Abstract: An actuator system has a motor and an output shaft connected to a potentiometer that provides shaft position information. The motor and potentiometer are electrically connected to a common power supply. A microcomputer controls the application of power to the motor and potentiometer so that feedback signals from the potentiometer, indicative of shaft position, can be read when desired without moving the shaft. The motor is prevented from moving either by setting both motor terminals high during a read, or by applying power pulses during a read which are too short in duration to allow the motor to start moving.

Abstract: An apparatus and method for controlling brushless DC motors are provided. Velocity loop control is performed digitally to produce current commands at a high frequency loop closure interval. Commutation of field coil current is controlled in response to current commutation pattern control signals produced in response to measured relative position of the motor rotor and motor stator and a velocity average over a number of loop closure intervals. Switch control signals to control transistor switches providing current from a DC power source to the motor terminals are produced in response to the current commands, measured motor current and the commutation pattern control signals. The velocity loop control implements a selected transfer function relating velocity, the motor torque constant, and the moment of inertia of the motor and associated load. Facilities are provided for periodically adjusting velocity loop transfer function gain factors and the effective moment of inertia in response to input signals.

Abstract: A device for preventing a coil of a brushless motor from burning is disclosed.

Abstract: A burn-out preventive circuit for a commutatorless motor comprises drive windings of two phases, driving power transistors connected in series with the drive windings respectively, a position detecting element detecting the angular position of rotation of a permanent magnet rotor for alternately turning on the driving power transistors, and a protective circuit detecting a counter-electromotive force induced in the drive windings during rotation of the permanent magnet rotor for interrupting energization of the drive windings when the detected counter-electromotive force is lower than a predetermined level or zero.