One speed vs Two speed gearboxes

[asid61]

Originally Posted by Jared

It really depends on your strategy. That said, a reliable shifting gearbox will never hurt.

If you look at some very successful teams, you'll see that some teams like 254 have run two speed transmissions for over 10 years. On the other hand, team 118 didn't have a two speed gearbox in 2011, 2012, 2013, or 2014, and they were very successful. 118 has also put brakes on their gearbox in the recent past too.




I've seen you say this a few times. How would you set up an auto-shift system? When do you shift up and shift down?

Autoshifting is done by either current sensing or heat sensing on the main breaker. When the current spikes (or the heat) for an extended period of time, you shift down. You can find a curve fit for the graph of the main breaker current limit versus time, or just have hard limits and times. This prevents breaker blows.
Generally you only need to utilize this in a pushing match, and the driver gets distracted. You could potentially also use collision detection, where the driver is pushing on the joystick but the robot is not moving. Then the program shifts down after a couple seconds. Shifting up is manual.
There is a number of ways to accomplish autoshifting.