Small deadband servocontrol system

A circuit for controlling the position of the rotor member of a reversible motor, which comprises:

• (a) control means comprised of first and second switchable means for selectively controlling the application and polarity of electrical power to said motor to cause rotational movement of said rotor member in a desired direction;
• (b) means responsive to the position of said rotor member for generating a position feedback signal indicative of the actual position of said rotor member;
• (c) means for generating a command position signal indicative of a desired position of said rotor member;
• (d) means responsive to said command position signal and to said position feedback signal for generating a position error signal indicative of the relative difference between the actual position and the desired position of said rotor member;
• (e) voltage divider means for generating a plurality of reference voltages;
• and
• (f) first and second comparator means coupled to said control means for comparing the voltage magnitude of said position error signal to the voltage magnitude of respective reference voltages and generating control signals to said switchable means to effect rotation of said rotor in a desired direction until the difference between the magnitudes of the respective reference voltage and the error signal falls within a predetermined dead-band voltage range.

A circuit for controlling the position of a motor driven member, comprising:

• a reversible motor drivingly connected to the driven member;
• first means, for selectively applying electrical power to the motor;
• second means, for generating an input signal corresponding to the difference between the desired position and the actual position of the driven member;
• third means, for generating first and second reference potentials, the first reference potential being of a higher voltage than the second reference potential;
• fourth means, for comparing the input signal with the first and second reference potentials and for applying a first signal to the first means upon the input signal being of higher potential than the first reference potential to drive the motor in one direction and for applying a second signal to the first means upon the input signal being of lower potential than the second reference potential to drive the motor in the opposite direction.