What is a servo feedback device, and which two components are common examples?

What is a servo feedback device, and which two components are common examples?

• A. A device that stores energy for the hydraulic system; examples: accumulator and bladder
• B. A device that senses ambient temperature; examples: thermometer
• C. A device that provides position/speed feedback to the controller; examples: encoder and resolver
• D. A device that powers actuators; examples: motor drive

Answer: (C)

In a servo system, feedback devices are used to close the loop by sending information about the actual motion back to the controller so it can compare it with the commanded motion and adjust the drive accordingly. A servo feedback device specifically provides position or speed information to the controller, enabling precise, real-time control of movement. Two common examples are an encoder and a resolver. An encoder measures rotational position and generates digital pulses (or a digital count) proportional to angle, giving high-resolution feedback about where the axis is and how fast it’s moving. A resolver, on the other hand, provides angle information through analog signals (typically sine and cosine), which robustly indicate position and can also be processed to yield speed. These sensors are central to achieving accurate closed-loop control in motion systems. Other options describe devices that store energy, measure environmental conditions, or simply power actuators, none of which function as feedback sensors for position or speed in a servo loop.

In a servo system, feedback devices are used to close the loop by sending information about the actual motion back to the controller so it can compare it with the commanded motion and adjust the drive accordingly. A servo feedback device specifically provides position or speed information to the controller, enabling precise, real-time control of movement.

Two common examples are an encoder and a resolver. An encoder measures rotational position and generates digital pulses (or a digital count) proportional to angle, giving high-resolution feedback about where the axis is and how fast it’s moving. A resolver, on the other hand, provides angle information through analog signals (typically sine and cosine), which robustly indicate position and can also be processed to yield speed. These sensors are central to achieving accurate closed-loop control in motion systems.

Other options describe devices that store energy, measure environmental conditions, or simply power actuators, none of which function as feedback sensors for position or speed in a servo loop.