BodePlot - Plot Bode frequency response of dynamic system (2024)

Dynamic system, specified as a SISO or MIMO dynamic system model or array of dynamic system models. Dynamic systems that you can use include:

If sys is an array of models, the plot shows responses of all models in the array on the same axes.

Line style, marker, and color, specified as a string or character vector containing symbols. The symbols can appear in any order. You do not need to specify all three characteristics (line style, marker, and color). For example, if you omit the line style and specify the marker, then the plot shows only the marker and no line.

Example: '--or' is a red dashed line with circle markers

Frequencies at which to compute the response, specified as one of the following:

For models with complex coefficients, if you specify a frequency range of [w_min,w_max] for your plot, then in:

Specify frequencies in units of rad/TimeUnit, where TimeUnit is the TimeUnit property of the model.

Parent container of the chart, specified as one of the following objects:

• "Hz"

• "rad/s"

• "rpm"

• "kHz"

• "MHz"

• "GHz"

• "rad/nanosecond"

• "rad/microsecond"

• "rad/millisecond"

• "rad/minute"

• "rad/hour"

• "rad/day"

• "rad/week"

• "rad/month"

• "rad/year"

• "cycles/nanosecond"

• "cycles/microsecond"

• "cycles/millisecond"

• "cycles/hour"

• "cycles/day"

• "cycles/week"

• "cycles/month"

• "cycles/year"

• "dB" — Decibels

• "abs" — Absolute value

• If MagnitudeScale is "log" when you set MagnitudeUnit to "dB", the software automatically changes MagnitudeScale to "linear".

• The default magnitude units depend on the toolbox preferences. For more information, see Specify Toolbox Preferences for Linear Analysis Plots.

• Setting MagnitudeScale to "log" is not supported when MagnitudeUnit is "dB".

• The default magnitude scale depends on the toolbox preferences. For more information, see Specify Toolbox Preferences for Linear Analysis Plots.

• "deg" — Degrees

• "rad" — Radians

• "on", 1, or true — Display the magnitude plot.

• "off", 0, or false — Hide the magnitude plot.

• "on", 1, or true — Display the phase plot.

• "off", 0, or false — Hide the phase plot.

• "on", 1, or true — Enable phase wrapping. The phase shown in the response wraps to remain in the range defined by PhaseWrappingBranch.

• "off", 0, or false — Disable phase wrapping.

• The default phase-wrapping configuration depends on the toolbox preferences. For more information, see Specify Toolbox Preferences for Linear Analysis Plots.

• When both phase wrapping and phase matching are enabled, the software performs the phase matching followed by the phase wrapping.

• This value is ignored when PhaseMatchingEnabled is "off".

• The default phase-wrapping configuration depends on the toolbox preferences. For more information, see Specify Toolbox Preferences for Linear Analysis Plots.

• "on", 1, or true — Enable phase matching such that the phase response matches the value specified in PhaseMatchingValue at the frequency specified in PhaseMatchingFrequency. The remaining phase response shifts to maintain the same phase profile.

• "off", 0, or false — Disable phase matching.

• "on", 1, or true — Set the minimum gain for plotting to the MinimumGainValue property value.

• "off", 0, or false — Set the minimum gain for plotting automatically based on the system dynamics.

• To apply the minimum gain value, set the MinimumGainEnabled property to "on".

• The default minimum-gain configuration depends on the toolbox preferences. For more information, see Specify Toolbox Preferences for Linear Analysis Plots.

• "on", 1, or true — Display the chart.

• "off", 0, or false — Hide the chart without deleting it. You still can access the properties of chart when it is not visible.

• "none" — Do not group inputs or outputs.

• "inputs" — Group only inputs.

• "outputs" — Group only outputs.

• "all" — Group all input-output pairs.

• "on", 1, or true — Display the corresponding input.

• "off", 0, or false — Hide the corresponding input.

• "on", 1, or true — Display the corresponding output.

• "off", 0, or false — Hide the corresponding output.

Open Live Script

rng("default")sys = rss(5);bp = bodeplot(sys);

bp.FrequencyUnit = "Hz";bp.PhaseVisible = "off";

Open Live Script

opts = bodeoptions;

opts.Title.FontSize = 15;opts.Title.Color = [1 0 0];opts.Title.String = 'System Frequency Response';opts.FreqUnits = 'Hz';

bodeplot(tf(1,[1,1]),opts);

Open Live Script

sys = tf([1 0.1 7.5],[1 0.12 9 0 0]);

bp = bodeplot(sys);bp.FrequencyScale = "linear";title("Bode Plot of Transfer Function");grid on

Open Live Script

J = [8 -3 -3; -3 8 -3; -3 -3 8];F = 0.2*eye(3);A = -J\F;B = inv(J);C = eye(3);D = 0;sys_mimo = ss(A,B,C,D);size(sys_mimo)

State-space model with 3 outputs, 3 inputs, and 3 states.

bp = bodeplot(sys_mimo);

bp.FrequencyScale = "linear";bp.FrequencyUnit = "Hz";grid on

Open Live Script

sys = tf(1,[1 1]); bp = bodeplot(sys);

bp.PhaseMatchingEnabled = "on"; bp.PhaseMatchingFrequency = 1; bp.PhaseMatchingValue = 150;

This example uses:

• System Identification ToolboxSystem Identification Toolbox

Open Live Script

load iddata1sys1 = n4sid(z1,2); sys2 = n4sid(z1,6);

bodeplot(sys1,'r',sys2,'b');legend('sys1','sys2');

w = linspace(8,10*pi,256);bp = bodeplot(sys1,sys2,w);legend('sys1','sys2');

bp.PhaseMatchingEnabled = "on";bp.Characteristics.ConfidenceRegion.NumberOfStandardDeviations = 2;bp.Characteristics.ConfidenceRegion.Visible = "on";

This example uses:

• System Identification ToolboxSystem Identification Toolbox

Open Live Script

load iddata2 z2;w = linspace(0,10*pi,128);sys_np = spa(z2,[],w);sys_p = tfest(z2,2);

bp = bodeplot(sys_p,sys_np,w);bp.PhaseMatchingEnabled = "on";grid onlegend('Parametric Model','Non-Parametric model');