Lego Racer

Your task: create a Lego vehicle with a single motor, powered by a PicoCricket, that can carry a 1.0 kg weight as fast as possible on a 4 meter course.
On your mark, get set, GO!

One of our earlier designs with really high torque

We started with an introduction with gears and gear ratios, our main takeaway was that torque and speed are inversely proportional. Using this knowledge and the knowledge that the motors we used were high speed, we set out to first up the speed enough to carry the 1 kg weight.
This quickly proved not as easy as we thought it would be because we had to also come up with the most strategic way to also store the weight, PicoCricket, and also correctly position the motor so the gears line up. We tried really bulky designs specifically targeting holding the many parts but reasoned that there were more efficient ways to make a car and scrapped it. We also finagled with the gear and motor connection and figured that a 2 wheel drive was all that was necessary for this race.

Our first running car had a gear ratio of 1:525 because we had 4 pairs of 8:40 tooth gears and featured an inversed Lego design, meaning all the pegs for the Legos were facing down because we figured that we can more easily put the motor and the motor board on the car.

With our first working car being very slow we decided to test out other gear ratios:

1. higher speed/lower torque: 8:24+ 8:24 Gear Ratio: 1:9 Result: too weak to carry weight
2. since torque was too low lets add more gears:  8:24+8:24+8:40 GR: 1:45 Result: completes 4 m in 16 sec
3. Still a little slow, lets reduce torque: 8:24+8:24 8:24 GR: 1:27 Result: completes 4 m in 11 sec
4. let's see if we can make it faster! 8:24+8:40 GR: 1:15 Result: completes 4 m in 8 sec! Yay!

Final Design

 Our final design was very minimalist to increase the speed as much as possible. We supported the PicoCricket and the weight between between two little walls of Legos. We also found out that making the big wheels the driven wheel is an advantage because they have more distance per roll due to their large circumference.

Our final race finished in ~8 seconds despite having slight complications with the PicoCricket not cooperating for a little bit. It was interesting to look at the results because 2 other teams also had the same gear ratio but were up to 4 seconds slower, after some caparison we realized that this was because despite having the same gear ratio the other teams used more gears than we did which added friction. If we were to improve our design we would try to make the walls supporting the weight and the PicoCricket more durable because we often knocked the walls over when taking the weights on and off the car. This was a takeaway of inversing all the Legos, so to solvethis we could use thicker blocks for walls.