Q. Can I see this HTML manual from within RLTOOL?
A. On *nix systems, you can set your default browser path in
``Settings ®browser path''. Click on ``Help ®HTML manual'' to load this html manual in your favourite browser. I do
not know how to implement this for windows. If you do, please get in
touch with me.
Q. What sort of plants does RLTOOL handle?
A. RLTOOL, ver 1.6 handles real valued SISO continuous time plants
(proper scalar transfer functions).
Q. How do I enter transfer functions for RLTOOL?
A. The default value is 1/s. You can change this by editing the
numerator and denominator. You should enter these as polynomials in
s. For example, 3s2+2s+5 should be entered as 3*s2+2*s+5.
Q. My rootlocus plot shows "hanging" incomplete lines, what should I
do?
A. You need to increase the maximum allowable gain. To do this, write
the appropriate value in Settings --> Rootlocus.
Q. I can't make out details on my rootlocus plot, what should I do?
A. Use the zoom utility for a bigger picture. Alternately, reduce the maximum allowed gain and you would get a more detailed plot.
Q. Though I don't click on a open loop pole/zero, the mouse handler reads the click as a open loop pole/zero, what should I do?
A. This happens because of tolerances set in RLTOOL. You can change the tolerances in Limits() macro. Alternately, ZOOM the
region before selecting the point.
Q. Why is my Nyquist plot drawn only for positive frequencies? Why is it coarse?
A. This is the default. You can put the lower limit of frequency as -1000 Hz for instance and you would get a symmetric Nyquist plot.
If it is too coarse, reduce the step size. This can be found in
Settings --> Nyquist plot.
Q. I can't UNDO changes to my plant, what should I do?
A. RLTOOL requires to save your configuration details in a file called .rltoolcfg.sci. This is located in your present working directory.
If you don't have write permissions in your present working directory,
a warning message is displayed and you can't use the UNDO feature.
Q. Which dynamic responses can I see?
A. You can view the following CLOSED LOOP responses: IMPULSE, STEP, RAMP, ARBITRARY INPUT.
Click on Response --> Dynamic to select the "operating point" on the
rootlocus. You will then see a pop-up window which will prompt
you to select the desired plot.
Q. Can I simulate with any arbitrary inputs?
A. No! At present you can simulate with inputs that are (1) piece-wise linear (2) continuous (3) single-valued. You will receive an
error message if your input is not of this type.
Q. Can I change the size of the plotting frame in defining the
arbitrary input?
A. Yes, click on Edit->size in the plotting frame. Enter the required x and y co-ordinates. The default is x=[0,1], y=[0,1]. You may
change these as required.
Q. My step/ramp/impulse response is incomplete/coarse, what should I do?
A. You need to set parameters for maximum time for incomplete response. For a finer resolution, decrease the step size. These
settings are located at Settings --> Dynamic response.
Q. Sometimes I see an error message while plotting the step response/ frequency response why is this? What should I do about it?
A. This happens when the pole and zero are too close by and the mouse handler can't distinguish between the two points. When pole
and zero are close by, zoom the region by the ZOOM utility before selecting a point (gain).
Q. What should I do if I get a warning/error message?
A. Look up the quick reference on errors or warnings in RLTOOL. It will probably help you remove your error.
Q. I think I have found a bug, what should I do?
A. Please mail the bug report to ishan[AT]iitbombay.org. I would appreciate if you also let me know the remedy. It will help improve
RLTOOL.
Q. My RLTOOL crashes , what should I do?
A. Mail your "plant" along with the explicit details to the author. It will help improve RLTOOL.
Q. I would like the feature XYZ to be in RLTOOL, what should I do?
A. Code it into RLTOOL and submit a fresh update. Alternately, let me know about it by e-mail. I shall try to add that feature
sometime...
END OF FAQ.