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-
-
- Program: A practical control simulation program for
- educational purposes.
-
- Requirements: An Amiga.
-
- Author: Mika Korpela. email: mkorpela@vip.fi
-
-
-
- ABOUT THE PROGRAM...
-
- This control simulation program differs from conventional simulation
- programs in two important aspects: firstly, it does the simulation
- in real-time, and secondly, it imitates the true digital control by
- using 12 bits resolution in input (measuring) as well as in output
- (controlling). That makes it a unique tool to study the control
- behaviour exactly as it is experienced in practice. So, this program
- shows you how the practical system is reacting when you change the
- set value, make load changes, manipulate the control parameters and
- so on.
-
- The program provides two control laws, the traditional PID-control
- and the newcomer, FUZZY CONTROL. You can switch between them using
- the "Control law"-item in "Change?"-menu.
-
- The control task chosen was to control the level in a liquid
- tank by manipulating the input flow to the tank. I chose this
- task because it's common and also simple enough to be simulated
- accurately. So, I guarantee that what you see happening in this
- program is 100% TRUE.
-
- The program uses its own custom screen and it offers several
- windows to perform the user actions:
-
- * the main window which shows the process frame and displays the
- current state of the process
-
- * the control panel window for changing parameter values, set value,
- control output and so on
-
- * the history window which shows the control behaviour way back
- across 540 control steps
-
- * the window for the membership functions (in fuzzy mode)
-
- * the window to show the control rules (in fuzzy mode)
-
- * the window to show the control valve characteristics.
-
-
-
- HOW TO USE THE PROGRAM...(EXAMPLES)
-
- * To see how the control system recovers from load changes,
- follow this procedure:
-
- 1) Choose the "Restart"-item from the "Continue?"-menu.
-
- 2) Switch to AUTO mode by clicking the "MANU/AUTO"-button.
-
- 3) Switch to FAST mode by using the "SLOW/FAST"-button.
-
- 4) Wait until the level and the control output settle down and
- then set the output valve to position 10%.
-
- 5) Repeat the step 4) except now setting the output valve
- fully open.
-
- 6) Wait until the system settles down and then click the
- "show history"-button to see the result.
-
- * Fuzzy control system can be made to oscillate very easely. To do so,
- follow this procedure:
-
- 1) Switch to fuzzy control mode by using the "Control law"-item
- in the "Change?"-menu.
-
- 2) Choose the "Membership functions"-item in the "Fuzzy"-menu.
-
- 3) Compress the membership functions for "error signal" to the
- highest level by using the "compress"-button.
-
- 4) Expand the membership functions for "change in error signal"
- to the highest level by using the "expand"-button.
-
- 5) Close the window to return to the main window.
-
- 6) Switch to AUTO mode by clicking the "MANU/AUTO"-button.
-
- 7) Switch to FAST mode by using the "SLOW/FAST"-button.
-
- 8) Click the "show history"-button after a while to see the
- oscillation.
-
- * To produce the step response for the process, follow this procedure:
-
- 1) Choose the "Restart"-item from the "Continue?"-menu.
-
- 2) Click the "control output"-button to open the control panel
- window.
-
- 3) Increase the control output by clicking the "+++"-button.
-
- 5) Click the "enter"-button.
-
- 6) Switch to FAST mode by using the "SLOW/FAST"-button and
- setting the "stop after delay" to 500.
-
- 7) Wait the history window to appear and you will see
- the step response in all its glory.
-
-
- ---------------------------------------------------------------------
-
-
- Mika Korpela
- Markkinakatu 2
- 33250 Tampere
- Finland
-
- Email: mkorpela@vip.fi
-
-
-