NPTEL Advanced Robotics Week 8 Assignment Answers 2025
1. A stepper motor is normally not very accurate as it is operated in
- closed loop
- open loop
- uncertain environment only
- variable loading conditions only
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2. The main difference between a brush type DC motor and a Brushless DC motor is that
- rotor of a Brushless DC motor is made of thin magnets
- rotor of a brush type DC motor is made of thin magnets
- a brush type DC motor implements commutation through a software
- Brushless DC motor has mechanical commutator
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3. A disadvantage of a brush type DC motor is that
- there are permanent magnets in the rotor which is difficult to manufac-ture
- it is slightly more expensive as compared to Brushless DC motor
- its rotor is light and hence difficult to control
- its brushes wear out
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4. In an ultrasonic motor the stator has teeth made of
- piezoelectric material
- non-conductive material
- conductive material
- soft material
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5. The dynamics of a robotic manipulator acts on the control system as a
- random noise
- feedback term
- feed forward term
- disturbance
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6. In a PD controller, the values of the gains are chosen such that the system is
- over damped
- under damped
- critically damped
- heavily damped
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7. In a position regulator problem, m = b = k = 1. For kp = 8, the system is
critically damped. What is the corresponding value of kv ?
- 3
- 4
- 5
- 6
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8. For the control of a unit mass system using a PD controller, the value of
kp = 25. Find kv for it to be critically damped.
- 1
- 2
- 5
- 10
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9. When a robot picks up or drops an object, the change/effect in the link
inertia is minimal because
- it is divided by gear ratio
- it is divided by square of gear ratio
- it is multiplied by gear ratio
- it is multiplied by square of gear ratio
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10. If a system returns to the origin when subjected to disturbance then the system is
- unstable
- asymptotically unstable
- asymptotically stable
- none of the above
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