By the end of the morning, we had more than ten viable competitors with a variety of programs and body designs. A major challenge in construction is keeping the robot within the 9 square inch size limit. Many of the robots needed to be modified in order to fit. Another limitation for the robots is that they must weigh less than 32 ounces. Interestingly, most of the builders were finding it difficult to get their robots above 24 ounces. As is the case with Sumo wrestlers, heavier competitors push harder, and are harder to push around.
The student team above experimented with gearing down their motors -- putting small gears on the motor axles to turn larger gears on the wheel axles. They ended up with a 2:1 ratio which made the robot slower than others, but far more powerful.
We also had the chance to focus for longer periods of time on programming. The sumo robots need to do three things autonomously:
- locate their opponent
- push their opponent out of the ring
- retreat from the white edge of the sumo ring
These creations are not remote controlled. On the contrary, the builders press a button on the EV3 brick, and step back. The robots have to think on their own using the programs the students wrote for them. The more I tinker with the LEGO Mindstorms programming environment, the more nuanced my understanding of it becomes. The best programs for this purpose seemed to be the ones with two loops nested in one big loop. We also learned about the different ways to stop a loop from running.
A powerful aspect of the Mindstorms kits is that you can run programs while the robot is connected to the computer, and the blocks of the program become animated while they are running. This allows the programmer to see what's working and what's not working in real time.
Of course, there were many practice bouts on the official Sumo ring which was set up in the library. By all indications, the main event on Monday, December 21st in The Pit at Morse High School from 6:30 until 8:00 is going to be GREAT. We will have a tournament bracket projected on the wall, and robots will face off in a round of double elimination. By the end of the night we will have a first, second and third place finisher, and as of now, I have no idea which teams will prevail. If you're interested and available, you ought to come out next Monday to check out the action! It's a lot of fun!