Questions without answers in Control Systems

Among the following, the differential equation(s) not representative of a linear dynamical system is/are $\_\_\_\_\_\_$.$\dfrac{d^{2} x}{d t^{2}}+2 t \dfrac{d x}{d t}+x(t...

A linear time invariant (LTI) system is described by:$$\begin{array}{c}{\left[\begin{array}{l}\dot{x}_{1} \\\dot{x}_{2}\end{array}\right]=\left[\begin{array}{cc}0 & 1 \\-...

A linear time invariant (LTI) system has a transfer function$$G(s)=\frac{10(s+1)}{s\left(s^{2}+2 s+5\right)}$$The system is placed in unity negative feedback configuratio...

The system $G(s)=\dfrac{K}{(s+1)^{4}}$ has a gain margin of $20$ dB. The value of $K$ is $\_\_\_\_$. (rounded off to two decimal places)

In the phase-locked-loop circuit shown below, the output of the VCO is a digital square wave.If the input is a square wave at $10$ $\mathrm{kHz}$, the steady state freque...

For the transfer function $G(s)=1+\frac{2 s-1}{s^{3}+5 s^{2}+3 s+22}$, the number of zeros lying in the left half of the $s$-plane is$0$$1$$2$$3$

Consider the control system block diagram given in Figure (a). The loop transfer function $G(s) \: H(s)$ does not have any pole on the $j \omega$-axis. The counterclockwi...

The figure shows a closed-loop system with a plant $G(s)=\frac{1}{s^{2}}$ and a lead compensator $C(s)$. The compensator is designed to place the dominant closed-loop pol...

The plant in the feedback control system shown in the figure is $P(s)=\frac{a}{s^{2}-b^{2}}$, where $a>0$ and $b>0$. The type(s) of controller $C(s)$ that CANNOT stabiliz...

A feedback control system is shown in the figure.The maximum allowable value of $n$ such that the output $y(t)$, due to any step disturbance signal $d(t)$, becomes zero a...

The pressure drop across a control valve is constant. The control valve with inherent characteristic has decreasing sensitivity. If $x$ represents the fraction of maximum...

Consider the state-space representation of a system$$ \dot{x}=A x+B u $$where $x$ is the state vector, $u$ is the input, $A$ is the system matrix and $B$ is the input mat...

The sinusoidal transfer function corresponding to the polar plot shown in the figure, for $T>0$, is$1-j \omega T$$\dfrac{1-j \omega T}{1+j \omega T}$$1+j \omega T$$\dfrac...

​​​​Consider the feedback control system shown in the figure. The steady-state error $e_{s s}=\lim _{t \rightarrow \infty}(r(t)-y(t))$ due to unit step reference $r(t)$ i...

​​The transfer function of a system is$$G(s)=\frac{\omega_{n}^{2}}{s^{2}+2 \xi \omega_{n} s+\omega_{n}^{2}}$$Choose the range of $\xi$ and $\omega_{n}$ (in $\mathrm{rad} ...

Consider a unity negative feedback system with its open-loop pole-zero map as shown in the figure. If the point $s=j \alpha, \alpha>0$, lies on the root locus, the value ...

A system has the transfer-function$\frac{Y(s)}{X(s)}=\frac{s-\pi}{s+\pi}$Let $u(t)$ be the unit-step function. The input $x(t)$ that results in a steady-state output $y(t...

The number of zeros of the polynomial $P(s)=s^{3}+2 s^{2}+5 s+80$ in the right- half plane is_________.

The number of times the Nyquist plot of $G(s) H(s)=\frac{1}{2} \frac{(s-1)(s-2)}{(s+1)(s+2)}$ encircles the origin is_______________.

The magnitude and phase plots shown in the figure match with the transfer-function______________.$\frac{10000}{s^2+2 s+10000} $$ \frac{10000}{s^2+2 s+10000} e^{-0.05 s}$$...

