PID control loops - closed loop feedback

[Max Lobovsky]

Originally Posted by Larry Barello

For the typical low performance robot (I think FIRST robots count here), PD is needed for position control (proportional/derivative) and PI is needed for velocity control.

Wouldn't it be vice-versa? I thought that the integral is neccesary for reaching the right value.

Originally Posted by Larry Barello

W/velocity control, often folks get away with just the I term. Something like:

output += SomeFudgeFactor * VelocityError;

So if you are slow, the output is built up until you are at the right speed, etc.

how is this the integral? This looks proportional to me, just the current error.