Method of calibrating a step motor

A method for calibrating d.c. offset and amplitude adjustment means of a microstep motor including a step motor having a plurality of stator coils, a pair of drivers for applying respective driving voltages to said stator coils, a pair of electrical signal sources coupled to respective ones of said drivers for supplying said driving voltages thereto, a pair of said amplitude adjustment means each coupled to a respective one of the electrical signal sources for adjusting amplitudes of the respective driving voltages, and a pair of said d.c. offset adjustment means each coupled to a respective one of the electrical signal sources for adjusting d.c. offsets of the respective driving voltages;

• the method comprising the steps of:
• (a) adjusting at least one of the amplitude adjustment means a predetermined amount so as to produce a signal having a specified amplitude,
• (b) measuring an imbalance of the motor by an accelerometer,
• (c) adjusting the d.c. offset and amplitude adjustment means as required in order to reduce the imbalance measured in (b), and
• (d) iteratively repeating steps (b) and (c) as required until no further reduction in the measured imbalance is possible so as to compensate for non-linearities associated with said coils.

A method for calibrating a microstep motor, comprising the steps of:

• providing a step motor having a plurality of stator coils;
• providing a plurality of drivers for applying respective driving voltages to said stator coils;
• providing a plurality of electrical signal sources each coupled to a respective driver for supplying driving voltages thereto;
• providing a plurality of amplitude adjustment means and connecting each of said amplitude adjustment means between the respective driver and the respective electrical signal source for adjusting amplitudes of the respective driving voltages;
• providing a plurality of d.c. offset adjustment means and connecting each of said d.c. offset adjustment means to a respective electrical signal source for adjusting d.c. offsets of the respective driving voltages;
• and
• calibrating the d.c. offset and amplitude adjustment means,
• said calibrating step including the following steps:
• measuring initial imbalance of the motor,
• adjusting at least one of the amplitude adjustment means a predetermined amount so as to produce a signal having a specified amplitude and applying said signal to the respective driver for suppling a predetermined driving signal to the step motor,
• measuring a new imbalance of the motor,
• adjusting the d.c. offset and amplitude adjustment means to supply adjusted driving signals to the motor as required in order to reduce the measured imbalance, and
• iteratively repeating the d.c. offset and amplitude adjustments as required until no further reduction in the measured imbalance is possible thereby calibrating the d.c. offset and amplitude adjustment means to compensate for non-linearities associated with said coils.