[Merfoo]

Originally Posted by Jared

Our PID controller is here: https://github.com/dicarlo236/2015-R...robot/PID.java
Our Updater that deals with PID is here: https://github.com/dicarlo236/2015-R...t/Updater.java

I assumed that I messed up something in my PID class for the derivative calculation, so I took it out, and we're only running P control now.

I believe the mistake you made for the derivative calculation is that you never update the variable lastError in your update function. You also don't appear to initialize the variables i and lastError so if you try to run this code you'll get variable uninitialized errors, but I think you fixed this at competition and just didn't push that code to github else I don't see how this could work.

@Override
	public void update() {
		// PID calculations
		double dt = .02; // length of time between each calculation
		// calculate how far from our target we are
		double error = setPoint - source.pidGet();
		// p is proportional to error and our kP gain
		double p = error;
		// integrate error
		i += error * dt;
		// make sure it isn't too big
		coerce(i, -max_I, max_I);
		// differentiate error
		double dError_dt = (error - lastError) / dt;
		double d = dError_dt;
		//output is sum of all terms multiplied by gains
		double result = kP * p + kI * i + kD * d;

		// check to see if we're at our target
		if ((Math.abs(dError_dt) < max_derror_dt)
				&& (Math.abs(error) < max_error)) {
			// reset I if we want to
			//possibly add decay?
			i = (reset_I_whenOnTarget) ? 0 : i;
		}
		
		//set output
		if(enabled){
			output.pidWrite(result);
		}
		
		
		
	}