Method of controlling a stepper motor

A method of controlling a stepping motor after initiating movement thereof by using motor feedback pulses indicative of motor position comprising the steps of:

• storing at addressable locations in a memory a series of time delay values for motor advance pulses for obtaining a predetermined motor velocity-position profile;
• addressing said locations in response to the occurrence of said feedback pulses for reading out from said locations said delay values corresponding to said feedback pulses;
• and
• generating advance pulses for said motor in response to said time delay values read out from said locations.

Apparatus for controlling the velocity-position profile of a stepping motor comprising:

• a stepping motor;
• means for energizing said motor to step in increments of displacement in response to motor advance pulses;
• means for generating feedback pulses as said motor is displaced predetermined increments of motion;
• storage means having a motion data table with addressable locations having time delay values stored therein for determining the times at which motor advance pulses are to be applied to said energization means after the occurrence of a feedback pulse;
• control means responsive to a said feedback pulse for addressing said storage means and generating a motor advance pulse for said energization means after a time delay corresponding to said feedback pulse.

A current commutating circuit for a stepping motor comprising:

• a pair of coils commonly connected at an end thereof to one terminal of a source of potential;
• individual switch means connected to the opposite ends of each said coil and to the other terminal of said potential source;
• a diode in parallel with each said switch means and connected between said coil and said other terminal of said potential source and inversely poled with respect to current flow in said switch means;
• and
• an auxiliary diode connected between the commonly connected ends of said coils and said other terminal of potential source.

A coil circuit for a stepping motor comprising:

• a switching means connected to one terminal of a source of potential;
• first and second coil portions having therebetween a first current control means with said first and second coil portions and said current control means connected serially between the other terminal of said source of potential and said switching means;
• and
• a pair of supplemental current control devices each connected in parallel with a respective coil portion and said first current control device whereby the current in each said coil portion can be controlled to operate said coil portions individually, serially or in parallel.