Method for eliminating position tracking errors in the presence of resolver excitation errors for motion control systems

In a servomotor control system including a resolver integrally coupled to a servomotor and responsive to an excitation signal to provide a return signal indicating the instantaneous angular position of the servomotor, apparatus comprising:

• a source of periodic signal having a predetermined frequency to be used as said excitation signal;
• a source of clock signal;
• means, responsive to said clock signal, for monitoring said excitation signal comprising a comparator which compares said periodic excitation signal in amplitude to a predetermined reference value to generate an output signal, at instants determined by said clock signal, indicting intervals during which said excitation signal may be invalid;
• means for sampling sad return signal to generate a sequence of samples representing a respective sequence of angular position measurements for said servomotor;
• and
• means, responsive to the output signal of the monitoring means, for selectively invalidating ones of said samples generated in intervals during which said excitation signal may be invalid.

A method suitable for use in a servomotor control system which includes a resolver integrally coupled to a servomotor and responsive to an excitation signal to provide a return signal indicating the instantaneous angular position of the servomotor, the method comprising the steps of:

• providing, as said excitation signal, a periodic signal having a predetermined frequency;
• monitoring said excitation signal to generate an invalidating output signal indicating intervals during which said excitation signal may be invalid;
• sampling said return signal to generate a sequence of samples representing a respective sequence of angular position measurements for said servomotor;
• and
• selectively invalidating ones of said samples generated in intervals during which said excitation signal may be invalid, responsive to the invalidating output signal.