Bumpless Transfer for Open-Loop Tuning
When you use the Open-Loop PID Autotuner, if your controller includes integrator action,
consider implementing signal tracking to avoid integrator windup during the tuning
experiment. Signal tracking enables the PID controller to continue to track the real plant
input while it is out of the loop. Without it, your system can experience a bump when the
control loop is closed at the end of the tuning process.
If your PID controller is a Simulink PID Controller block, you can use the Enable
tracking mode parameter of the controller block to avoid this bump. The following
diagram illustrates a module containing an Open-Loop PID Autotuner block and a PID
Controller block with tracking mode configured. The plant input feeds into the tracking
input of the controller block.
Step 2. Configure Start/Stop Signal
To start and stop the autotuning process, use a signal at the start/stop port. When the
experiment is not running, the block passes signals unchanged from u to u+Δu. In this
state, the block has no impact on plant or controller behavior.
The frequency-response estimation experiment begins and ends with a rising or falling
signal at the start/stop port, respectively. Thus, after deployment, to begin the
autotuning process, use a rising signal at the start/stop port. After an appropriate
time, or after the % conv signal settles near 100, use a falling signal to end the
experiment. When the experiment ends, the algorithm generates the tuned PID gains and
PID Autotuning in Real Time