Abstract: In a motor control system for a DC motor, a modulation circuit provides a plurality of pulse width modulated signals to control the current applied to the motor. The motor is coupled to a current sensing resistor and a plurality of switches responsive to the pulse width modulated control signals. The output of the current sensing resistor is summed with an input current command to provide an error signal. A modulation circuit which includes a waveform generator generates a plurality of interposed triangular waves adjustably offset by a predetermined amount. The triangular waves are compared to the error signal to provide pulse width modulated control signals which cause a "dither" current to be applied to the motor when there is substantially no input command and currents having substantially decreasing form factors to be applied as the input command increases.

Abstract: An X-ray table base, an intermediate support mounted on the base for moving bidirectionally, and a carriage with a patient cradle on it mounted for moving bidirectionally on the support. There are individual servomotors for driving the support and cradle, respectively. Each servomotor drives an analog tachometer. The tachometer signals are compared with ramp signals. When, for example, the intermediate support nears the limit of its forward travel, its servo amplifier receives a decreasing ramp signal and the servo amplifier for the cradle motor receives a concurrent increasing ramp signal such that the support decelerates to zero velocity at a predetermined rate and the cradle accelerates to the previous constant velocity of the support at a rate that results in the cradle moving at a constant rate relative to the base.

Abstract: A braking system for a mobile medical diagnostic device having forward support wheels operatively associated with proportional electromechanical brakes and a single central steerable wheel assembly at the rear of the device. Means are provided for generating throttle command signals and actual velocity signals and for comparing the two and for applying current to the proportional brakes to a degree which is proportional to the difference in those two signals. When this difference exceeds a predetermined level, a motor brake is further actuated to augment the proportional braking system. Also included is a means for automatically reducing the throttle command signal in proportion to the degree that the steerable wheel assembly is turned from the straight-ahead position.

Abstract: A stepping motor is energized by a power supply that supplies charges of power with the number and duration of the charges being controlled according to the current operating conditions of the motor. The charges are supplied to a capacitor across which the motor is connected for energization with the voltage developed across the capacitor being the voltage supplied the motor.