Test: Introduction to Control Systems - 1 - Electronics and Communication Engineering (ECE) MCQ

A closed-loop system is generally more stable, accurate, and complex than an open-loop system. The main difference between the two is that closed-loop systems use feedback to adjust their control actions based on the output, while open-loop systems don't.

Linear system obeys both reciprocity theorem and principle of maximum power transfer.

A step function is commonly used as a input signal in a control system because:

• If we go through first order system, here we calculate steady-state error by providing input function then we got zero steady-state error.
• Actually in step function, output follows input always that means steady error is minimum.

Step Function:

Correct answer is D. e^−4s

• In closed loop system there is the presence of a feedback path and this feedback path has connected from output of the system to the input of the system.
• The whole operation is controlled by the output of the system.

• The main difference between an open-loop system and a closed-loop system is that the closed-loop system has the ability to self-correct while the open-loop system doesn't.
• Consequently, closed-loop systems are often called feedback control systems while open-loop systems are also known as non-feedback controls.

Feedback refers to the comparison of the final output to the desired output at respective input so as to get an accurate and error-free results and in the system improves the transient response of the system.

• The control system which operates on the time basis is an open loop system. For example, in automatic control of traffic, the time for each lamp (red, yellow and green) is fixed.
• The operation of each lamp does not depends upon the density of the traffic but depends upon the fixed time. Hence, assertion is true.
• Reason is also true but, it is not the correct explanation of assertion.

Ramp function occurring at t = 0 is denoted by r(t) = tu(t).
Ramp function occurring at t - a will be denoted: 

- In open loop control systems, the control action is independent of the desired output signal.
- The system operates without feedback, meaning it doesn't compare the output with the desired value.
- Control actions are predefined and do not adjust based on output changes.
- This can lead to inaccuracies if the system or external conditions change.
- Open loop systems are typically simpler but less accurate compared to closed loop systems, where feedback adjusts the control action.