Peter Nachtwey
Member
I agree that things should be a simple as possible. KISS applies. That is why we have auto tuning and ONE slider bar that adjusts all the closed loop gains. How the gains are calculated is hidden from the user. Adjusting one slider bar is MUCH simpler than tweaking gains.
The operators don't need to be experts. The people making the systems are or should be and should hide the complexity in their software or firmware.
As far as errors in modeling go, the model doesn't need to be perfect. In fact it is NEVER perfect. It it was then closed loop control wouldn't be necessary. Feed forwards are based by the open loop model. If I can estimate the model within 5% that means the closed loop part only needs to have enough error to generate the last 5%. On a system with feed forwards but only proportional control, this reduces the error by a factor of 20. If my model is only able to estimate the control output with 50% then at least the closed loop part only needs to make up the last 50 reducing the error by 2 which is a lot better than nothing.
The operators don't need to be experts. The people making the systems are or should be and should hide the complexity in their software or firmware.
As far as errors in modeling go, the model doesn't need to be perfect. In fact it is NEVER perfect. It it was then closed loop control wouldn't be necessary. Feed forwards are based by the open loop model. If I can estimate the model within 5% that means the closed loop part only needs to have enough error to generate the last 5%. On a system with feed forwards but only proportional control, this reduces the error by a factor of 20. If my model is only able to estimate the control output with 50% then at least the closed loop part only needs to make up the last 50 reducing the error by 2 which is a lot better than nothing.
If so then how does floating control deal with these changes when the integrator is so slow? The must be more to the control than just floating control. Didn't you have a proprietary formula that you use in addition to floating control that is more of an estimate like a feed forward?Each of these factors will vary continuously in the typical treatment plant, with 2:1 ratios on a good day and 4:1 or 5:1 common occurrences.