A Servo-Controlled Device or system is one that uses a servo mechanism to achieve precise and accurate control over position, speed, or other parameters. At its core, a servo mechanism is a closed-loop system that continuously monitors the output and compares it to the desired input. Any difference between the two, known as the error signal, is used to drive a motor, which in turn adjusts the system's output until the error is minimized. This feedback loop allows for high-precision adjustments and is the key to a servo-controlled system's effectiveness. This technology is widely used in applications ranging from robotics and automation to the voltage regulation in servo stabilizers, ensuring stable and reliable performance.