This project is a stepper motor that pushes a plunger in a syringe, which drives air into soft gripper.
The equipment used:
Long Machine Screw
Metal Tubing – same width as long machine screw but can fit over it
Short Machine Screw
3D Printing .stl Mold Files
Tools to connect everything:
The arduino receives signals from the IR receiver. Those signals can be used to send different commands to the Easy Driver. The Easy Driver simplifies the process of making the stepper motor rotate.
Power is supplied to the Arduino using a USB cable. The Arduino send power to the Easy Driver, which relays power to the IR receiver and the stepper motor.
A schematic of all the connections is shown below:
You need to solder female header to the Easy Driver & jumper wires to the IR receiver.
Once, you do that, you can connect everything together with jumper wires.
The Arduino Code:
Download the Arduino IDE, which lets us write and load code to the Arduino.
Download the IR signal library, which lets us read IR signals.
If you don’t know how to install a library, view this tutorial.
Create a new window in the Arduino IDE and paste in code from the following file:
Uploading The Code:
Connect the Arduino to your computer with a USB cable.
In the Arduino IDE, do the following:
From the top menu, select Tools → Board → Arduino/Genuino Uno
From the top menu, select Tools → Port → (Serial Port)*
* the Serial Port looks different on each computer. On my Mac, I saw /dev/cu.usbmodemFA131
Press the upload button in the top left. It looks like: →
Testing The Code:
If everything worked, using the IR remote should make the stepper motor rotate now.
These are how the buttons are hooked up:
Power: set full step
C: set half step
B: set quarter step
A:set eighth step
Up: enable the stepper motor
Down: disable the stepper motor
Left: rotate counterclockwise
Right: rotate clockwise
Center: rotate for STEPCOUNT amount of times
Stepper Motor Set Up:
Attach the universal mounting hub to the stepper motor.
Attach three small machine screws to the universal mounting hub.
Take the large machine screw, place the head against the universal mounting hub.
Screw the fourth small machine screw into the universal mounting hub so that it the heads of the four small machine screws hold the large machine screw in place.
You may have to shape the head of the large machine screw so that it fits between the four small machine screw.
It should end up looking like this:
Finally, attach the stepper motor to something stable. I attached mine to some PVC pipe.
Syringe Set Up – Part 1/2:
Remove the plunger from the syringe and cut off the stem of the plunger so you only have the rubber part of the plunger.
I had to use a saw for that. I also used sandpaper to completely remove the stem and leave the plunger smooth.
Take your metal tubing and cut it so that’s a little shorter than the long machine screw.
Now glue and/or tape the coupling nut to the metal tubing, then glue the machine tubing to the bottom of the rubber plunger.
This should have replaced the stem of the plunger with metal tubing and a coupling nut at the end.
Syringe Set Up – Part 2/2:
Now cut some PVC pipe to be the length of the machine screw, then glue and/or tape PVC pipe around the stepper motor.
Now screw the coupling nut all the way down the machine screw.
Finally, glue and/or tape the plastic syringe to the other side of the PVC pipe. The plunger should go into the syringe when you do this.
It end up similar to below.
PneuNets Bending Actuators
3D print the .stl files for the soft mold: 3D Printing .stl Mold Files
The 3D printed files should create 3 pieces. One piece is just a flat base. The other two pieces fit together to make the chambers.
The EcoFlex should come as two containers. Mix the liquid from both containers in a 1:1 ratio. You should not need very much.
Pour the mixed liquid halfway into the flat base mold. Cut out a piece of printer paper to the size of the flat base mold. Place the paper lightly on top of the mixed liquid.
Pour the mixed liquid into the chambers mold. Make sure it goes a little past the top. The chambers should close together on top. They will be open on the bottom.
The paper prevents the base from expanding, so that the chambers expand and cause the mold to bend. When you see the solidified chambers, you should notice a tube like indentation below which will connect air through all the chambers.
You can find out more here: SoftRoboticsToolkit
It takes 4 hours to cure. After that, pour a thin layer of mixed liquid onto the flat base mold. Now remove the solidified chamber rubber and place it on top of the flat base (open part of chambers should on bottom).
Wait another 4 hours, and the mold should be finished. It will be closed all over.
Connect Mold To Syringe
The syringe should come with a thin plastic tube. Take the tube and puncture the side of the mold with it.
Now either glue or add more ecoflex around the tube and the mold to seal them together.
Now do the same to the connection between the syringe and the plastic tube.
The Final Result
Now you can control the stepper motor with the IR remote. The motor should screw the plunger across the syringe, which should inflate or deflate the soft mold.
Replace the IR receiver with an FM receiver. Works better in water & over longer distances.
Use a stronger stepper motor.
Use a different long screw. Machine screws have tight threads, so moving the plunger takes longer. A screw with more separated threads would increase speed.
Use a full soft mold gripper (multiple arms).