On 13 April 2011 01:20, Dave <[email protected]> wrote: > What is the L term?
Sorry, I didn't explain. L was so obviously "The value of the combined PI limit" in my head that I forgot to explain it. > Many or most of the PID loops that I work with (usually for process > control systems) have anti reset windup implemented such that once the > PID output hits it's limit in a positive or negative direction, > the I term is not allowed to integrate any further. > > Does the scheme you describe work differently? Yes, though not necessarily better. In this scheme, if the P output alone is enough to hit the maximum limit, then I is clamped to zero. I only starts to increase once the Pgain alone is no longer enough to hit the output limit. I might mess about with spreadsheets this lunchtime to see how the differing approaches work in practice. My feeling is that the fact that I can start to increase before the setpoint will tend to speed up the final approach to the setpoint, possibly at the expense of some overshoot. -- atp "Torque wrenches are for the obedience of fools and the guidance of wise men" ------------------------------------------------------------------------------ Forrester Wave Report - Recovery time is now measured in hours and minutes not days. Key insights are discussed in the 2010 Forrester Wave Report as part of an in-depth evaluation of disaster recovery service providers. Forrester found the best-in-class provider in terms of services and vision. Read this report now! http://p.sf.net/sfu/ibm-webcastpromo _______________________________________________ Emc-developers mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/emc-developers
