Since I burned a motor right before the competition, I’ve been scrambling to come up with a solution. And I have! The car-style steering system was enough to implement with a single motor, but the tank was more complicated. I ended up coming with a solution inspired by LEGO’s SPIK3R robot, with some significant modifications.

It’s based off the simple principle that, if you can raise one wheel off the ground with a moveable pivot, you can turn on the spot. I used a TowerPro Micro Server SG90 attached to the base using an extranous amount of blue cloth, allowing me to raise one wheel off the ground and acting as a pivot point. Masking tape attached to straight bars acts a balance which prevents the robot from tipping too far in either direction.

A close-up of the pivot attachment (complete with extranous amounts of blue cloth tape) mounted onto the robot.

I kept the same versatile attachment design. This means that I can still attach chunky wheels and rack-and-pinion steering for the Obstacle Course. As I said in the Technical & Artisitic Merit video, it allows for “both high speed and clean manoeuvring in one elegant design.” 😄

The claw, steering, pivot and plain ol' wheel attachments laid out on a white background.

Overall, I think the design encompasses a pretty good set of tradeoffs. The two “modes” clearly represent different challenges — tight manoeuvering and off-road reliability. I have had issues with it getting stuck on bumps in the arena, but I’ve mostly worked those out. In some ways, I feel like burning a motor was a blessing in disguise.