Quick question about the magnets. I'm a 2nd year coach but this is the first I've heard of them. I see how and what to order, but exactly how did your team use them? Are they used to attach attachments to the robot instead of "clicking" Legos together? Did you ever have problems with attachments falling off their magnets, or are they pretty strong?
Answer
Magnets: Don't over-rate their usefulness. They are 1 means to an end. There are multiple ways to do what we are doing with magnets. The logic-stream goes like this.
1 - Highly specialized tools are more effective at performing specific tasks with simple programming.
2 - Time is the most limiting resource in an FLL round.
3 - If we can make attachment switching both very fast and reliable then we can utilize highly specialized tools without running out of time.
4 - We used magnets. We have seen other teams use a girder in hole kind of method, one team had a standard slot under the robot and pushed tools out and left them on the field, and one other team used a remove tools only kind of process. The goal is the same. To make the in base transitions quick, reliable, and easy for the kids to do.
This year we had 3 different tools that attached in the same way to the front of the robot, with magnets, and 1 more tool that snapped over the arm and attached with magnets. This year our robot had a flat front made out of girders. That flat front had 2 one pip spots in it where the girders left a hole. The tools had flat backs (to mesh with the robots flat front) except where the robot had a hole, the tools had a girder sticking out 1 pip (we used an "L" girder to accomplish it), that would fit in the hole in the front of the robot. So the tool, if held against the front of the robot, was generally stable and would not slide around if held against the front of the robot. The magnets were then used to "hold" the tool against the front of the robot. The magnets weren't needed to keep the tool from getting too close to the robot. The magnets weren't needed to keep the tool from sliding around on the front of the robot. The magnets were only needed to keep the tool from pulling away from the front of the robot.
We've designed a Cougar Workshop Bot. And the Incredibots have designed an EV3 version. It's a simple robot designed just for the workshop. So If you don't already have a robot for the workshop try this one. You should be able to build it in about 1/2 an hour. It's the simplest robot we could come up with that could do ALL of the labs. It's only got 79 parts plus 6 wires. With 2 light and 2 touch sensors appropriately located you can try out the back-to-wall and advance-to-line programs.
This is our Cougar Advance To Line program. It is used to line up perpendicular to a line. We used it a lot last year to re-align mid run out on the field.
This program is based on our 2008 robot, "CA White". Motor C is on the left side of the robot. Motor B is on the right side of the robot. Light sensor 1 is on the left side of the robot. Light sensor 4 is on the right side of the robot.
It will, in two threads:
Run motor C at 90% power, 2 degrees per loop, checking light sensor 1 to see if the light level has gone below 50
Run motor B at 90% power, 2 degrees per loop, checking light sensor 4 to see if the light level has gone below 50.
Each motor will stop when the light sensor associated with them drops below 50, causing the robot to align perpendicular to a line
Our Mission Select program. This program detects which button is pressed and sets a corresponding variable (LB, EB, or RB) to true based on that choice. If EB or RB are chosen it also sets the variable "Exit Loop" to true. These values control the execution path of our master program.
