Hot end temperature control February 08, 2014 07:21PM |
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Re: Hot end temperature control February 09, 2014 04:35AM |
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Re: Hot end temperature control February 09, 2014 06:35AM |
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Re: Hot end temperature control February 09, 2014 03:42PM |
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Re: Hot end temperature control February 10, 2014 12:25PM |
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Re: Hot end temperature control February 10, 2014 12:44PM |
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Re: Hot end temperature control February 10, 2014 01:09PM |
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Re: Hot end temperature control February 10, 2014 01:20PM |
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Re: Hot end temperature control February 10, 2014 01:43PM |
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Re: Hot end temperature control February 10, 2014 05:19PM |
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Re: Hot end temperature control February 11, 2014 04:09AM |
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Re: Hot end temperature control February 11, 2014 04:22AM |
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Quote
rayhicks
Ambient is around 22°C, target temperature is 200°C: Dropping the I term to 0.022 reduced the overshoot, but left a little more ringing and finally settled slightly below the target (200°C) - I increased to I= 0.021 and increased P to 22 (after a couple of trials), now the overshoot is around 2 degrees, and it settles at 199.7+/- 0.2 within around 10 seconds...
or so I thought until I did repeat - it looks as though there's a long-term effect on the final output based on the initial error -
...
btw Before updating, my nozzle temperature was fairly persistently below the set point by around 3-5K
Re: Hot end temperature control February 11, 2014 05:49AM |
Registered: 10 years ago Posts: 578 |
Quote
dc42
If the ringing is too high then you should decrease the P-term. If your starting temperature is high then expect the temperature to settle a few degrees low initially, because the I-term will not have time to reach the required value during the heating phase. But it will slowly climb to the set temperature. Your earlier problem with the nozzle being persistently below the set point was caused by the I term being sampled at too low a value in the old firmware.
One thing I may try is using two different values of Ki: a low one initially, then a much higher one when the temperature gets close to target and the PID is operating in its linear range. This would mean that if the temperature does initially settle a few degrees off target, it would revert to target faster.
Re: Hot end temperature control February 11, 2014 06:49AM |
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Re: Hot end temperature control February 11, 2014 01:49PM |
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Re: Hot end temperature control February 11, 2014 01:59PM |
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Re: Hot end temperature control February 13, 2014 07:06AM |
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Re: Hot end temperature control February 13, 2014 07:48AM |
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Re: Hot end temperature control February 13, 2014 09:04AM |
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Re: Hot end temperature control February 16, 2014 12:33PM |
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Re: Hot end temperature control March 05, 2014 04:51PM |
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Quote
dc42
Yes the controller does clamp the I term. However, the I term was being clamped at far too low a value, so that if the commanded temperature was greater than about 100C, it would never be held, because a substantial P term was needed to keep the controller in the steady state. The controller was effectively a PD controller except at low temperatures.
Re: Hot end temperature control March 05, 2014 05:12PM |
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Re: Hot end temperature control March 06, 2014 04:27AM |
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Re: Hot end temperature control March 06, 2014 05:09AM |
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