Abstract: A method of automatically maintaining a nominal property value of a material near a limiting value in the process of making the material. The method involves the steps of imparting to the material a property that varies about the nominal value, and measuring the varying property, the measured property having positive and negative excursions about the nominal value. Determination is then made of the amplitudes of the excursions, and the nominal value of the property is adjusted to a predetermined limiting value in response to the amplitude of the most recent excursion, i.e., the nominal value is adjusted toward or away from the predetermined limiting value in respective response to any decrease or increase in the amplitude of the most recent excursion relative to the amplitude of the excursion immediately preceding the most recent excursion.

Abstract: A control method and circuit providing smooth transition between two regulating modes involving two regulating parameters, one active and one inactive. The method comprises the steps of providing a reference signal and developing a signal representing the inactive parameter. The two signals are then compared to provide an inactive output signal that is indicative of any difference existing between them. Another signal is developed that represents the active parameter, and this signal is compared to the inactive output signal. The inactive output signal is then forced continuously to the value of the signal representing the active parameter when the values of the two signals are different. Change from the one parameter and mode to the other parameter and mode can now be made without a disturbing effect.

Abstract: Means and method for controlling the power delivered to the shaft of a DC motor when the field of the motor becomes saturated and prevents control of armature voltage by the field of the motor. The method involves the step of increasing the current in the armature by an amount corresponding to the decrease in the voltage of the armature caused by a decrease in the speed of the armature during saturation of the field. Increasing armature current is effective to maintain power output of the motor constant. If the speed of the armature increases after the occurrence of saturation, the voltage of the armature increases, such that the method includes the additional step of decreasing armature current in proportion to the increasing armature voltage to maintain constant power output of the motor.