FLL: The Debriefing

So it looks like another great FLL season has come and gone... but a very different one this time, in that for the first time it involved two very different platforms, the RCX and the NXT. So, before all you teams disband for the season and scatter to the four winds, how about collecting some thoughts on the season? I'm really interested in several things:

1) How did having two very different robot platforms in the event change things?

2) What special tips or tricks could you pass on for working with the NXT, NXT-G, and the newer version of Robolab?

3) Words of wisdom (or howls of complaint) to pass on to folks for nxt year, dealing with the hardware, software, or the way the contest was organized/run?

Please take a moment to pass on what you've learned (if that isn't a good goal for FLL, what is?) Just add any FLL team or coach comments into the comments section of this post - I'd love to read them! And maybe others will as well. Thanks!

Brian Davis


Anonymous said…
My team learned that even though odometry is better with the NXT it is still a poor way to navigate. Many teams had problems going from the practice tables to the competition table. Don't forget all the tricks you learned using the RCX.

Rear wheel drive robots that wobble side to side driving forward will often go straighter in reverse. When driving forward the drag of the non-powered balance wheels introduces a disturbance to the PID loop that controls the motors. When driving backwards the drag acts like a damper. Think about putting your drive wheels in the front of the robot.

NXT-G is easier to work with and more robust (at least the GUI) when you make extensive use of MyBlocks. We had problem with the program crashing on our super fast XP laptop if the number of blocks and data wires became large (> 20).

Don't support your wheels only using the motors. Provide additional support to keep the wheels aligned and prevent them from sagging. Adding only 8 parts to my team's FLL robot greatly improved its accuracy.

The move block is extremely complicated. Read the help about the Move block and the Reset block to understand its behavior. Pay special attention to the next action being Move or Coast. These have a greater effect than just how fast the robot stops.

Requests to LEGO/NI
Please make the NXT firmware run faster. My RCX should not be able to line follow 4 times as fast as an NXT.

Please make NXT programs compile to a smaller file. The NXT would have plenty of memory if the programs weren't so big. ROBOLAB teams stared blankly at me when I asked if they ran into any memory limitations.

Please may auto layout of blocks and data wires optional. I dread changing an NXT program that has more than a few blocks and data wires.

Add a remove broken wires feature. I know it is available, but it should be in the standard software.

Make the blocks a little smaller.

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