Note: A high resolution version of the GIF is available in the renders directory.
Many thanks to Marcus Lenander for helping create the design!
The file catapult.mpd contains a 3D model created in LeoCAD. Open it using LeoCAD and use it as a reference when building. One can also open one of either catapult.3ds or catapult.dae as a reference.
After the catapult has been built, 6-8 rubber bands or springs can be added to make the catapult function. A string between the base wheel and the arm also needs to be attached.
An example class built around the catapult can be found in catapult.py. This class assumes that an EV3 brick running the official micropython runtime is used to power the catapult.
from pybricks.parameters import (SoundFile, Color, Port)
from catapult import Catapult
catapult = Catapult(Port.A, Port.B)
catapult.reset()
catapult.safe_lock()
catapult.retract(100)
catapult.unlock()Note that the catapult arm is very strong and may damage itself if used incorrectly. Read through the provided class and always be ready to stop the execution of the program.
Any contribution is welcome. If you're not able to code it yourself, perhaps someone else is - so post an issue if there's anything on your mind.
Although the project is very capable, it is not built with production in mind. Therefore there might be complications when trying to use the catapult for large-scale projects meant for the public. The project was created to easily throw projectiles in a strong and automated way and as such it might not promote best practices nor be performant.