project Due Date: The date my project is due is 1/5/2015
Project Status: I am conducting my experiment

Re: Trouble in squishy hand experiment

Post by sidharth »

Hi Ben,

Thank you for your help. As you had mentioned I constructed a wooden leveled surface. I placed the molds on them and spread the glue layer evenly and constructed two more squishy hands .But still one leg inflates more than the others, and I am not able to figure out why this is happening. Do you have any more pointers to solve this issue?. Also, Is it possible for me to request a lab to make this squishy hand for me?

Thank you so much for all your help,
Sidharth
sidharth
Posts: 3
Joined: Wed Nov 26, 2014 5:30 pm
Occupation: Student: 9th Grade
Project Question: I am working on squishy robot: http://www.sciencebuddies.org/science-f ... html.Built a large squishy hand using ecoflex 30 & 50. When I inflate, the fingers of robot don’t curl enough and is unable to grip any object.
Project Due Date: The date my project is due is 1/5/2015
Project Status: I am conducting my experiment

Re: Trouble in squishy hand experiment

Post by sidharth »

Hi Ben,

In the squishy hand project, I must pump the squeeze bulb to inflate the hand, which does not allow me to deflate the hand without disconnecting the pump itself. Is it possible that I can attach a pneumatic pump that is capable of pumping air into the hand, being able to hold at a certain pressure, and is able to release the pressure to deflate the hand? If so, what kind of pneumatic pump can I use?

Thank you so much for all your help,
Sidharth
bfinio
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Posts: 748
Joined: Mon Aug 12, 2013 2:41 pm
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Re: Trouble in squishy hand experiment

Post by bfinio »

Hi Sidharth,

Two answers:

1. Unfortunately there is really not more I can do to help you troubleshoot over the internet. I have done after-school programs and summer camps where dozens of kids build these robots, and typically there is about a 50-75% success rate depending on how careful the kids are. Even I would make "bad" robots sometimes, so it is very difficult to get a 100% success rate. Did you actually use a level to make sure the wooden surface is perfectly level? Just because it looks flat doesn't mean it isn't tilted a little bit.

2. These robots were invented at Harvard University in Cambridge, Massachusetts. If you happen to live near Boston you might be able to try and contact them, but I wouldn't get your hopes up (they probably get so many emails that they can't respond to them all): http://gmwgroup.harvard.edu/

3. Usually there is a small leak around the air tube, which causes the robot to slowly deflate after you inflate it with the bulb. If you have a perfect seal then you are correct, there's no way to deflate the robot without disconnecting the pump. You MIGHT be able to use an aquarium pump, like this, but I cannot guarantee that it will work: http://www.amazon.com/Tetra-77851-Whisp ... B0009YJ4N6
frginc
Posts: 1
Joined: Thu Feb 11, 2016 7:45 am
Occupation: Parent

Re: Trouble in squishy hand experiment

Post by frginc »

Where do we get the file for the mold? It won't download, do we need to purchase it?

Thanks,

Yanina Szenkman
bfinio
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Joined: Mon Aug 12, 2013 2:41 pm
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Re: Trouble in squishy hand experiment

Post by bfinio »

Hi Yanina - are you trying the download links on this page?

https://www.sciencebuddies.org/science- ... #materials

I just tried and they worked for me. Maybe the problem is with browser security settings or a firewall that is preventing your download?
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