Feedback switching device and method for driving of servo motor

A feedback switching method applied to a drive control loop for a servo motor, wherein the servo motor initially operates at a low rotating speed, the method comprising the steps of:

• (1) using a current sensor to sense a current supplied to the servo motor and outputting a current feedback signal corresponding to the sensed current, using a position sensor to sense a position of the servo motor and outputting a position sensing signal corresponding to the sensed position, and using a position estimator to receive the current feedback signal and output a position estimation signal corresponding to the current feedback signal;
• (2) using a speed calculation module to receive the position sensing signal outputted from the position sensor and the position estimation signal outputted from the position estimator and to generate a first speed signal and a second speed signal corresponding to the position sensing signal and the position estimation signal, respectively, and using a comparison module to receive the first and second speed signals;
• (3) using the comparison module to compare the first speed signal with a preset switching condition, to determine whether the first speed signal is higher than the preset switching condition, if yes, the process goes to step (4), otherwise, the process goes to step (6);
• (4) using a switching module to output the position estimation signal as a position feedback signal;
• (5) using the comparison module to compare the second speed signal with the preset switching condition, to determine whether the second speed signal is lower than the preset switching condition, if yes, the process goes to step (6), otherwise, the process goes to step (4);
• and
• (6) using the switching module to output the position sensing signal as the position feedback signal.

A feedback switching method applied to a drive control loop for a servo motor, wherein the servo motor initially operates at a high rotating speed, the method comprising the steps of:

• (1) using a current sensor to sense a current supplied to the servo motor and outputting a current feedback signal corresponding to the sensed current, using a position sensor to sense a position of the servo motor and outputting a position sensing signal corresponding to the sensed position, and using a position estimator to receive the current feedback signal and output a position estimation signal corresponding to the current feedback signal;
• (2) using a speed calculation module to receive the position sensing signal outputted from the position sensor and the position estimation signal outputted from the position estimator and to generate a first speed signal and a second speed signal corresponding to the position sensing signal and the position estimation signal, respectively, and using a comparison module to receive the first and second speed signals;
• (3) using the comparison module to compare the second speed signal with a preset switching condition, to determine whether the second speed signal is lower than the preset switching condition, if yes, the process goes to step (4), otherwise, the process goes to step (6);
• (4) using a switching module to output the position sensing signal as a position feedback signal;
• (5) using the comparison module to compare the first speed signal with the preset switching condition, to determine whether the first speed signal is higher than the preset switching condition, if yes, the process goes to step (6), otherwise, the process goes to step (4);
• and
• (6) using the switching module to output the position estimation signal as the position feedback signal.