GATE-CH-2003-79-ctrl-2mark

In the case of a feed-forward control scheme, which of the following is NOT true? 

1. It is insensitive to modeling errors
2. Cannot cope with unmeasured disturbances
3. It waits until the effect of the disturbance has been felt by the system before control action is taken
4. Requires good knowledge of the process model
5. Requires identification of all possible disturbances and their direct measurement

• 1 and 3

• 1 and 4

• 2 and 5

• 3 and 4

GATE-CH-2005-11-ctrl-1mark

Cascade control comes under the control configuration which uses

• one measurement and one manipulated variable

• more than one measurement and one manipulated variable

• one measurement and more than one manipulated variable

• more than one measurement and more than one manipulated variable

GATE-CH-2007-62-ctrl-2mark

Consider the following instrumentation diagram for a chemical reactor. \(C_{SP}\) represents a concentration setpoint.

Match the items in column A with the corresponding items given in column B.

Column A	Column B
P) control strategy	1) feed forward control
Q) primary control variable	2) cascade control
R) slowest controller	3) concentration in the reactor
S) fastest controller	4) reactor temperature
	5) jacket temperature
	6) concentration controller
	7) reactor temperature controller
	8) jacket temperature controller
	9) flow controller
	10) selective control

• P-2, Q-3, R-6, S-9

• P-1, Q-4, R-8, S-7

• P-10, Q-7, R-9, S-6

• P-1, Q-8, R-5, S-9

GATE-CH-2004-81-ctrl-2mark

The process and disturbance transfer functions for a system are given by

\( \begin{align*} G_p(s) &= \frac{\bar{y}(s)}{m(s)} = \frac{2}{(2s+1)(5s+1)} \\ G_d(s) &= \frac{\bar{y}(s)}{d(s)} = \frac{1}{(2s+1)(5s+1)} \end{align*} \)

The feed forward controller transfer function that will keep the process output constant for changes in disturbance is

• \(\dfrac{2}{(2s+1)^2(5s+1)^2}\)

• \(\dfrac{(2s+1)^2(5s+1)^2}{2}\)

• \(\dfrac{1}{2}\)

• \((2s+1)(5s+1)\)

GATE-CH-2014-46-ctrl-2mark

Given below is a simplified block diagram of a feedforward control system.

The transfer function of the process is \(G_p(s)=\dfrac{5}{s+1}\) and the disturbance transfer function is \(G_d(s)=\dfrac{1}{s^2+2s+1}\). The transfer function of the PERFECT feedforward controller, \(G_f(s)\) is

• \(\dfrac{-5}{(s+1)^3}\)

• \(\dfrac{-5}{(s+1)}\)

• \(\dfrac{-1}{5(s+1)}\)

• \(-5(s+1)\)

GATE-CH-2008-65-ctrl-2mark-DIFFER

Match the following:

• P-3, Q-2, R-4

• P-1, Q-2, R-3

• P-3, Q-4, R-2

• P-1, Q-4, R-2