Compensate for heating the filament via a function: additional power ~ extrusion feed speed
I would like to know your opinion on the following, Repetier:
You probably know that in Marlin there is the option to add a so-called "Kc" value to the PID routine, which adds a extrusion rate - dependant value to the PID value like this:
PID_value = (Standard PID routine with Kp, Kd, Ki) + (Extrusion feed rate) * Kc
Now, I dont want to ask you to copy Marlin, but I find the basic idea intriguing: When Kc is chosen well, both with PID temperature control and Dead time control, temperature fluctuation caused by (fast) extrusion is basically nullified. Would you be interested in implementing such option into Repetier?
The main requirement for this to be possible though, is a stable possibility to ask for the actual extruder position or speed during the PID evaluation. Only if this is available, a "Kc-like" feature would make sense. Is this possible in Repetier?
And just btw: For 1.75 mm filament (ABS and PLA) it is ~1W for 1 mm/s feed rate (~3W for 3.0 mm filament). At, lets say, 4 mm/s feed rate (10 mm³/s @ 1.75 mm filament) this is 4W - 10% of a 40W heater max, 15% of a 28W heater max. The Kc value is easily calculated if one knows filament width and max. hot end wattage.