I have a few questions in terms of closed-loop control, specifically for an arm which rotates 180 degrees.
Using the TalonSRX + the SRX magnetic encoder, which application would work best in terms of inputting a setpoint angle and having the arm move to said angle: Motion Magic, Motion Profiling, or Position Closed Loop?
I understand how PID works, but I am confused when it comes to PIDf. I read nickbrickmaster’s post (Velocity Limiting PID) on determining the feedforward value through physics, but am confused on how you would apply it in the case of using closed-loop control with the TalonSRX’s and setting the gains. Assuming that the voltage necessary to hold the arm is FF = (Arm Weight) * (Distance to arm center of mass) / (Motor stall torque) * (Number of motors) * (Gear Ratio) ] * cos(theta) (taken from nick’s post), this implies that the feedforward value changes as the arm moves.
In order to use this, wouldn’t you have to change the kF gain as the arm moves? Am I missing something?