Beater Bar Launch MechanismTags: mechanical and video
Task: Design deployment mechanism for beater bar
Similarly to last year, the beater bar on our robot needs to be deployed in order to stay within the size limit. Using motors would make the robot heavier, and potentially too heavy to go up the ramp anymore. Bungee cords are something that we've always resorted to in order to save weight, so we decided to use them once again. By tying them to the back of the beater bar sliders and wrapping them around the robot to create more tension, we managed to make a crossbow-like mechanism that launches the beater bar forward. Small stand-offs were also used to make sure the beater bar doesn't rotate backwards.
As you can see from the video, the launcher actually works pretty well. There are a couple of problems with it though. Firstly, the force required to pull the beater bar back to the correct position is is very large, and might not be practical. Secondly, the knots we made, although certified by Boy Scout knot-master Evan, might undo themselves during competition. Thirdly, the beater bar might break due to it repeatedly smacking on the end of the track. Although we're probably going to redo the entire thing eventually, it's a good start towards making similar mechanisms, such as our idea for how we're going to hang on the cliff. We may decide on a design where the launch is done by motors rather than potential energy, but that will be a decision to make later.