| ??? 02/20/05 17:30 Read: times |
#88013 - Re: Averaging. Responding to: ???'s previous message |
Dear Kai,
Thanks for your reply, Yes, this is a good idea to simplify the calculation, provided it gives a good fit to the actual curve.
Maybe it's not a good idea to adhere to the pure theoretical data, because this might not take into account some additional effects being responsible for the unlinearity, maybe some unlinearity in the thyristor driver or transformer? Why not taking your measured data (originally taken in laboratory) as theoretical data and puting this into the table? Maybe deviations are smaller if you take from this table the trend later? Kai, I agree it would be much better if my controller measures the prcatical current data from machine it is installed onto and put the table in SEEPROM but the problem these welding currents are so high my caliberation routine can't fire multiple cycles for caliberation purpose I mean it is possible to fire 3 cycles a maximum, minimum and a middle one. But not possible to fire many to get a good practical table. Its possible to force the caliberation in multiple steps with pauses in between to let the things cool down and have many readings for table construction but no other brand seems to be using multi firing caliberation. You should additionally have some protection against calibration errors. Could you store into the serial EEPROM more than one set of calibration points and take the average when corretcing the curve? You could also periodically put a new set of calibration points into the serial EEPROM, while dropping the oldest set. By taking the average of these sets of calibration points you have both, a protection against deserters and a calibration which includes long term drift of machine. The moving average method you discussed is really a great one I will surely use this method where in my controller can go on taking new measured data and keep discarding older ones. Thanks & Regards, Prahlad Purohit |
