Final Project Report – Team RAR

Project Summary

Our project is a traditional trebuchet with a modern twist. We added a little bit of technology to this ancient warfare technique. A servo attached to an arduino with a button is used to “pull the pin” and make the trebuchet fire at its target. Our project is based on work with the ardiuno, servo, and button that we have done in the past.

 

Team Members

Rachel S.- Cutting wood pieces for trebuchet, building base, drilling holes for throwing arm, making sling and firing pin

Rachel L.- Building base, and supports for trebuchet, making metal rods to hold throwing arm, blog post and movie, making sling and firing pin

Alex- Programing and building the servo and button to work with the arduino, adding arm to servo

Project Design & Development

We started our project from a existing project design of a trebuchet. We cut all of the wood ourselves and screded it together folling the plans that we found on the internet (link below). We had to modify the release mechanism slightly so that it could be pulled by an arduino. We then programmed an arduino to move a servo when a button was pushed. The servo was attached to the release mechanism, therefore when the button was pushed the servo pulled the pin and the arm was released and basically any relatively light object could be thrown with our trebuchet. We had to test and make sure that the sling would actually release the item that was going to be thrown, and we also had to test and make sure that the servo was able to pull the pin and release the throwing arm.

 http://www.wikihow.com/Build-a-Trebuchet-(1-Meter-Scale)

http://library.thinkquest.org/05aug/00627/chris_and_zach.html

Code from here:  http://forum.arduino.cc/index.php?topic=108375.0

 

Project Challenges & Insights

The first problem we encountered was fairly easy to fix, we had decided to use a very hard wood (oak) for the base. We could screw the screws directly into so we had to drill a pilot hole and then attach the pieces of the base and supports with the screws. The other problem we encountered was how to make the release mechanism for the throwing arm automatic. We knew that we wanted to use the servo to make it fire but we had to figure out something that would be light enough for the servo to pull. We ended up using a chain with a small pin that when pulled out released the arm, kind of like a grenade. The biggest problem was getting the ball to come out of the sling properly. We tried making the sling out of cloth, rubber bands and tape, and cardboard. Either the ball came out before the arm go to the top of its swing, throwing the ball backwards, or else is didn’t come out of the sling at all. We actually were not able to fix this problem, so our trebuchet was not fully functional. 

Project Video

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