As many of the experienced teams have mentioned, the robot not going straight is a common problem. Weight distribution on the robot can sometimes be an obvious cause. The tire tread coming of the wheel sometimes can be the cause. Even with better weight distribution and extensive motor matching, teams may still find that their robot is not perfectly straight.
In general, teams should try to use multiple techniques to straighten out their robot. In our Intermediate Reliability Lesson on EV3Lessons.com, we talk about finding lines, straightening out on lines, bumping into mission models, bumping into walls, etc. Using multiple techniques and repeating them can help your robot "go straight" more often.
In Advanced, we do have a Gyro Move Straight and Wall Follow Lesson for teams interested in learning how to use the Gyro to move straight.
As an aside, the FLL team behind EV3Lessons.com will be in the Reston area on Nov. 20-21. If teams have an interest in getting together, let us know and we can figure something out.
-- To UNSUBSCRIBE or CHANGE your settings, please visit https://listserv.jmu.edu/archives/vadcfll-l.html and select "Join or leave the list".
-- VADCFLL administrative announcements are sent via VADCFLL-ANNOUNCEMENTS-L. Visit https://listserv.jmu.edu/archives/vadcfll-ANNOUNCEMENTS-l.html to subscribe.