All questions of Time response of discrete systems for Electrical Engineering (EE) Exam
Answer: d.
Explanation: The nature is dependent on system poles not on the dynamic inputs.
Given transfer function: G(s) = 100/(s+1)(s+100)
We need to find the approximate settling time for 2% criterion for a unit step input.
Step 1: Find the poles of the transfer function
The poles of the transfer function are located at s = -1 and s = -100.
Step 2: Find the dominant pole
The dominant pole is the pole that is closest to the imaginary axis. In this case, the pole at s = -1 is closer to the imaginary axis than the pole at s = -100. Therefore, the dominant pole is s = -1.
Step 3: Find the time constant
The time constant is the inverse of the real part of the dominant pole. In this case, the real part of the dominant pole is -1. Therefore, the time constant is 1/1 = 1 second.
Step 4: Find the settling time for 2% criterion
The settling time for 2% criterion is approximately equal to 4 times the time constant. Therefore, the settling time is:
Settling time = 4 x 1 = 4 seconds
Therefore, the approximate settling time for 2% criterion for a unit step input is 4 seconds.
Answer: Type = 2 which is the number of poles at the origin and order is the highest power of the characteristic equation.
Maximum peak overshoot is the normalized difference between the time response peak and steady state output.
Answer: c
Explanation: complex conjugate (non-multiple): oscillatory (sustained oscillations)
Complex conjugate (multiple): unstable (growing oscillations).
Differentiating the equation and getting the impulse response and then taking the inverse Laplace transform and converting the form into time constant form we get K = -7.5.
Answer: d
Explanation: Maximum overshoot, rise time and delay time are the major factor of the transient behaviour of the system and determines the transient characteristics.
Answer: d
Explanation: C(s)/R(s) = s/(s2+3s+2)
C(s) = 1/s-2/s+1+1/s+2
c(t) = 1-2e-t+e+2t.
Overshoot and undershoot are calculated from the formula of peak time as odd peaks denote the overshoot and even denotes the under shoot.
Answer: c
Explanation: Large overshoot refers to the maximum peak in the response of the closed loop system and this is mainly due to the high positive correcting torque.
Answer: a
Explanation: For analyzing transient response mainly step is used and also other signals mainly ramp and parabolic are not used for this analysis but they are used for steady state analysis.
Output response so calculated is the inverse Laplace transform of the input and impulse response and hence converting the resultant form in the time constant form time constant can be directly determined.CORRECT OPTION IS (A).
Answer: c
Explanation: Laplace response of impulse signal is one which implies Laplace response is systems response.
Answer: d
Explanation: Using final and initial values theorem directly to find initial and final values but keeping in mind that final value theorem is applicable for stable systems only.
Answer: b
Explanation: Practically there are some non-linearity present in the system as friction but in mathematical model these are considered by considering high gain and lower damping.
Answer: c
Explanation: C(s)/R(s) = 1/s2+s+1
C(s)/R(s) = w/ws2+2Gws+w2
Compare both the equations,
w = 1 rad/sec
2Gw = 1
Mp = 16.3 %
Answer: d.
Explanation: Impulse response of a system is the inverse Laplace transfer function of its Laplace function.
Answer: b
Explanation: G = 1/√2
Gw = 5
s = -5+j5.
Answer: d
Explanation: C(s) = 1/s-1/s+5-5/(s+5)^2
C(s) = 25/s(s2+10s+25)
R(s) = 1/s
G(s) = 25/(s2+10s+25 )
w= √25
w = 5 rad/sec
G = 1.
Answer: a
Explanation: Feedback’s inherent capability is that its parameter can be adjusted to alter both transient and steady state responses as together they are referred to as time responses.
Answer: c
Explanation: s+6/K[s2+s/K+6/K] Comparing with s2+2Gw+w2
w= √6/K
2Gw=1/K
2*0.5*√6/K =1/K
K=1/6.
Answer: b
Explanation: If response due to one standard signal is known then response due to other signals can also be derived.
Answer: d
Explanation: First order system is defined by total number of poles and also which is same as the order of differential equation.
Answer: d
Explanation: System dynamic behavior for analysis and design is therefore judged and compared under standard test signals.
Answer: a
Explanation: Natural frequency and damping can be designed by changing the gain of the individual system.
Answer: b
Explanation: Speed of response is the speed at which the response takes the final value and this is determined by damping factor which reduces the oscillations and peak overshoot as the peak is less then the speed of response will be more.
Answer: d
Explanation: Comparing the characteristic equation with the standard equation the value of the damping factor is calculated and the value for the option d is minimum hence the system will have the maximum overshoot .
Answer: d
Explanation: Step signal is the signal whose value varies from zero to level in zero time.
Answer: c
Explanation: C(s)/R(s) = 1/s2+s+1
C(s)/R(s) = w/ws2+2Gws+w2
Compare both the equations,
w = 1 rad/sec
2Gw = 1
Mp = 16.3 %
Answer: b
Explanation: The characteristic equation is considered and the values of G and w are calculated and further the value of k can be calculated.
