What does a shaft encoder measure?

A shaft encoder is a device that measures the amount of rotation of a shaft, often in degrees or counts of rotation. It works by converting the rotational movement into an electrical signal that can be interpreted by a microcontroller or computer. This measurement is crucial for applications where precise control and feedback about the position of a motor or wheel is needed.

The correct answer highlights that shaft encoders track how far an axle has rotated, allowing robotics systems to know their position and, consequently, to perform tasks like navigating to specific locations or maintaining a desired orientation. This accurate tracking of rotational movement is fundamental in robotics, enabling the system to adjust its actions based on real-time data.

In contrast, the other options do not align with the primary function of a shaft encoder. For instance, measuring the temperature of the motor is not within the scope of a shaft encoder's capabilities, as it focuses on motion rather than thermal properties. Although shaft encoders can indirectly contribute to understanding the distance traveled by a robot through wheel rotations, they do not measure distance directly. The speed of the wheels can be inferred from the rotation data, but since speed captures both distance and time, it does not fully encapsulate the core function of measuring rotation itself.