Patent ID: 8525465

Claim:
A feedback switching device applied to a drive control loop for a servo motor, comprising: a current sensor for sensing a current supplied to the servo motor and outputting a current feedback signal corresponding to the sensed current; a position sensor for sensing a position of the servo motor and outputting a position sensing signal corresponding to the sensed position; a position estimator for receiving the current feedback signal and outputting a position estimation signal corresponding to the current feedback signal; and a feedback switching comparator for receiving the position sensing signal and the position estimation signal and outputting one of the position sensing signal and the position estimation signal as a position feedback signal according to a preset switching condition; wherein the feedback switching comparator comprises: a speed calculation module for receiving the position sensing signal outputted from the position sensor and the position estimation signal outputted from the position estimator and generating a first speed signal and a second speed signal corresponding to the position sensing signal and the position estimation signal, respectively; as comparison module for receiving the first speed signal and the second speed signal and comparing one of the first and second speed signals with the preset switching condition so as to output a comparison result; and a switching module for receiving the position sensing signal outputted from the position sensor and the position estimation signal outputted from the position estimator and outputting one of the position sensing signal and the position estimation signal as the position feedback signal according to the comparison result.