Help for RLTOOL.
1. Starting
RLTOOL:
load the rltool library as per instructions in the README file. If
the library loads properly the following message is displayed on Scilab
prompt:
mode(-1);
rltool is loaded;
enter "rlt()" to start
Type rlt() to start this programme.
2. Using RLTOOL:
It is intended to make RLTOOL very user friendly and as such most features
should be obvious. However, these are given below for the sake of completness.
On execution, the user is prompted to enter the transfer function as
numerator / denominator in the variable 's'. The default value is set
to '1/s'. Edit these values and enter polynomials in s. Press OK when
you have entered the transfer function. A Rootlocus plot of the transfer
function is displayed. Open loop poles are shown by crosses and zeros by
circles. Click on any point of the rootlocus plot to know the gain and
closed loop poles corresponding to that point. At any time you can choose
the frequency design mode by clicking on "Design->Frequency".
This displays the magnitude plot of the open loop transfer function. Click
on any point of the magnitude plot to know the magnitude in dB and frequency
in Hz. You can revert back to root locus mode by clicking on "Design->Root
Locus". A choice of various plots is available as below
-
Impulse Response
of the system
g*k/(1+gk) i.e.
with unity feedback. This is available only in Root Locus mode.
Click on "Response->Closed Loop" and the programme
will prompt you to select a point on the rootlocus. A popup window will
ask for the choice of closed loop responses. Click on "Impulse"
to view the impulse response
-
Step Response
of the system g*k/(1+gk) i.e. with
unity
feedback. This is available only in Root Locus mode. Click on "Response->Closed
Loop" and the programme will prompt you to select a point on the
rootlocus. The Step response of the closed loop system is displayed along
with value of gain and location of closed loop poles. You can also view
details like percent peak overshoot, settling time,
peak time etc.
-
Ramp Response of
the system g*k/(1+gk) i.e. with
unity
feedback. This is available only in Root Locus mode. Click on "Response->Closed
loop" and the programme will prompt you to select a point on the
rootlocus. The Ramp response of the closed loop system is displayed along
with value of gain and location of closed loop poles.
-
Arbitrary Input :
RLTOOL allows you to simulate your system g*k/(1+gk)
i.e. with unity feedback with arbitrary inputs which are PIECEWISE
LINEAR and SINGLE VALUED. Click on "Response->Closed
loop" and the programme will prompt you to select a point on the
rootlocus. A popup window will ask for the choice of closed loop responses.
Click on
"Arbitrary" to view an interface
for drawing the input. You can do the following
-
Resize the plot in Edit->Size
-
Undo changes in Edit->Undo
-
Replot/Abort
-
Click on Edit->OK after you have finished
drawing the input
You will now see the response along with the input which you defined. Note
that the input should be single valued, you will receive an error message
if the input is not single-valued.
-
Sinusoidal
input: Plots the dynamic response for the system g*k/(1+gk)
i.e. with unity feedback with input as Input=Asin(wt)
where A is the amplitude and w is the frequency in rad/sec. Click on "Response->Closed
loop" and the programme will prompt you to select a point
on the root locus. A popup window will ask for the choice of closed loop
responses. Select "sinusoidal". The default
input is sin(t) i.e. amplitude=1 and frequency=1 rad/sec. These can be
changed by clicking on "settings" button in
the window. Close the window to return.
-
Sensitivity plot:
Sensitivity Response of g*k/(1+gk).
-
Frequency
Response of the system g*k/(1+gk).
Available in rootlocus mode only. Use is same as above. Click on "Response->Closed
Loop" for closed loop frequency response.
-
Nyquist plot: Available
in Root locus and Frequency modes. Nyquist plot of the open loop plant
is displayed. Click on "Response->Nyquist".
-
Nichols Plot: Nichols(Blacks)
diagram of g
3. Editing
of plants:
-
Undo: You can
undo one change of transfer function. Click on "Edit->
Undo" to cancel your last change. You will
have to select a working directory where you have write permission to use
this feature. The working directory can be set in "Settings->PWD".
-
Add pole: Available in Rootlocus mode.
Click on "Edit->Add Pole". Click on any point
in the complex plane. If you clicked at a real valued point it is selected.
If you clicked at a complex valued point then both the point and its complex
conjugate are selected.
-
Add zero: Available in Rootlocus mode.
Click on "Edit->Add Zero". Click on any point
in the complex plane. If you clicked at a real valued point it is selected.
If you clicked at a complex valued point then both the point and its complex
conjugate are selected.
-
Remove pole: Available in Rootlocus
mode. Click on "Edit->Remove Pole". Click
on any point in the complex plane. If you clicked at a real valued point
it is selected. If you clicked at a complex valued point then both the
point and its complex conjugate are selected.
-
Remove zero: Available in Rootlocus
mode. Click on "Edit->Remove Zero". Click
on any point in the complex plane. If you clicked at a real valued point
it is selected. If you clicked at a complex valued point then both the
point and its complex conjugate are selected.
-
Add Cascade stage: Available in all
modes. Click on "Edit->Add Cascade". You will
be prompted to enter a transfer function. This gets multiplied with your
current open loop transfer function.
-
Remove Cascade stage: Available in all modes.
Click on "Edit->Remove Cascade". You will
be prompted to enter a transfer function. This divides your current open
loop transfer function.
-
Edit Plant: Available in all modes.
Click on "Edit->Edit Plant" to directly edit
your current plant.
4.
Saving and loading plants: -
-
Saving: To save your current plant, click
on "Save->Save". You will be prompted to enter
filename.
-
Loading: To load existing plant from
a file, click on "Save->Load". You will be
prompted to enter the filename.
5. Settings:
RLTOOL allows users to set parameters for plots and simulations. Click
on "Settings" to edit these settings. Press
OK to load these new settigs. Press CANCEL to return. This loads the Default
settings. You have the following settings
-
Dynamic Response Settings (time-step and maximum time)
-
Frequency Response Settings (min frequency, frequency step and maximum
frequency)
-
Maximum gain for Rootlocus
-
Graphics attributes
-
Present working directory
6. Help:
Short online help is provided on many topics.
7. Quit:
Click on "Quit" to quit rltool programme. If you don't see this button
on your graphics panel, pull down your graphics window a bit. You can do
this by dragging down a small black square on the top right corner of the
graphics window. Alternately, close RLTOOL by clicking the "X" mark on
your window.
end of help for RLTOOL
author: Ishan Pendharkar, ishan@ee.iitb.ac.in