Hi, Tjaart van der Walt wrote: > > Good advice. I have noticed another thing that can make your > system much more immune to the low-frequency I-oscillations : > Reset the I-value to zero whenever P=0. looks like a good Idea - BTW did you try to optimize your PID-paramters according to Ziegler-Nichols ? I learned that one can achieve a good performance of the PID control by looking for the point where Kp has a value ( no I and D at this moment ) which gives the output a oscilation with a constant amplitude. This Kp is now called Kpcrit(ical). For the optimized PID control now use Kp = 0.45 * Kpcrit, There are also values to multiply Ki and Kd with, but I can't recall them at the moment - you may look them up in a Control-Handbook ( look for Ziegler-Nichols ) someone else tryed it this way ? Kind regards, Stefan