Control Systems Mcqs


How many types of controllers and compensators are there respectively?

A) 4, 3 B) 3, 4
C) 4, 5 D) 5, 4
Answer & Explanation Answer: A) 4, 3

Explanation: There are 4 types of controllers namely PID, PI, PD. There are 3 types of compensators namely Lag, Lead & Lag-Lead compensators.

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What is the need for a controller?

A) Receive control signals B) Transmit control signals
C) Modify control signals D) Create control signals
Answer & Explanation Answer: C) Modify control signals

Explanation: Controller is needed to modify control signals for better control action. Some control signals are raw signals which canít function properly so we use controllers for modifying them.

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Actuator is the basic component of an automatic control system.

A) False B) True
Answer & Explanation Answer: B) True

Explanation: There are 5 basic components of an automatic control system. They are error detector, amplifier, actuator, plant, and sensor. So, Actuator is a basic component of automatic control system.

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For a unity feedback control system, the open loop transfer function G(s) = 10(s+2)/s≤(s+1). What is the acceleration error constant?

A) Infinity B) 5
C) 10 D) 20
Answer & Explanation Answer: D) 20

Explanation: As limit s tends to zero s≤ G(s) H(s) = s2 G(s) = 10*2/1 = 20. Therefore we get the value of Ka as 20 and both kv and ks are infinity.

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A performance index must offer selectivity.

A) True B) False
Answer & Explanation Answer: A) True

Explanation: It must offer selectivity, that is, an optimal adjustment of parameters must clearly distinguish non optimal adjustment of parameters. If there was no selectivity we would not have been able to distinguish between parameters.

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The open loop transfer function for a unit feedback system is G(s) = K/s(sT+1). By what factor the amplitude gain K should be reduced so that the peak overshoot becomes 25% from 75%?

A) 75 B) 25
C) 20 D) 10
Answer & Explanation Answer: C) 20

Explanation: The peak overshoot is decreased by increasing the damping ratio. The damping ratio is increased by reducing the gain K by same proportion and for decreasing the peak overshoot from 75% to 25% the factor of amplitude becomes 19.6% which is approximately 20%.

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What is the analogous electrical element of Frictional coefficient (B) in Force-Current Analogy for mechanical translational system?

A) Resistance B) Conductance
C) Flux D) Voltage
Answer & Explanation Answer: B) Conductance

Explanation: As Resistance is the analogous element of B in F-V analogy so here it is the reciprocal of resistance, conductance is the answer. Force voltage analogy means both the equations will have differential equation of the same form.

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A unity feedback system has an open loop transfer function G(s) =25/s(s+8). What is the percentage of itís peak overshoot?

A) 0.13% B) 1.13%
C) 1.26% D) 1.52%
Answer & Explanation Answer: D) 1.52%

Explanation: Damping ratio is calculated from the characteristic equation and placing that value in the formula for peak overshoot Mp = e3.14DR (1- DR2) we get the answer. Peak overshoot arises especially in the step response of the systems such as low pass filters which are band limited.

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