# Robotics MCQ – Set 2

This set of Multiple Choice Questions & Answers (MCQs) focuses on “Robotics – Set 2”.

1. The __________ of a manipulator is a measure of how close the manipulator can come to a given point within its workspace.
a) Accuracy
b) Repeatability
c) Efficiency
d) Resolution

Explanation: According to the definition, accuracy is the term used to measure how close the manipulator can come to a specified point within its workspace. Accuracy is aﬀected therefore by computational errors, machining accuracy in the construction of the manipulator, ﬂexibility eﬀects such as the bending of the links under gravitational and other loads, gear backlash, and a host of other static and dynamic eﬀects.

2. Which manipulator is also called as an anthropomorphic manipulator?
a) Articulated manipulator (RRR)
b) Cartesian manipulator (PPP)
c) SCARA manipulator (RRP)
d) Cylindrical manipulator (RPP)

Explanation: Another name for articulated manipulator is revolute, or anthropomorphic manipulator. The revolute conﬁguration provides for relatively large freedom of movement in a compact space.

3. Repeatability is a measure of how close a manipulator can return to a previously taught point.
a) False
b) True

Explanation: According to the definition, repeatability is a measure of how close a manipulator can return to a previously taught point. Once a point is taught to the manipulator, however, say with a teach pendant, the above eﬀects are taken into account and the proper encoder values necessary to return to the given points are stored by the controlling computer. Repeatability therefore is aﬀected primarily by the controller resolution.

4. Controller ___________ is the smallest increment of motion that the controller can sense.
a) Accuracy
b) Repeatability
c) Efficiency
d) Resolution

Explanation: Controller resolution is the smallest increment of motion that the controller can sense. The resolution is computed as the total distance traveled by the tip divided by 2n, where n is the number of bits of encoder accuracy.

5. Manipulators that are highly repeatable are very accurate.
a) False
b) True

Explanation: Repeatability and accuracy of manipulators are not proportional, since accuracy of a manipulator is a measure of how close the manipulator can come to a given point within its workspace and repeatability is a measure of how close a manipulator can return to a previously taught point. Most present day manipulators are highly repeatable but not very accurate.

6. Generally, which type of robots have higher accuracy?
a) Non-rigid
b) Rigid
c) Smaller
d) Larger

Explanation: Accuracy is aﬀected by construction of the manipulator and ﬂexibility eﬀects. It is primarily for this reason that robots are designed with extremely high rigidity. Without high rigidity, accuracy can only be improved by some sort of direct sensing of the end-eﬀector position. The size of the robot doesn’t really affect the accuracy.

7. Prismatic joints typically have higher resolution than revolute joints.
a) False
b) True

Explanation: The resolution is computed as the total distance traveled by the tip divided by 2^n, where n is the number of bits of encoder accuracy. Prismatic joints, typically have higher resolution than revolute joints, since the straight line distance traversed by the tip of a linear axis between two points is less than the corresponding arc length traced by the tip of a rotational link.

8. Name the manipulator in which the links form a closed chain.
a) Parallel
b) Articulated
c) Cartesian
d) Gantry-box type

Explanation: A parallel manipulator is one in which the links form a closed chain. More speciﬁcally, a parallel manipulator has two or more independent kinematic chains connecting the base to the end-eﬀector.

9. If a system has 4 number of bits of encoder accuracy and the total distance traveled by the tip is L, then what is the controller resolution?
a) L/4
b) L/8
c) L/16
d) L/32

Explanation: The resolution is computed as the total distance traveled by the tip divided by 2n, where n is the number of bits of encoder accuracy. So here, n=4 and total distance traveled by the tip is L, so resolution = L/(24) = L/16.

10. The closed chain kinematics of parallel robots can result in greater ___________, than open chain robots.
a) Accuracy
b) Flexibity
c) Resolution
d) Repeatability

Explanation: The closed chain kinematics of parallel robots can result in greater structural rigidity. Since they have greater rigidity, hence they will have greater accuracy than open chain robots.

Sanfoundry Global Education & Learning Series – Robotics.

To practice all areas of Robotics, here is complete set of Multiple Choice Questions and Answers.

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