When the control device sends a signal to the actuator to move to a specific position, the actuator starts to move, and the feedback device signals back to the controller where and how fast the actuator is moving. The controller then reviews the feedback and determines if the motor has reached the commanded position. If not, the control device will continue to signal the actuator to move until it receives a signal from the feedback device that the motor has reached the desired position.
The servo system operates much like the processes of the human body – a remarkable multi axis motion system of hundreds of muscles, multiple feedback devices, and a control system that makes swift adjustments. As an example, a baseball player steps up to the plate to bat and the brain analyzes the current situation, the number of players on base, the current number of outs, the position of the defense. The batter glances toward the third base coach and receives the signal to hit the ball (the image passes from the eyes to the brain). As the pitcher throws the ball, the batter anticipates the pitch, and contemplates where the ball will cross the plate. As the pitcher releases the ball, the batter’s eyes send information to the brain, the brain analyzes the ball’s flight, makes split second decisions, sends signals to multiple muscles, and coordinates the swing of the bat to precisely hit the ball. If the batter misses the ball, the brain analyzes the error to adjust for the next pitch. The human body, like a servo system, works in a coordinated dance of precision motion. The modern industrial servo system has advanced significantly and now includes complex controllers with multiple feedback devices and fast processors that make nanosecond decisions to perform the desired motion. A breakdown of a typical industrial servo system includes:
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