So we’re done. We competed and did exceptionally. We won, beating second place by more than a factor of two in total points. However, we pulled out of the competition after our last match to ensure that as many high school teams as possible walked away with hardware; despite this we were given a trophy privately later. In short, I think we did alright.

Here’s the final robot specs and a nice little summary of what we could do:

Cool perspective shot!

Cool perspective shot!

First, our drive base. One Vex motor per side, directly driving the tank treads. This was pretty slow on the ground to say the least, but it made the drive very reliable and compact, which was more important for us than overall speed. Our original intention was to use the Motor 393s with their high speed gearing; this would get us a competitive speed without sacrificing the benefits of a direct drive. However, we ordered the wrong motors and got the still-great Motor 269s instead. We ultimately were about as limited by our drive base as our arm speed.

The tank treads were able to climb the stairs once they balanced on the corner of the first step. An idler sprocket was placed about 2 inches from the end sprocket and dropped 1/2″ lower. This made turning easier and helped with high-centering on the electronics board. It also gave us an unintentional “feature”: we could extend our arm to push our CG far enough forward to “rock” onto very short sections of tread, for enhanced turning ability.

The arm had a 25:1 shoulder joint and 7:1 wrist joint, carefully calculated to do all of the work needed. The shoulder joint was powerful enough to lift the entire robot; we used this to get up the stairs by pushing the arm against the second step. This torque was also enough to self right the robot. The wrist joint articulated our claw for grabbing various objects at different angles. Our gripper was a simple Vexplorer claw – it adequately gripped everything, so we moved on to different subsystems. In review, we probably could have done better with a roller claw designed to pick up all of the game objects that happened to have the same width.

All of this together made for a winning robot. For more info on our design process, there are many earlier posts on it; I’ve been meaning to make an “IED category” soon, but never get to it.

Here are our match videos: Match 1 Match 2 Match 3

I’m rather proud of the result as it was quite the excellent robot. I’ve never dominated a competition before, and it’s certainly a pleasant experience.

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