Sharon Youth Robotics Association

"FLL Secrets"

"FLL Secrets" of the Sharon Mentors team

Dead reckoning on a straight line can accomplish many missions.  How many of this seasons missions can be approached in a straight line?

Actually going straight isn't always easy . . .

Some wheels turn more or less easily.

If the right and left wheel(s) are bound together by an axle, they will resist turning. These wheels could be modular (snap on, snap off).

If you need to turn and go straight as well . . .

Following a wall can help, too, along with wheels that run on the side of the wall itself.

Matching motors that turn at about the same speed can help.

Turning, backing into a wall, and then proceeding forward to square off can help.

Using the Eagle OverDrive design can help.

Distance is important . . .

Time-based distances vary with battery strength.

Use a rotation sensor for reliable distances (remember, 16 to the full turn).

In rotation sensor code, always test for >, not = (if it misses the count, it goes forever).

Rotation sensor is most reliable when it turns at about 300 rpm (motor speed).

Rotation counts can be used for turning, as well.

Aiming can be a challenge . . .

Jigs can be used in base to aim (only made of LEGO parts).

Start against wall, to reduce positioning errors.

Build sighting pieces on top of robot, for operator to aim.

Modular robot design can help . . .

Snap on, snap off modules for different missions.

Build securely, vertical bracing pieces are important (your robot is always most likely to break when you are most excited, and that would be when you are competing).

Core robot can have all three allowed motors. Use two for differential left/right drive, one for powered attachments, like the power takeoff on a tractor.

One way to have more than 5 programs on an RCX - choose to execute one stack of code or another based on a switch being open or closed.  A jumper with the ends connected together, placed on a sensor input, will substitute for a closed switch.  No jumper shows an an open switch.

Use LEGO pieces on your motor and sensor cables to color code which cable connects where.  LEGO pieces with numbers, letters or pictures can also show which direction they show point.

Slower robots can be more precise, but time is valuable.

Try to combine missions that are at the far end of the table ("car pooling" for the long trip).

At the tournament . . .

Mission order is important. Consider your most reliable missions - never let yourself run out of time to perform them.  Consider the possibility of reversing scores that you already achieved.

One team member should follow the robot down the field to bring back quickly if it gets lost. Three points is much cheaper than the lost time, and possible field damage that could affect your score.

Bring a cart/table/box to hold the various parts of your robot next to the competition table.

Bring an opaque box, to put the IR tower and the RCX/robot in if program loading is needed.

Bring an extra RCX module, pre-loaded with your programs, to help with battery changes and as a backup if a problem arises with the first RCX.

If your RCX has an AC adapter jack, use an AC adapter when changing batteries, to avoid firmware and program re-loading.

Bring a laptop w/programming software loaded, IR tower, and your robot programs.

If you get into trouble, ask for help!  Gracious professionalism means that all sorts of experienced team members will be glad to help you out!

Bring a reference sheet, to remind you of mission/program/module order during competition.

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Last modified: 11/04/11     All Rights Reserved, © 2011 by Team Unlimited [FTC 0001]