CS Theory Surprise Quiz - I

Identify the factor that is not essential for a practical control system.

• Stability

• Accuracy

• Sensitivity

• Sustained oscillation

Consider a fan to which an electric current is provided as input and the rotational speed of its shaft is the output. Indicate the solving method, if one wants to find the rotational speed corresponding to a given current.

• synthesis

• prediction

• control

• modelling

Recall the best example of closed loop control.

• Bread toaster

• Electric hand drier

• Car cruise control system

• Ceiling fan

In a typical closed loop system, Identify the element that calculates the control input based on the error between the reference input and the actual output.

• plant

• controller

• actuator

• sensor

Select the Laplace transform of e−3tsin(2t) in the following.

Consider the LTI system whose governing equation is y¨(t)+7y˙(t)+10y(t)=u(t).Take the initial conditions to be zero and let a unit step input be provided to this system. Select the value of the output as time tends to infinity.

• 0.1

• -0.5

• 0.33

• infinity

Relate the transfer function of a second-order system which is governed by y′′(t)+2y′(t)=u(t).

The signal flow graph for a system is given below Figure 1. Identify the transfer function Y(s)/U(s) for this system.

The block diagram of a feedback control system is shown in the Figure 2. Indicate the overall closed-loop gain G of the system.

In an automatic cruise control system of a car, the transfer function of the controller is combined in cascade with the vehicle dynamics. Infer the combination.

• Open-loop gain

• Forward path transfer function

• Feedback element

• Error detector