Simulink Control Design™ - MathWorks

Data Types: single | double

start/stop — Start and stop the autotuning experiment

scalar

To start and stop the autotuning process, provide a signal at the start/stop port. When

the value of the signal changes from:

• Negative or zero to positive, the experiment starts


• Positive to negative or zero, the experiment stops

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.

Typically, you can use a signal that changes from 0 to 1 to start the experiment, and from

1 to 0 to stop it. Some points to consider when configuring the start/stop signal include:

• Start the experiment when the plant is at the desired equilibrium operating point. Use
  the initial controller to drive the plant to the operating point. If you have no initial
  controller (open-loop tuning only) you can use a source block connected to u to drive
  the plant to the operating point.


• Avoid any load disturbance to the plant during the experiment. Load disturbance can
  distort the plant output and reduce the accuracy of the frequency-response estimation.


• Let the experiment run long enough for the algorithm to collect sufficient data for a
  good estimate at all frequencies it probes. There are two ways to determine when to
  stop the experiment:
  
  
  • Determine the experiment duration in advance. A conservative estimate for the
    experiment duration is 200/ωc for closed-loop tuning, or 100/ωc for open-loop
    tuning, where ωc is your target bandwidth.
  
  
  • Observe the signal at the % conv output, and stop the experiment when the signal
    stabilizes near 100%.
  
  
  
  


• When you stop the experiment, the block computes tuned PID gains and updates the
  signal at the pid gains port.

You can configure any logic appropriate for your application to control the start and stop

times of the experiment.

Data Types: single | double

16 Blocks — Alphabetical List