Difference open vs closed loop pid autotuner

I was reading on this the difference:https://in.mathworks.com/help/slcontrol/ug/tune-pid-controller-in-real-time-using-closed-loop-pid-autotuner-block.html

• If you don't have an initial controller, use the Open-Loop PID Autotuner block to obtain one. You can continue using it to re-tune the controller or replace it with the Closed-Loop PID Autotuner.
• If you have an initial controller, use the Closed-Loop PID Autotuner block for re-tuning. The major benefits are: (1) if there is an unexpected disturbance during the experiment, it will be rejected by the existing controller to ensure safe operation; (2) the existing controller will keep the plant running near its nominal operating point by suppressing the perturbation signals as well.

I have to write Autotune code in C lanaguage into a MCU to ttrying to convert code from matlab into C with embedded coder.

What does intial controller mean here?

Answer 1

[Arkadiy Turevskiy]

Hi,

Initial controller means PID controller with the gain values you already have from previois design, educated guesses, etc. As the doc says, if you do not have any guess for PID values, you can use open-loop PID autotuner to obtain them. If you already have a stable controller, but want to improve its' performance, use Closed-Loop PID Autotuner.

HTH