Consider a standard negative feedback configuration with $G(s)=\frac{1}{(s-2)(s-3)}$ and the controller $C(s)=K_P+\frac{K_I}{s}+K_D s$. The root-locus of $G(s) C(s)$ is p...

The phase margin of the transfer function $G(s)=\frac{2(1-s)}{(1+s)^{2}}$ is____________degrees. (rounded off to the nearest integer).

A unity-gain negative-feedback control system has a loop-gain $L(s)$ given by$$L(s) = \frac{6}{s(s-5)}$$The closed-loop system is _________Causal and stableCausal and uns...

The transfer function of a system is:$$\frac{(s+1)(s+3)}{(s+5)(s+7)(s+9)}$$In the state-space representation of the system, the minimum number of state variables (in inte...

The signal flow graph of a system is shown. The expression for $Y(s)/X(s)$ is ___________ $\frac{2G_{1}(s) G_{2}(s) + 2G_{1}(s) G_{3}(s)} {1 + G_{2}(s) + G_{3}(s)}$$2 + G...

A proportional-integral-derivative $\text{(PID)}$ controller is employed to stably control a plant with transfer function$$P(s) = \frac{1}{(s+1)(s+2)}$$Now, the proportio...

The Nyquist plot of a stable open-loop system $G (j \omega)$ is plotted in the frequency range $0 \leq \omega < \infty$ as shown. It is found to intersect a unit circle w...

In a unity-gain feedback control system, the plant$$P(s) = \frac{0.001}{s(2s+1)(0.01s+1)}$$is controlled by a lag compensator$$C(s) = \frac{s+10}{s+0.1}$$The slope $(\tex...

Taking $\text{N}$ as positive for clockwise encirclement, otherwise negative, the number of encirclements $\text{N}$ of $(-1,0)$ in the Nyquist plot of $G\left ( s \right...

Consider a unity feedback configuration with a plant a $\text{PID}$ controller as shown in the figure. $G\left ( s \right )=\dfrac{1}{\left ( s+1 \right )\left ( s+3 \rig...

A sinusoid $\left ( \sqrt{2} \sin t \right ) \: \mu \left ( t \right )$, where $\mu \left ( t \right )$ is the step input, is applied to a system with transfer-function $...

Consider a system with transfer-function $G\left ( s \right )=\dfrac{2}{s+1}$. A unit step function $\mu \left ( t \right )$ is applied to the system, which results in an...

The loop transfer function of a negative feedback system is $G(s)H(s)=\frac{1}{s(s-2)}$. The Nyquist plot for the above system _________.encircles $(-1+j0)$ point once in...

The loop transfer function of a negative feedback system is given by $G(s)H(s)=\frac{K}{s(s+2)(s+6)}$, where $K>0$. The value of $K$ at the breakaway point of the root lo...

The system shown in Fig.(a) has a time response y(t) to an input $r(t)=10u(t)$ as shown in Fig. (b), $u(t)$ being the unit step input. Both $K, t$ are positive. The gain ...

Consider the following state variable equations:$\dot{x_1}(t)=x_2(t)$$\dot{x_2}(t)=-6x_1(t)-5x_2(t)$The initial conditions are $x_1(0)=0 \:and\: x_2(0)=1.$ At $t=1$ secon...

The loop transfer function of a negative feedback system is $ G(s)H(s)=\frac{2(s+1)}{s^2}$. The phase margin of the system $\text{(in degrees, rounded off to one decimal ...

A phase lead network has the transfer function $G(S)=\frac{1+0.2s}{1+0.05s}$. The angular frequency at which the maximum phase shift for the network occurs is ___________...

The closed loop transfer function of a control system is given by $\frac{C(s)}{R(s)}=\frac{1}{s+1}$. for the input $r(t)=\sin\;t$ the steady state response $c(t)$ is ____...

The block diagram of a closed-loop control system is shown in the figure. The values of $K$ and $K_p$ are such that the system has a damping ratio of $0.8$ and an undampe...