Which component is used to measure rotation or position in many robots?

• A. Gyro for rotation.
• B. Distance sensor for rotation.
• C. Encoder for rotation/position sensing.
• D. Pressure sensor for rotation.

Answer: (C)

To measure rotation or position in many robots, you use an encoder. An encoder attaches to a rotating shaft and turns its motion into a stream of digital pulses. Each pulse corresponds to a small increment of rotation, so by counting pulses you can determine how far the shaft has turned and, with known resolution, the exact angle or position of a joint. There are incremental encoders, which track relative movement and speed, and absolute encoders, which give a specific position value even after power loss. This feedback is essential for precise, closed-loop control of robotic motion.

Gyros measure rotation rate or orientation changes, not stable position, and can drift over time. Distance sensors measure how far away something is, not how much a joint has rotated. Pressure sensors detect force in a fluid or gas, not rotational position.