PID Inputs and Outputs

[Triapod]

I am wondering if the inputs into the PID SubVI need to be scaled in order to match the input.

I meant output there

I did make the setpoint and the process variable the same scale by having the second Encoder Get wired to the shift register, but the main concern is whether it is a problem having the PID control a speed based on an error in angle.

My process value and outputs are angle so they can by as high as 90 degrees or more. Its the output range that I've limited to -1 to 1 in order to match motor speed.

[Vikesrock]

Not a problem at all. As you've observed it will simply effect the magnitude of the gains.

[Triapod]

Thank you for the responses. The method works -- just needed to be careful of the integral gain that caused a periodic motion.

[jhersh]

I recommend removing the error wire between the Motor SetOutput and the Encoder Get. This will allow those two independent operations to run in parallel.

-Joe

[Triapod]

Originally Posted by jhersh

I recommend removing the error wire between the Motor SetOutput and the Encoder Get. This will allow those two independent operations to run in parallel.

-Joe

I thought to get the new encoder value right after the motor input has been sent from the PID in each iteration. I'll see if it makes a difference

Also in the image, the encoder should be started