6/14/2012 11:02 PM | |
Joined: 1/28/2009 Last visit: 9/10/2024 Posts: 6849 Rating: (1365) |
Hello martinpa, Smith predictor,We have seen that before here with SIMATIC Products: Smith-predictor for processes with long delay timeTo tell you what is exactly wrong with your "Set up" , we need to see your codes.From my point of view,Short (im)pulses on a control valve is not logical to achieve a control strategy and make the service life of the actuator shorten. I just concluded those points from the attachment provided. Hope this helps Best regards, Hamid Hosseini |
This contribution was helpful to1 thankful Users |
6/15/2012 12:07 PM | |
Posts: 5 Rating: (0) |
Hello Hamid, thank you for your answer. Following your advice, I wrote a program on a pdf. I scaled input range of 0 to 6912 in the range 0 to 100% and the output from 0 to 100% of range 0 to 6912. The reference value is in the range from 0 to 100%. OB35 block and function block FB41 are called cyclically every 5s494ms. I tested my code (function blocks - inertia model and dealy model) in matlab and it was correct. Best regards, Marcin Pach. AttachmentOB1 and OB35.pdf (383 Downloads) |
Last edited by: martinpa at: 6/15/2012 12:20 PMLast edited by: martinpa at: 6/15/2012 12:08 PM |
|
6/17/2012 7:31 PM | |
Posts: 5 Rating: (0) |
Thanks Hamind. I'll check your advice tomorrow in the lab. Best regards, Marcin Pach |
6/22/2012 12:12 PM | |
Joined: 1/28/2009 Last visit: 9/10/2024 Posts: 6849 Rating: (1365)
|
Hello martinpa , For an overview of 3-term PID controllers,please check THIS link.Also ,this topic for step response of a casual differentiator, D part accelerate controller response while a jump in error (e.g due to step change in set point) and fade away. diff function of modular PID
This would not be an "always True" statement,it depends on process dynamic and disturbance!Effect of Ti on Control value discussed here:
Hope this helps Best regards Hamid Hosseini |
Follow us on