![]() This is why when estimating responses empirically or experimentally people usually use random white noise or sinusoidal chirps with enough frequency content as excitations. Notice that in order to capture all the relevant dynamics, we need to make sure that we excite our system at enough frequency points to get a good trace. This type of frequency response diagram is what is normally called a bode plot. If each of these individual measurements is plotted on its own axis against the corresponding pure tone frequency of the sine wave, it will give us a single point on a frequency response diagram.īy repeating this process for a number of different pure tone frequencies, we can construct a trace for the amplitude variation, also known as the gain of the system, as well as a trace for the phase shift introduced by the system for any given frequency range. But it will not alter its fundamental frequency.Ĭomparing the input and the output sinusoidals, we can measure the change in amplitude and phase shift introduced by the system. Notice that a linear time-invariant system can affect the amplitude of the signal and can introduce a shift in the phase of the sine wave. By definition, if we fit in a pure sinusoidal tone into a generic linear time-invariant system, the output will also be a pure sinusoidal tone. The peak due to the underdamped pole is clearly shown.In this section, we're going to describe what a frequency response diagram is, as well as take a look at their primary characteristics. The program show this with a simple circle showing the ![]() (and zeros) present a difficulty because they cause a peak (dip) in the Pole this is an example when it might be convenient not to show the asymptotic Previous graph, the phase of the asymptotic plot obscured that of the real With the asymptotic plot of the complete transfer function. The plot modified to have thicker lines, a grid, phase in radians and Likewise included or excluded by simply clicking on it. For example, the zero at the origin can be excluded simply by clicking on it in the lower left hand box.Īt the origin is no longer included in the plot. The function displayed can be manipulated term by term to illustrate the effect of each term. Also in the upper left is a "Help" tab.Īlso shown in the upper right hand corner is the transfer function, H(s).A 'Legend' box that shows elements displayed in the plot.Ĭheck-boxes that allow the user to display how the plots are.This box is empty in this display because the diagram displays all three elements of the transfer function. A box that shows elements excluded from the plot.The legend identifying individual terms on the plot.Sometimes it gets in the way of seeing the other plots, so you may Particular there is a check-box that determines whether or not toĭisplay the asymptotic plot for the complete transfer function Several checkboxes that let the user format the image.A list of the systems in the user workspace.The magnitude plot, both the piecewise linear approximation for all three terms as well as theĪsymptotic plot for the complete transfer function and the exact Bode diagram for magnitude.The following MATLAB® commands begin execution of the GUI: >MySys=tf(1000*,) %define Xfer function This function has three terms to be considered when constructing a Bode diagram, a constant (100), a pole at ω=10 ![]() While MATLAB is extremely powerful, it is also very expensive. I have stopped working on BodePlotGui and have developed a similar tool in JavaScript to make it more accessible (see the "Drawing Tool" tab, above). Save it, and then rerun the BodePlotGui.m file. You can edit the size and layout of the GUI for your machine. If you have this problem, simply run the MATLAB command " guide" and open the file BodePlotGui.fig. Note: the MATLAB GUI doesn't display well on all devices (some elements of the GUI may not show up). Is hoped that the BodePlotGui program will be a versatile program for teaching and learning the construction of Bode diagrams from piecewise linear approximations. Takes a transfer function and splits it into its constituent elements, thenĭraws the piecewise linear asymptotic approximation for each element. Graphical user interface written in the MATLAB® programming language. BodePlotGui: A Tool for Generating Asymptotic Bode Diagrams ![]()
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