Definitions of Control

Most control systems employ negative feedback, but some employ positive feedback. Negative feedback is operating when disturbances to a system evoke compensatory changes tending to diminish the effects of the disturbances returning the system towards its normal state. Positive feedback, unlike negative feedback, is explosive, and variables rapidly achieve a maximum or a minimum state. Any control system's adjustability is limited, and each control system operates best only within a restricted range. Within any range of control a disturbance may exceed the limits within which the control system can compensate for the disturbance. Failure to correct a disturbance may exert a domino effect, spreading rapidly and if related control systems cannot compensate for the failed control system, death ensues.

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