Simulink Control Design™ - MathWorks

Positive. Otherwise, specify negative. For stable plants, the sign of the plant is the sign

of the plant DC gain.

Programmatic Use

Block Parameter: PlantSign

Type: character vector

Values: 'Positive' | 'Negative'

Default: 'Positive'

Sine Amplitudes — Amplitude of sinusoidal perturbations

1 (default) | scalar | vector of length 5

During the experiment, the block injects a sinusoidal signal into the plant at the

frequencies [1/10, 1/3, 1, 3, 10]ωc , where ωc is the target bandwidth for tuning. Use Sine

Amplitudes to specify the amplitude of each of these injected signals. Specify a:

• Scalar value to inject the same amplitude at each frequency


• Vector of length 5 to specify a different amplitude at each of [1/10, 1/3, 1, 3, 10]ωc

In a typical plant with typical target bandwidth, the magnitudes of the plant responses at

the experiment frequencies do not vary widely. In such cases, you can use a scalar value

to apply the same magnitude perturbation at all frequencies. However, if you know that

the response decays sharply over the frequency range, consider decreasing the amplitude

of the lower-frequency inputs and increasing the amplitude of the higher-frequency

inputs. It is numerically better for the estimation experiment when all the plant responses

have comparable magnitudes.

The perturbation amplitudes must be:

• Large enough that the perturbation overcomes any deadband in the plant actuator and
  generates a response above the noise level


• Small enough to keep the plant running within the approximately linear region near
  the nominal operating point, and to avoid saturating the plant input or output

In the experiment, the sinusoidal signals are superimposed. Thus, the perturbation can be

at least as large as the sum of all amplitudes. Make sure that the largest possible

perturbation is within the range of your plant actuator. Saturating the actuator can

introduce errors into the estimated frequency response.

To provide the sine amplitudes via an input port, select Use external source.

Tunable: Yes

16 Blocks — Alphabetical List