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addResponse

Add dynamic system response to existing response plot

Since R2024b

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    Syntax

    addResponse(rp,sys)
    addResponse(rp, sys1,sys2,...,sysN)
    addResponse(___,Name=Value)

    Description

    addResponse(rp,sys) adds the response for dynamic system model sys to the existing response plot associated with chart object rp.

    • The time and frequency specifications for the added response are computed automatically.

    • The line width and color for the response are assigned automatically.

    example

    addResponse(rp, sys1,sys2,...,sysN) add the responses for multiple dynamic system models.

    addResponse(___,Name=Value) configures added responses using one or more name-value arguments.

    Examples

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    Open Live Script

    Create a second-order transfer function with a damping ratio of 0.5.

    wn = 2;
zeta = 0.5;
sys = tf(wn^2,[1,2*zeta*wn,wn^2]);

    Plot the step response of this system.

    sp = stepplot(sys);

    MATLAB figure

    Create a transfer function with a lower damping ratio and add it to the step plot.

    zetaL = 0.25;
sysL = tf(wn^2,[1,2*zetaL*wn,wn^2]);
addResponse(sp,sysL);

    MATLAB figure

    Create a transfer function with a higher damping ratio and add it to the step plot.

    zetaH = 0.75;
sysH = tf(wn^2,[1,2*zetaH*wn,wn^2]);
addResponse(sp,sysH);

    MATLAB figure

    Add a legend to the plot.

    legend("zeta = 0.5","zeta = 0.25","zeta = 0.75",...
    Location="southeast");

    MATLAB figure

    Input Arguments

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    Response plot chart object, specified as one of the following objects:

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

    • Continuous-time or discrete-time numeric LTI models, such as tf, zpk, or ss models.

    • Sparse state-space models, such as sparss or mechss models.

    • Generalized or uncertain LTI models such as genss or uss (Robust Control Toolbox) models. Using uncertain models requires Robust Control Toolbox™ software.

      • For tunable control design blocks, the function evaluates the model at its current value to plot the response.

      • For uncertain control design blocks, the function plots the nominal value and random samples of the model.

    • Frequency-response data models such as frd models. For such models, the function plots the response at the frequencies defined in the model.

    • Identified LTI models, such as idtf (System Identification Toolbox), idss (System Identification Toolbox), or idproc (System Identification Toolbox) models. Using identified models requires System Identification Toolbox™ software.

    • Linear time-varying (ltvss) and linear parameter-varying (lpvss) models.

    Dependencies

    The supported models depend on the type of chart object specified in rp.

    • Frequency-response data models are supported only for bodeplot, nicholsplot, nyquistplot, and sigmaplot chart objects.

    • Linear time-varying and linear parameter-varying models are supported only for stepplot, impulseplot, initialplot, and lsimplot chart objects.

    • For rlocusplot chart objects, only SISO models are supported.

    Name-Value Arguments

    Specify optional pairs of arguments as Name1=Value1,...,NameN=ValueN, where Name is the argument name and Value is the corresponding value. Name-value arguments must appear after other arguments, but the order of the pairs does not matter.

    Example: Color="red" sets the plot color to red.

    Plot Appearance

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    Plot color, specified as an RGB triplet or a hexadecimal color code and stored as an RGB triplet.

    Alternatively, you can specify some common colors by name. The following table lists these colors and their corresponding RGB triplets and hexadecimal color codes.

    Color NameRGB TripletHexadecimal Color Code

    "red" or "r"

    		[1 0 0]#FF0000

    "green" or "g"

    		[0 1 0]#00FF00

    "blue" or "b"

    		[0 0 1]#0000FF

    "cyan" or "c"

    		[0 1 1]#00FFFF

    "magenta" or "m"

    		[1 0 1]#FF00FF

    "yellow" or "y"

    		[1 1 0]#FFFF00

    "black" or "k"

    		[0 0 0]#000000

    "white" or "w"

    		[1 1 1]#FFFFFF

    Line style, specified as one of the following values.

    Line StyleDescription
    "-"Solid line
    "--"Dashed line
    ":"Dotted line
    "-."Dash-dotted line

    Marker style, specified as one of the following values.

