12. Soft robotics¶
This week I experimented with soft robotics. Here is each one . Process of thoughts and fabrication.
Thermoadesive vinyl Experiments¶
“Every flower blooms in its own time.”– Ken Petti.
I wanted to create a similar movement to how a flower blooms . Taking advantage of the shape of petals wide at the base and narrow at the end making the movement smoother and more natural.
I started by sketching on paper for which I moved to draw the inner baking paper pattern and cutting it after a somewhat accurate folding. Mind it is all done by hand.
After getting the baking sheet ready, I heat pressed it sandwiched between two thermodasive vinyl sheets.
Heat-press
Put a baking sheet underneath and above the item
Temperature : 130 degrees DUration : 35 seconds
Repeat after flipping on the other side
Note : Make sure the shiny protective layer of the Thermoadesive vinyl is on the outer side.
After taking off the heat press and cooling down in a minute. I started peeling the protective layer carefully and then testing it . It was working well as I blew using a tube pressed by my finger in the middle part.
However, fixing the tube using a heat gun and glue didn't work. I ended up redoing the entire thing but adding a rectangle connected to the middle part for air pumping for which worked much better.
First manual pumping test went like this
Then using a pump and an electric source I got this result.
Silicone Experiments¶
Helix¶
Reading a bit about the movement of soft robotics and how to mold silicone soft robotics I stumbled upon this Research for which I was inspired to experiment how the angle of mold lines can inspire the movement when air pumped.
The basic Idea is that an angled rectangles with a straight connection area may result in a spiral shape (Helix). I wanted to experiment more of how different angles can change the inflated geometry.
I designed 4 molds , in all molds , the rectangles were the same width and height but a different orientation. I opted for 0 , 30, 45, and 60 degrees. The end result was like the following picture. I used autocad for sketching.
Each design consists of 4 parts for one side of the mold and 2 parts for the other side.
The other unpatterned side should preferably be bigger than the main molding side.
To make sure the concept is applicable, I started with one design for which I laser cut on a 3mm Acrylic sheet. Using these setting
Power : 100
Speed : .6
After laser cutting I peeled the protective layer glue using chloroform. Very fast and strong yet not human friendly.
Note : Make sure your mask and gloves are on and try not to breathe the glue.
After 15 minutes the mold is ready and now it is time to protect the casting from sticking to it. I used vaseline , a petroleum jelly that is widely used locally. Brushed the entire thing with vaseline and made sure all corners and edges are well coated.
Now it is time to Prepare the silicone . I used * which is made by scaling the same amount of each part of the **** ' ( Ratio : 1-1 )and then mixing the two together slowly so as to not raise bubbles for 3 min. A total of 200 gram mixture was needed to cover both parts of this mold. I poured the mixture slowly until all was covered. We didn't have a vibrating device to get rid of bubbles so we kept hitting the mold to the surface below to encourage the bubbles to rise. Left the molds for 1 day although based on the package only 4 hours are needed.
After taking the silicone out of the mold carefully. I washed it for 5 min using soap and water and a inal wipe of ethanol to make sure I got rid of vaseline.
Made a new batch of silicone, a small one and glued the two parts together and added a tube for air pumping. Then left for the next day again.
You can download the Autocad file I used to print the mold Here
or you can download the 3 patterns Here
Gripping Angle¶
In this experiment I was looking to see how spaces between the mold horizontal gaps can affect the bending effect.
I used autocad to design for which I exported as .dfx and inserted into rhino to print and laser cut using Trotec.
Just like the previous Experiment, the fabrication is the same. However, In the experiment I didn't make the back mold bigger and I used less than 100 grams of mixture.
After taking it out of the mold and washing it, This is the result.
I redid the experiment as some parts werent glued perfectly.
I tested it after soldering the pump and hooking it to an electric output.
You can download the Autocad file to print the mold Here
You can check this smallresearch about gripping soft robotics that I found helpful.