Determining relative extreme values of signal for detecting shaft position of DC motor - comparing signal with maximum-minimum and minimum-minimum difference values to detect signal subject to noise pulses

摘要

The maximum amplitude difference (A1-A3) is determined between successive signals produced by detectors of relative minimum and maximum values. A minimum difference (B1-B3) is determined between successive relative maxima and minima and maximum-minimum (A2min;A3min) and minimum-minimum (B2min;B3min) differences are derived using a factor between 0 and 1. The maximum detector responds when the signal exceeds or equals the maximum-minimum difference following a minimum and finally becomes less than the minimum-minimum difference. The minimum detector responds when the signal becomes less than the minimum-minimum difference then larger than the maximum-minimum difference following a maximum. USE/ADVANTAGE - Esp. for measuring drive shaft position in multipole d.c. servo motor. Reliable extreme value detection is achieved even when using effective noise suppression.