[Ken Streeter]

Originally Posted by JamesCH95

Have you found a story of any team that switched to two-stick tank from any other method of control? I can only find threads like this, where teams ditched two-stick tank for another method they found to be superior.

Over the past few years, we've used both two-stick tank drive and the FPS-style drive (although we call our version "Speed Racer Drive" even though it isn't actually the drive we used for Speed Racer in 2008 - for Speed Racer we actually used a Steering wheel and foot pedal).

However, there is one maneuver that the two-stick tank drive makes easy that I haven't found a good way to replicate on the FPS drive -- the "pivot turn."

For two-stick "tank drive" on a skid steer, the "pivot turn" is easy to execute -- to pivot about the left side of the robot, move just the right stick; to pivot about the right side of the robot, move just the left stick. We haven't found a good way to get this motion using an FPS, as such a motion requires a coordinated synchronization of the forward/back stick and the rotation stick.

Any teams have some good suggestions on how to do "pivot turns" with an FPS control approach?

Essentially, this is the complementary problem to that of a two-stick tank drive having trouble making arcing turns (or, to a lesser extent, driving straight at low power settings).

Back when we used two-stick tank controls for a skid-steer robot, we solved the "drive straight" problem by having a "trigger" on one of the sticks be a "drive straight override" -- in that case, only the stick with the trigger held is used to determine robot speed, and both sides of the robot were given the same motor commands to "drive straight."

In any case, why do I ask about doing "pivot turns" with an FPS control approach? Well, we used "Speed Racer Drive" (FPS) on our robot last year, but have found that the "pivot turn" maneuver is often helpful for lining up on totes. Getting the robot to gently do a "pivot turn" is very hard for FPS, but would be pretty easy for a two-stick tank. (So, yes, we're considering switching back for this year, due to the usefulness of the "pivot turn" when aligning against a tote.)