971's Control System

[Bryce Paputa]

Sorry to necro this thread, but I haven't had time to look into this stuff in detail until now and I have a few questions. Looking at the 2013 flywheel controller, the state matrix for the model looks like:

Xdot = [ speeddot ] = [ 0     1          ][ speed ] + [ 0      ] U
       [ inputdot ]   [ 0 -kt/kv/(JG^2R) ][ input ]   [ kt/JGR ]

y = [ 1 0 ][ speed ] = speed
           [ input ]

(that's correct, right?)

The part I don't understand is the -kt/kv/(JG^2R) term. That represents how the wheel slows down over time, right? How is/was it derived?

Another question I have is about arms and gravity, when you're modeling an arm like your claws last year do you just ignore gravity in the model and treat it as a disturbance? It doesn't seem like a linear force to me with how it changes with respect to the arm angle and I can't figure out how to get it into a linear state matrix model.