Answer: a
Explanation: The transfer function of the controller is 0.1s+1/s
Gc(s) = 0.1s+1/s.
Answer: d
Explanation: C(s) = 1/s-1/s+5-5/(s+5)^2
C(s) = 25/s(s2+10s+25)
R(s) = 1/s
G(s) = 25/(s2+10s+25 )
w= √25
w = 5 rad/sec
G = 1.
Answer: b
Explanation: Comparing the equation with the characteristic equation and then finding the value of G and w and calculating the value of settling time as 4 sec from 4/Gw.
Answer: c
Explanation: The output is given as a function of time. The final value of the output is limn->∞c(t)=1; . Hence Td (at 50% of the final value) is the solution of 0.5=1-e-Td, and is equal to ln 2 or 0.693 sec.
Transient response analysis is the most general method for computing forced dynamic response. The purpose of a transient response analysis is to determine the behavior of a structure subjected to time-varying excitation. The transient excitation is explicitly defined in the time domain.
Answer: c
Explanation: s+6/K[s2+s/K+6/K] Comparing with s2+2Gw+w2
w= √6/K
2Gw=1/K
2*0.5*√6/K =1/K
K=1/6.
Answer: d
Explanation: Standard test signals are impulse, ramp and unit step all of the above to test the dynamic behavior of the control system.
In first order systems the time response during steady state the output velocity matches.
Answer: c
Explanation: Applying initial value theorem which state that the initial value of the system is at time t =0 and this is used to find the value of K and final value theorem to find the value of a.
Answer: c
Explanation: Ramp signal denotes constant velocity and also basic definition states that its value increases linearly with time.
Answer: c
Explanation: The response of a first order system is:
A(t)=a[1-e^-t/T] ½= 1-e^-10/t
T= 14.43 sec.
Answer: a
Explanation: Rise time, peak time, settling time and maximum peak overshoot are the prime factors of the time domain analysis and they must be specified in a consistent manner but they are mutually dependent.
Answer: d
Explanation: a(t)= k[1-e^-t/T] K=2
0.632= 1-e^-10/T
T=600 sec
G(s)=2/(1+600s).
The impulse response of a system can provide valuable information about its behavior and stability. In this case, we are given that the system has a complex conjugate root pair of multiplicity two or more in its characteristic equation. Let's analyze the implications of this on the system's impulse response.
Complex Conjugate Root Pair
A complex conjugate root pair in the characteristic equation of a system indicates the presence of oscillatory behavior in the system's response. Complex conjugate roots are of the form a ± bi, where a and b are real numbers and i is the imaginary unit (√-1). These roots give rise to sinusoidal terms in the impulse response.
Multiplicity Two or More
The multiplicity of a root refers to the number of times it appears in the characteristic equation. When a complex conjugate root has a multiplicity of two or more, it means that it appears multiple times in the equation. This results in an exponential rise or decay in the sinusoidal terms of the impulse response.
Implications on the Impulse Response
Based on the given information, the impulse response of the system will exhibit the following characteristics:
1. Sinusoidal Oscillation: The presence of a complex conjugate root pair indicates the occurrence of sinusoidal terms in the impulse response. These sinusoids represent the oscillatory behavior of the system.
2. Exponential Rise: Since the complex conjugate root pair has a multiplicity of two or more, the sinusoidal terms in the impulse response will experience exponential rise. This means that the amplitude of the oscillation will increase over time.
3. Unstable System: An exponentially rising sinusoidal term indicates an unstable system. As the amplitude continuously grows, the system's response becomes unbounded and uncontrollable. This behavior is undesirable in most engineering applications.
Conclusion
In summary, a system with a complex conjugate root pair of multiplicity two or more in its characteristic equation will have an impulse response that exhibits a sinusoidal oscillation with exponential rise. This behavior indicates an unstable system, as the response grows without bound.
Normalization refers to the desired to the reference value and normalized response of the dynamic system refers to the characteristic feature of a response due to specific excitation irrespective of its amplitude.
Answer: a
Explanation: Undamped natural frequency is the frequency that has suffered damping and gets affected by the increase in the speed of response and decrease in sensitivity.
Answer: c
Explanation: The output is given as a function of time. The final value of the output is limn->∞c(t)=1; . Hence Td (at 50% of the final value) is the solution of 0.5=1-e-Td, and is equal to ln 2 or 0.693 sec.
Answer: c
Explanation:
hence due to this G lies between 0 and 1.
Answer: c
Explanation: C(s)/R(s) = 2/s+1
R(s) = 1/s (step input)
C(s) = 2/s(s+1)
c(t) = 2[1-e-t] 1.96 = 2[1-e-T] T= 4sec.
Answer: c
Explanation: C(s)/R(s) = 2/s+1
R(s) = 1/s (step input)
C(s) = 2/s(s+1)
c(t) = 2[1-e-t] 1.96 = 2[1-e-T] T= 4sec.