To provide a control method for an AC servomotor which can detect a state in which the position feedback signal of the AC servomotor with a position detector is not being transmitted correctly.
Difference between a signal data of an absolute encoder and a count data of an incremental encoder which are outputted from an AC servomotor 1 is detected by a counter comparison means 5 and the result of the counter comparison means 5 is stored in a storage means 6. The memory data stored in the storage means 6 is compared with the result of the counter comparison means 5 by a data comparison means 7. If the result of the data comparison means 7 exceeds a certain value set by an abnormality detection means 8, it is decided by the abnormality detection means 8 that a position feedback signal is not being transmitted correctly.
INOUE HIROYUKI
YOSHINO SHINJI
MASUDA KENICHI
ONISHI YASUHIRO
