Abstract: A stepper motor is accelerated and decelerated with a parabolic velocity profile to efficiently utilize the available torque of the motor. The times between pulses to obtain a parabolic velocity profile are determined by a microprocessor-based stepper motor controller from desired values of start/stop velocity, maximum velocity and time to reach maximum velocity. The required times are stored in a random access memory and are used to supply to the motor a pulse train which follows the parabolic velocity profile during acceleration and deceleration. The controller is easily programmable to accommodate different motor characteristics, different applications and different operating parameters.

Abstract: An amplifier system for energizing a d.c. motor from a power source in response to an error signal includes a bridge circuit including a first switching transistor pair for supplying a first current from the power source through the motor in one direction and a second switching transistor pair for supplying a second current from the power source through the motor in the opposite direction. A zero crossing detector determines the sign of the error signal and enables the first transistor pair when the error is positive and enables the second transistor pair when the error is negative. A current sensing resistor senses the first and second currents through the motor and provides a motor current signal representative thereof. An absolute value circuit provides an absolute value error signal representative of the magnitude of the error signal.