LineWidth - specifies the width (in points) of the line.You can also specify other line characteristics using graphics properties (see line for a description of these properties): See LineSpec for more information on specifying line styles and colors.See the "Creating 2-D Graphs" and "Labeling Graphs" in Using MATLAB Graphics for more information on plotting.Sets the default ColorOrder to use only the color black and sets the LineStyleOrder to use solid, dash-dot, dash-dash, and dotted line styles. If you want changes you make to these properties to persist, then you must define these changes as default values. Note that, by default, MATLAB resets the ColorOrder and LineStyleOrder properties each time you call plot. After cycling through all the colors defined by ColorOrder, plot then cycles through the line styles defined in the axes LineStyleOrder property. If you do not specify a color when plotting more than one line, plot automatically cycles through the colors in the order specified by the current axes ColorOrder property. Returns a column vector of handles to line graphics objects, one handle per line. (See the "Examples" section for examples.) Sets properties to the specified property values for all line graphics objects created by plot. You can mix Xn,Yn,LineSpec triples with Xn,Yn pairs: plot(X1,Y1,X2,Y2,LineSpec,X3,Y3). Plots all lines defined by the Xn,Yn,LineSpec triples, where LineSpec is a line specification that determines line type, marker symbol, and color of the plotted lines. If only Xn or Yn is a matrix, the vector is plotted versus the rows or columns of the matrix, depending on whether the vector's row or column dimension matches the matrix. Plots all lines defined by Xn versus Yn pairs. In all other uses of plot, the imaginary component is ignored. If Y is complex, plot(Y) is equivalent to plot(real(Y),imag(Y)). Plots the columns of Y versus their index if Y is a real number. at this point shows the system phase marginįor more comprehensive understanding, see the solved Example for Bode Plot using Matlab.Plot (MATLAB Functions) MATLAB Function Reference At same point, obtain the phase response.Find the point, where system’s open loop amplitude crosses 0 dB.The distance below 0dB at this point shows the system gain margin.At some point obtain amplitude response.Find the point, where system phase response crosses -180.Which will cause marginal stability of a system. It can be described as an increase in the open-loop system gain |GH (jω)| when system phase is at 180. Phase and gain margin are usually measured from open loop response and cannot be obtained from the frequency response of a closed loop system directly. This distance can be measured in terms called phase margin and gain margin.
How far -1 is from open loop transfer function GH (jω) measures the stability of a system. The characteristic equation of a typical system can be written as, It is the frequency at which amplitude ratio becomes 1 or log modulus of transfer function becomes 0. It is the frequency, where phase shift becomes -180 o. There are certain terms, which we need to familiar with to fully understand the bode plot. Wn = 2*pi*fn % Natural frequency conversion in rad/sįig.6: Plot for Second Order System Special Terms
Here, we implemented the bode plot of a second-order network for the comprehensive understanding of the readers. Which means that phase plot would be a straight line with -90. $G\left( j\omega \right)H\left( j\omega \right)=K$ For gain factor K, the bode-plot is obtained as: We will discuss above elementary factors one by one: Gain factor KĪ constant K may be considered as complex number expressed in polar form with magnitude K and angle 0. The Bode plot or diagram of a transfer function can be constructed by combining the transfer functions of following elementary factors. In bode-plot, low-frequency asymptote (that is ω>1/T) cut off at 0 decibels (dB) line where ω=1/T, that is the frequency called corner frequency or break point. A third advantage results from the introduction of logarithms, thus reducing the process of multiplying two transfer functions to addition.A second advantage is that this technique is feasible for lower frequencies, where measuring the phase difference between input and output signals is difficult.One apparent advantage of the bode diagram is the relative ease with which it is obtained.At times, the magnitude of a transfer function is referred to as gain and the corresponding plot as a gain plot. The magnitude of the transfer function is expressed in decibels (dB), the phase in degrees and the common parameter of frequency is plotted on a logarithmic scale in radians.
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