Right on Target

A couple of weeks ago, my first year design team competed in the mini design challenge with our beautiful catapult. If you haven’t read my previous post, I suggest you do so now for some more background information on this challenge. Unfortunately, due to miscommunication with the judges, the times that our ping pong ball missed the launch trigger (because of simple bad aim) were counted against us as zero points; however, looking at just the launches where the trigger was successfully set off, we hit the bulls-eye on our target every time, a testament to the engineering behind our catapult design. We decided to go through with the trigger design pictured here, except instead of going under to connect to a release pin, the string that is connected to the lever strapped over the catapult arm, holding a pin over the arm. The design is extremely precise and accurate, and I’m in awe of what our team pulled off. If we had more time, I’m sure we all would’ve agreed to add a tube that the launch ping pong ball could’ve slid down, ensuring that it never missed the trigger.

Next in first year design, we will spend the rest of the semester building an autonomous robot that will be able to navigate up a ramp, navigate past obstacles, release a boom at least 75 cm in height, measure temperature and wind speed, collect ping pong balls, and release ping pong balls based on water conductivity readings. More details on this exciting challenge can be found by clicking on this link here. At the heart of the robot, or as we have named it, our Tubot, will be an Arduino microcontroller. If you have read my ISM blog posts, you know that I am quite familiar with microcontrollers, making this all the more exciting! Stay tuned to witness our progress with our robot! Below are some pictures showcasing our final catapult.

We were given limited materials for this project, so conceptual testing using mock materials was extremely important. Here I try to model our trigger using basic office supplies.

Luke, now an expert with the laser cutter, made our cardboard prototype into a plywood reality.

For stability, the two ends of the catapult are wedged tightly into a base structure.

Here McKenzie and Luke work on a possible laser cut logo for the side of our catapult. Unfortunately, this design aspect did not come to fruition.

Daniel, once again, keeps us all sane with some play-doh entertainment.

Entertainment pt. 2

Entertainment pt. 3

Uh-oh! The dowel rod does not fit through the hole we drilled in the plywood semi circles. Alexander, Natalie, and I took turns trying to sand it down to size.

This is just me trying to be an aesthetic photographer with my foohy monkey eraser in the background of this picture.

Sanding is hard work! Casualties include roughed up fingers and a burning feeling on said fingers.

Does the dowel rod fit now? Unfortunately, no.

Finally, the horizontal dowel rod fits all the way through. To counteract horizontal movement, the rod was trimmed to fit exactly the width of the two semi-circle planks, and the holes were closed off on both the right and left sides.

This was still a rough prototype of the trigger as per the previously drawn design that Shulin (not pictured) was testing. As stated earlier, in the final design, the string strapped over the catapult arm like a seatbelt.

Here, Daniel demonstrates the vertical plank that will serve as an attachment point for the rubber bands that power the catapult.

Luke drilled numerous holes into the side planks of the catapult. By putting a horizontal dowel rod through different holes, a variety of launch angles can be tested.

McKenzie, Alexander, and Natalie work hard to create a cardboard base for the entire structure!

More play-doh breaks definitely took place during this long night. I believe this is Daniel’s interpretation of a hand holding a taco.

This is McKenzie’s master recreation of the famous Daniel play-doh hand.

Popsicle sticks were hot glued down to this corner. This helps hold down the plank with the trigger as it tries to resist against the pull of the catapult arm.

In the Innovation Gym (our engineer workspace here at SMU) “shoes of shame” must be worn if you forget to wear close toed shoes, a concept Natalie is extremely familiar with