The ? motor is a position or motion correcting motor that is driven to a specific angular position as commanded by a control signal.

• A. Stepper
• B. Servo
• C. Synchronous
• D. Induction

Answer: (B)

Servo control uses a feedback loop to move a motor to a commanded angular position and continuously correct any error between the target and the actual position. The control signal specifies the desired angle, and sensors like encoders provide position feedback to the drive, which adjusts the motor output to minimize the error. This closed-loop setup lets the system precisely reach and hold the commanded position even if load or friction changes.

Stepper motors can reach a chosen position by stepping, but they often operate without feedback, so they don’t inherently correct position errors in real time unless a closed-loop system is added. Induction and synchronous motors are typically used for speed or torque control and don’t provide the built-in position-correction behavior of a servo system unless paired with additional sensors and control.