Ocean NERDs’ Programming and Design Choices

by Coach Charlotte Ackerman

The big challenges for Harrison and the Ocean NERDs were designing for accuracy and programming for consistency. Achieving them required the team to test, analyze, and develop strategies to control building, programming and operator variables. A LEGO robot may look like a toy, but it is actually a complex system. This is an an overview of technical decisions made by the team to minimize variability in robot performance.

A FIRST LEGO League’s (FLL) robot’s capabilities are the end result of a team’s combined skills and decisions. The program shown below tells part of the story: it only works if the robot can drive straight and the operators position it correctly under pressure. Some of the important programming choices the team made were to:

1. Measure distance and turns with rotations. This helped to eliminate the variability caused by changes in battery and power levels.

2. Create a SubVI (this allows you to create your own icon that represents a group of commands) that calculates the number of forward and backward rotations using a constant arrived at in tests of the robot over long distances. This helped reduce the variability on short runs and minimized programming by trial and error.

3. Program the robot from an easy-to-establish starting point on the mat and table. This made it easier for the team to identify the source of problems and make necessary changes to the mission strategy, program or operating routines.

4. Use a subroutine with event programming to stop the robot when the touch sensor was pressed. This is better than trying to measure exactly how far the robot has to go in each situation and allows for a margin of error that is not possible when counting rotations.

5. Insert text labels to annotate each part of the program. This made it easy for team members to share the work of programming and use common elements in more than one program. At the end of the 12 weeks, every team member had worked on and contributed to the robot’s performance at the tournament.

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