A. In any open loop control system, the output is not compared with the reference input. B. Traffic control by means of signals operated on a time basis is an example of closed loop control. C. Closed loop control always implies the use of feedback control action in order to reduce system error. D. Washing machine is an example of open loop system. E. Stability is a major concern in open loop control system. Choose the correct answer from the options given below:
Control System Statements Analysis
This question requires evaluating the definitions and characteristics of open-loop and closed-loop control systems based on given statements.
Statement Evaluation
- Statement A: "In any open loop control system, the output is not compared with the reference input."
- Analysis: This is the fundamental definition of an open-loop system. The control action is independent of the system's output.
- Verdict: Correct
- Statement B: "Traffic control by means of signals operated on a time basis is an example of closed loop control."
- Analysis: Traffic signals operating on a fixed timer without sensing traffic flow are open-loop systems. They do not use feedback to adjust signal timing based on the output (traffic congestion).
- Verdict: Incorrect
- Statement C: "Closed loop control always implies the use of feedback control action in order to reduce system error."
- Analysis: Feedback is the core component of closed-loop systems, enabling comparison between the desired output (reference input) and the actual output to calculate and minimize the error.
- Verdict: Correct
- Statement D: "Washing machine is an example of open loop system."
- Analysis: A standard washing machine operates on pre-set timings for different cycles (wash, rinse, spin) without measuring the cleanliness of clothes. This lack of output measurement and feedback makes it an open-loop system.
- Verdict: Correct
- Statement E: "Stability is a major concern in open loop control system."
- Analysis: Stability is primarily a critical concern in closed-loop systems, where feedback can potentially lead to oscillations or instability. Open-loop systems are generally stable unless their components have inherent instability issues.
- Verdict: Incorrect
Conclusion
Based on the analysis, statements A, C, and D are correct. Therefore, the option including only these statements is the correct answer.
Important Questions from Basics of Control Systems
- Match the LIST-I with LIST-IIChoose the correct answer from the options given below:
LIST-I LIST-II A. Nyquist Criterion I. Polar Plots B. Bode Plot II. Rectangular Plots C. Phase Margin III. Amount of additional phase lag at the gain crossover frequency required to bring the system to the verge of instability D. Gain Margin IV. It is the reciprocal of the magnitude $|G(j\omega)|$ at the frequency at which the phase angle is $-180^\circ$. - Which of the following statement is not correct in respect of Transfer Function of linear Time Invariant System
Read the following statements about the transfer function of a system :
(a) The transfer function provides complete insight into the structure of the system.
(b) It offers a symbolic picture about the dynamic characteristics of the system.
(c) It does not give any insight into the structure of the system.
(d) If the transfer functions of individual components of the system are known, the overall characteristics of the system can be determined just by taking their product.
Which of the above statements are correct ?
The mass-spring-damper system shown in the following figure represents :
The error detector element in a control system gives
