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PIDStepL settings

Created by: Dan Rubtcov at: 5/28/2013 2:22 PM (7 Replies)

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5/28/2013 2:22 PM	Rate (0)
Dan Rubtcov Advanced Member Joined: 12/19/2012 Last visit: 8/1/2024 Posts: 9 Rating: (0)	Hi, All. I used PID controller with 2 digital output and analog feedback by positioning (0-100%). The type is "PIDStepL" from APL Libraries(FB 1878). PID controls position of valve. Valve's type is "integrating". Normal controller's mode is "Manual". Operator just sets valve's position that he needs( 0-100%). Minimum valve's step is 0.8% (it is received from experiments). The problem - it is impossible to reach positioning accuracy less then 2-3%. How can I increase positioning accuracy ? Regulator's settings: - Motor time=30 sec - PulseTime=0.3 sec - BreakTime=0.5 sec - I don't know on what it influences... Call's period PID controller is 100ms. Thanks for responses...

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5/28/2013 8:53 PM	Rate (0)
hdhosseini Diamond Member Joined: 1/28/2009 Last visit: 1/17/2025 Posts: 6858 Rating: (1366)	Dan Rubcov Hi, All. I used PID controller with 2 digital output and analog feedback by positioning (0-100%). The type is "PIDStepL" from APL Libraries(FB 1878). PID controls position of valve. Valve's type is "integrating". Normal controller's mode is "Manual". Operator just sets valve's position that he needs( 0-100%). Minimum valve's step is 0.8% (it is received from experiments). The problem - it is impossible to reach positioning accuracy less then 2-3%. How can I increase positioning accuracy ? Regulator's settings: - Motor time=30 sec - PulseTime=0.3 sec - BreakTime=0.5 sec - I don't know on what it influences... Call's period PID controller is 100ms. Thanks for responses... Hello, Integrating actuators are generally considered as cheaper and their limitations in accuracy were accepted in practice compared to intelligent actuators.I think the best consultant on accuracy of these actuators would be its manufacturer. Best regards Hamid Hosseini
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5/29/2013 10:22 AM	Rate (0)
Dan Rubtcov Advanced Member Joined: 12/19/2012 Last visit: 8/1/2024 Posts: 9 Rating: (0)	Ok, thanks...

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5/29/2013 12:16 PM	Rate (0)
TerminalBuzz Silver Member Joined: 11/4/2011 Last visit: 1/19/2025 Posts: 253 Rating: (53)	I had similar problem and I've got to put PulseGen after PIDStepL to get the 1% precision and get rid of jumping of the control valve position. PIDStepL is sending the difference between Setpoint and Position value to PulseGen. PulseGen is controlling the VlvMotL.

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This contribution was helpful to 1 thankful Users Dan Rubtcov

5/30/2013 7:55 AM	Rate (0)
Dan Rubtcov Advanced Member Joined: 12/19/2012 Last visit: 8/1/2024 Posts: 9 Rating: (0)	TerminalBuzz I had similar problem and I've got to put PulseGen after PIDStepL to get the 1% precision and get rid of jumping of the control valve position. PIDStepL is sending the difference between Setpoint and Position value to PulseGen. PulseGen is controlling the VlvMotL. Hi TerminalBuzz, thanks for response... As far as I understood what you mean is see attachment So, do I need to perform pulse-duration modulation by "PULSEGEN" ? Where pulse frequency is function from an error by positioning of valve ? Attachment chart1gif_5215372_8088949.gif (369 Downloads)
	Last edited by: O_Moderator at: 5/31/2013 9:08 AM picture trasnferred to attachment
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6/3/2013 11:32 AM	Rate (0)
TerminalBuzz Silver Member Joined: 11/4/2011 Last visit: 1/19/2025 Posts: 253 Rating: (53)	Yes, that is how it worked for me

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6/3/2013 3:05 PM	Rate (0)
Dan Rubtcov Advanced Member Joined: 12/19/2012 Last visit: 8/1/2024 Posts: 9 Rating: (0)	Ok, Thanks. I will try to use that regulator's structure on real valve...

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9/2/2013 7:52 AM	Rate (0)
Dan Rubtcov Advanced Member Joined: 12/19/2012 Last visit: 8/1/2024 Posts: 9 Rating: (0)	I can confirm now - it works. I used FB3 (PULSEGEN) in my project. I've reached accuracy about 1% in valve's positioning. However, with valves which are old (big gap in reducer) it was am impossible. Old valves had accuracy bit more then others (up to 1.5-2 %) and significant overshoot (up to 2-3 %). I still don't know how to fix it. Is it possible ?

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