    MarkerDescription
    "none"No marker
    "o"Circle
    "+"Plus sign
    "*"Asterisk
    "."Point
    "x"Cross
    "_"Horizontal line
    "|"Vertical line
    "s"Square
    "d"Diamond
    "^"Upward-pointing triangle
    "v"Downward-pointing triangle
    ">"Right-pointing triangle
    "<"Left-pointing triangle
    "p"Pentagram
    "h"Hexagram

    Plot options, specified as one of the following objects, depending on the type of chart object specified in rp.

    Options ObjectChart Object rp
    timeoptionsimpulseplot, initialplot, stepplot, and lsimplot
    bodeoptionsbodeplot
    nicholsoptionsnicholsplot
    nyquistoptionsnyquistplot
    sigmaoptionssigmapplot
    pzoptionspzplot, iopzplot, and rlocusplot
    Step and Impulse Response

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

    • Positive scalar tFinal— Compute the response from t = 0 to t = tFinal.

    • Two-element vector [t0 tFinal] — Compute the response from t = t0 to t = tFinal. (since R2023b)

    • Vector Ti:dt:Tf— Compute the response for the time points specified in t.

      • For continuous-time systems, dt is the sample time of a discrete approximation to the continuous system.

      • For discrete-time systems with a specified sample time, dt must match the sample time property Ts of sys.

      • For discrete-time systems with an unspecified sample time (Ts = -1), dt must be 1.

    • [] — Automatically select time values based on system dynamics.

    When you specify a time range using either tFinal or [t0 tFinal]:

    • For continuous-time systems, the function automatically determines the size of the time step and number of points based on the system dynamics.

    • For discrete-time systems with a specified sample time, the function uses the sample time of sys as the step size.

    • For discrete-time systems with unspecified sample time (Ts = -1), the function interprets tFinal as the number of sampling periods to simulate with a sample time of 1 second.

    Express t using the time units specified in the TimeUnit property of sys.

    If you specified a step delay td using Config, the function applies the step at t = t0+td.

    Dependencies

    This argument is supported only when rp is a stepplot object or an impulse object.

    Parameter trajectory of the LPV model, specified as a matrix or a function handle.

    • For exogenous or explicit trajectories, specify p as a matrix with dimensions N-by-Np, where N is the number of time samples and Np is the number of parameters.

      Thus, the row vector p(i,:) contains the parameter values at the ith time step.

    • For endogenous or implicit trajectories, specify p as a function handle of the form p = F(t,x,u) in continuous time and p = F(k,x,u) in discrete time that gives parameters as a function of time t or time sample k, state x, and input u.

      This option is useful when you want to simulate quasi-LPV models. For an example, see Step Response of LPV Model.

    Dependencies

    This argument is supported only when sys is an LPV model and rp is a stepplot object or an impulse object.

    Configuration of the applied signal, specified as a RespConfig object. By default, step applies an input that goes from 0 to 1 at time t = 0. Use this input argument to change the configuration of the step input. See Response to Custom Step Input for an example.

    For lpvss and ltvss models with offsets (x0(t),u0(t)), you can use RespConfig to define the input relative to u0(t,p) and initialize the simulation with the state x0(t,p).

    This argument is supported only when rp is a stepplot object or an impulse object.

    Dependencies

    This argument is supported only when rp is a stepplot object or an impulse object.

    Frequency Response

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

    • Cell array of the form {wmin,wmax} — Compute the response at frequencies in the range from wmin to wmax. If wmax is greater than the Nyquist frequency of sys, the response is computed only up to the Nyquist frequency.

    • Vector of frequencies — Compute the response at each specified frequency. For example, use logspace to generate a row vector with logarithmically spaced frequency values. The vector w can contain both positive and negative frequencies.

    • [] — Automatically select frequencies based on system dynamics.

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

    • Log frequency scale, the plot frequency limits are set to [wmin,wmax] and the plot shows two branches, one for positive frequencies [wmin,wmax] and one for negative frequencies [–wmax,–wmin].

    • Linear frequency scale, the plot frequency limits are set to [–wmax,wmax] and the plot shows a single branch with a symmetric frequency range centered at a frequency value of zero.

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

    Dependencies

    This argument is supported only when rp is a bodeplot,nicholsplot, nyquistplot, or sigmaplot object.

    Version History

    Introduced in R2024b

    See Also

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