Controls Lab OnLine |
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Assignment 5
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Web-Lab Assignment #5 Sine Response Experiments |
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| 1. Again, we want to investigate the transient response of our system. We still want to do our experimentation in a "linear" range of the operating curve. So again look at your SSOC from Assignment 2 and choose a value in the middle ot the"linear" region and we'll call this the "baseline." The value of the Input (%) for this baseline we call the Input baseline. For example, the Input baseline may be 40%. The corresponding value of the output variable we call the Output baseline. |
| 2. We will have the Input function be sinusoidal function oscillating about the input baseline, all still in the linear operating range. For example if we want to sine-wave to vary from 30% to 50%, the amplitude of the sine is 10%. By the way, the amplitude of the step CAN BE negative (!) if you want it to. There's no reason for it to be, however. |
| 3. The experiment has to run long enough in order to reach a steady oscillation output and to continue for enough cycles for us to get reasonable data. Stated another way, the transients have to die out, then the steady oscillations go on for a few cycles. From our experiences before, we should have some idea of the time required for the transients to die out. In the example given in Assignment 1, we see that at least 5 or 6 seconds needs to pass before the system transient disappear. So, the total length of the experiment needs to be 6 seconds plus about 5*T where T=1/f. "f" is the frequency of the experiment. |
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| 4. The experiment needs to be done for several different frequencies. I suggest that a (radian) frequency to start with would be 1/tau. Where you found tau in Assignment 3. Convert the radian frequency to cycle per second frequency (Hertz) by dividing by 2*PI. Then run the experiment at 1/2, 1/5, 1/10, 1/20, that frequency. Then run the experiment at 2x, 5x, 10x, 20x that initial frequency. |
| 5. When you're ready, click on "Controls Lab Experiments" Choose your system, then "Sine Input Function" |
| 6. Fill in your name, location & email name and then select a "length of experiment" and values of the the other parameters & click the "RUN EXPERIMENT" button. |
| 7. Look at and analyse the graphs. See Smith & Corripio, page 400-401. |
| 8. Conduct enough experiments to construct a Bode plot. See Smith & Corripio, page 400-401. Here is how the Bode plot might look   Click to download an Excel spreadsheet to draw these Bode plots
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| 9. Send an e-mail (report) within the next few days. (Click on "report" to get instructions.) |
**** CONTINUOUS IMPROVEMENT ***
For suggestions and feedback,
contact Jim Henry - Lab-Master Send E-Mail to Jim Henry
7 August 1996, Last revised 15 April 1998
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