EVOLUTION OF SERVO DRIVES The word ‘‘servo’’ is a learned borrowing from Latin where it meant ‘‘slave.’’ Industrial servos had their real beginning during World War II. Some applications were in military gun control and steering control. The evolution of speed and positioning drives since the war is shown in Figure 1. Industrial servos can be classified in four different ways as follows: By use: Cranes and hoists Winders Steering Refrigeration Heating Combustion Machine tool feed and speed Process control Power Guidance By variables controlled: Force Copyright 2003 by Marcel Dekker, Inc. All Rights ReservedTension Level Speed Position Mixture Temperature and humidity.
