Drone Systems and Control Nptel Week 2 Answers
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Drone Systems and Control Nptel Week 2 Answers (July-Dec 2025)
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Question 1. Which of the following forces primarily enables a quadcopter to hover?
a) Lift
b) Drag
c) Thrust
d) Buoyancy
Question 2. In a quadcopter, yaw motion is achieved by:
a) Tilting the rotors
b) Changing the direction of all propellers
c) Varying the speeds of clockwise and counter-clockwise rotors
d) Changing the altitude
Question 3. Which of the following is the most dominant factor in multirotor energy consumption?
a) Horizontal speed
b) Altitude
c) Payload weight
d) Rotor blade color
Question 4. What happens to the lift when the RPM of a rotor increases?
a) Lift decreases linearly
b) Lift remains constant
c) Lift increases quadratically
d) Lift increases exponentially
Question 5. In the context of multirotor dynamics, the term “moment of inertia” primarily affects:
a) Translational motion
b) Altitude control
c) Rotational dynamics
d) Battery efficiency
These are Drone Systems and Control Nptel Week 2 Answers
Question 6. Which of the following statements is true about symmetric quadcopters?
a) All arms must be unequal in length
b) Opposing rotors rotate in the same direction
c) The torque produced by adjacent rotors is always equal and opposite
d) Pitch and roll are not independently controllable
Question 7. Which sensor is most commonly used for altitude estimation indoors (without GPS)?
a) Magnetometer
b) Barometer
c) Ultrasonic sensor
d) Gyroscope
Question 8. What does an IMU typically consist of?
a) GPS and camera
b) Accelerometer and gyroscope (and optionally magnetometer)
c) LiDAR and sonar
d) Radar and barometer
Question 9. GPS is primarily used in drones to provide:
a) Altitude measurement
b) Local obstacle detection
c) Global positioning and velocity
d) Airspeed measurement
Question 10. Which of the following sensors provides angular velocity?
a) Accelerometer
b) GPS
c) Gyroscope
d) Ultrasonic sensor
Question 11. What is the function of an optical flow sensor in drones?
a) Determine air pressure
b) Track position using visual cues
c) Control motor RPM
d) Measure wind speed
These are Drone Systems and Control Nptel Week 2 Answers
Question 12. Which of the following correctly expresses the relationship between Mean Squared Error (MSE), bias, and variance?
a) MSE = Bias² – Variance
b) MSE = Variance + Noise
c) MSE = Bias² + Variance
d) MSE = Bias + Variance²
Question 13. If an estimator has zero bias and low variance, then it is:
a) Accurate but not precise
b) Precise but not accurate
c) Both accurate and precise
d) Neither accurate nor precise
Question 14. An estimator consistently overestimates the true value. This estimator:
a) Has high variance
b) Has zero bias
c) Is unbiased but inconsistent
d) Has positive bias
These are Drone Systems and Control Nptel Week 2 Answers
Question 15. Suppose you have two estimators:
Estimator A has low bias and high variance
Estimator B has high bias and low variance
Which of the following is true?
a) Estimator A always has lower MSE than B
b) Estimator B is better in all cases
c) The better estimator depends on the balance of bias² and variance
d) Estimator A is unbiased, so it’s always preferred
Question 16. Two estimators have the following properties:
Estimator A: Bias = 1, Variance = 3
Estimator B: Bias = 0.5, Variance = 4
Which estimator has the lower MSE?
a) Estimator A
b) Estimator B
c) Both are equal
d) Cannot be determined
These are Drone Systems and Control Nptel Week 2 Answers
Question 17. A state estimator in drones helps in:
a) Visual tracking only
b) Combining sensor data to estimate position, orientation, and velocity
c) Filtering audio signals
d) Only tuning PID gains
Question 18. A quadrotor drone weighs 1.6 kg. Assume standard gravity g = 9.81 m/s², and each rotor provides equal thrust. What is the minimum thrust per rotor (in Newtons) required to hover?
a) 3.92 N
b) 9.81 N
c) 15.7 N
d) 19.62 N
Question 19. An ultrasonic sensor on a drone sends a sound pulse downward and receives the echo 12 milliseconds later. Assume the speed of sound in air is 343 m/s. What is the altitude of the drone?
a) 1.715 m
b) 2.058 m
c) 4.116 m
d) 2.400 m
Question 20. In a standard quadrotor configuration (X-type), how are the propellers arranged to maintain yaw stability and torque balance?
a) All four propellers spin in the same direction
b) All front propellers spin clockwise, rear spin counter-clockwise
c) Adjacent propellers spin in the same direction
d) Opposing pairs spin in opposite directions (two CW, two CCW)
These are Drone Systems and Control Nptel Week 2 Answers