Frequency-locked stepping position control system

A frequency-locked stepping position control system for driving a stepping motor, comprising:

• a means for driving the stepping motor by a driving signal with a first frequency, to move an object toward a target indicated by an external input command;
• a means for detecting the position of the object to generate a position signal representing the position of the object;
• a means for position-to-frequency converting the position signal into a feedback signal with a second frequency that corresponds to the position of the object;
• a means for comparing the second frequency of the feedback signal with a third frequency of an input signal to generate an error signal with a fourth frequency that is the same as the difference of the second frequency and the third frequency;
• a microprocessor for generating the input signal corresponding to the external input command, generating a first time-base signal and a second time-base signal, and generating a control signal;
• a means for tracking the control signal from the microprocessor to generate a pump slope constant;
• a means for consecutively sampling the error signal by the first time-base signal and the second time-base signal, wherein the error signal sampled by the first time-base signal is applied to the microprocessor to generate the control signal;
• a slope-varied converter for varying a pump voltage according to the sampled error signal from the sampling means and the pump slope constant;
• and
• a means for voltage-to-frequency converting the pump voltage into the driving signal, wherein the first frequency of the driving signal is proportional to the pump voltage.