From a software standpoint, if you are deciding to go with a holonomic system (i.e., mecanum or all-omni), your programmers better be ready to learn some physics
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Team 1675 used a mecanum drive for the second time this year, and the programmers have a blast with it. I had so much fun last year just figuring out the way the vectors could change the direction. This year, we worked with the students to develop an algorithm based off an article about all-omni systems in SERVO magazine.
Also, have the programmers work with the drivers to make the controls more comfortable. The programmers can make the controls more or less sensitive (depending on how they are already).