Merav Gazit


Week 14_Final Project


Project 14g
An Inflatable surface, made from Soft Pneumatic Actuators.
Project 14g2
Project 15a
The technique is similar to the one being used in the Harvard soft robot project (Molding and casting of rubber). In order to learn more about the technique, I also found these 2 tutorials very useful:1 , 2
Project 14h
The surface will be controlled by hand gestures or by the touch_pad I made for input_devices week
Project 14i
Electronics Scheme
Project 14k
Project 14l
Building the mold in grasshopper. The sliders allow to modify the air chambers properties.
Project 15b
3d printing the mold
Project 15b2
Preparing all the materials for casting the Ecoflex. Ecoflex 00-30 for the top mold and ecoflex 00-50 for the bottom mold.
Project 15b3
Casting silicon _ de-gassing_ curing in the oven for 10 minutes at 150F (Instead of 4 hours cure time for Ecoflex 00-30 and 3 hours cure time for Ecoflex 00-50). Ecoflex 00-30 pot life is 45 minutes, so you can take it easy...

Project 15b4

Removing the silicone from the mold. I used a lot of mold release before casting, otherwise the small chambers get stuck in the mold.

Project 15b5

Top part of the surface.

Project 15b6

Top and bottom parts of the surface being glued together (after curing) with another layer of Ecoflex.

Project 15b9

The surface in action!
Project 15b10



Project 15b11



Project 15b12

Project 15b13
While preparing and testing the silicon surface, I started working on the schematic in eagle. A MOSFET circuit that will be attached to the 4 solenoid valves. The plan was to power the microcontroller (at the fabduino board) through the computer, and to power the MOSFETS through a 12V power supply, using common ground. I added a big capacitor (100uf) across the mosfets power supply.

Project 15b14

Tracing the board. In order to determine the traces thickness, I used the above calculator (sent by Jeff). Surprisingly I didn’t need to use thicker traces then the one we usually use. I made them a little bit thicker the usual, just in case.

Project 15b15
Trying to program the board + fabduino with the fabISP on Arduino (The green wire between the MOSFETS circuit and the fabduino is for common ground). I straggled a lot with that part... I kept getting error massages... The last one was that the programmer is not responding. I double checked the fabISP with other boards and it worked perfectly. I believe that there was some kind of problem with the fabduino.
Project 15b16
Preparing all the connection for the Solenoids (air and power).Because of size differences between the solenoids and the tubes I ordered, I hacked some DIY fittings using Black mastic sealing tape and stretchy silicone tubes.
Project 15b17
On my final attempt to program the board, I used an arduino board with my MOSFETS circuit. I was able to program, but right now the solenoids are only able to stay open, and they all open at ones, so I'm unable to control them separately and create a more active movement in the surface. I really hope to be able to solve these issues soon...
Project 15b18
Inflating the surface with an air compressor while powering the mosfet circuit (during class presentation) .In order to solve the above-mentioned issues with the solenoids, Nadya (the TA) offered that I might need to add diodes to the circuit , and that I should try to use a higher power supply (even though the solenoids should take only 12V and 320mA each). Hope to update with a successful solution soon!
Video of the surface when the 4 chambers inflate at the same time. Once I'll be able control each chamber separately, the surface will be able to achieve much greater motion..
Partial list of materials + costs: Ecoflex 00-30 Trial Kit : 30$. Ecoflex 00-50 Trial Kit : 30$. Solenoid Valves X 4 : 6.95$ each. Air compressor - borrowed air brush compressor (should cost about 70$, but I could have definitely used less powerful air compressor, and therefore, cheaper). Silicon Squeeze Bulb for experiments X 2 : 5$ each. High-Temperature Silicone Rubber Tubing Soft, 1/8" ID, 1/4" OD, 10 ft. Length : 6.9$. Crack-Resistant Polyethylene Tubing 1/16" ID, 1/8" OD, 25 ft. Length: 1.25$. Black Mastic Sealing Tape.  
Finally, I would like to thank the TA's - Jean-Francois Duval, David Costanza and especially Diego Pinochet for all the help and advices.