Question

In servo-system, the device used for derivative feedback is known as:

(a) Synchro

(b) Servomotor

(c) Potentiometer

(d) Tacho generator

The question was posed to me in an interview for internship.

This question is from State Variables and Linear Discrete-Time Systems topic in section State Variable Analysis and Design of Control Systems

Answer 1

The correct answer is:

(d) Tacho generator

Explanation:

In a servo-system, the device used for derivative feedback is typically a tacho generator. A tacho generator measures the rate of change of the system's output (i.e., the speed or velocity), which is essentially the derivative of the position or output signal. This is used in derivative feedback to improve the system's response and stability.

• Synchro (a) is used for angle measurement and position feedback, but not specifically for derivative feedback.
• Servomotor (b) is the actuator in the servo system, providing motion based on control input, but it doesn't provide derivative feedback.
• Potentiometer (c) is used to measure position (typically providing a feedback signal for position control) but does not provide derivative feedback.

Thus, the correct device for derivative feedback in a servo-system is the tacho generator.