Robotics Week1 coursera 1 Exam Questions
and Answers
Question 2
Consider a mechanism consisting of three spatial rigid bodies (including ground,
N=4) and four joints: one revolute, one prismatic, one universal, and one spherical.
According to Grubler's formula, how many degrees of freedom does the mechanism
have? - Answer-1(In Grubler's formula, N=4,m=6,J=4, and the sum of joint freedoms
is 1+1+2+3=71+1+2+3=7, giving 6(4−4−1)+7=16(4−4−1)+7=1 dof.
A mechanism that is incapable of motion has zero degrees of freedom. In some
circumstances, Grubler's formula indicates that the number of degrees of freedom of
a mechanism is negative. How should that result be interpreted? - Answer-The
constraints implied by the joints must not be independent.
Using the methods for determining the number of degrees of freedom of a rigid body
in 3-dimensional space from the book and the video, find the number of degrees of
freedom of a rigid body in a conceptual 4-dimensional space. Your answer should be
an integer. - Answer-10
Question 2
Referring back to Question 1, indicate how many of the total degrees of freedom are
angular (rotational). Your answer should be an integer. - Answer-6
Question 3
Assume your arm, from your shoulder to your palm, has 7 degrees of freedom. You
are carrying a tray like a waiter, and you must keep the tray horizontal to avoid
spilling drinks on the tray. How many degrees of freedom does your arm have while
satisfying the constraint that the tray stays horizontal? Your answer should be an
integer. - Answer-5
Question 4
Four identical SRS arms are grasping a common object as shown below.
Find the number of degrees of freedom of this system while the grippers hold the
object rigidly (no relative motion between the object and the last links of the SRS
arms). Your answer should be an integer. - Answer-10
Question 5
Referring back to Question 4, suppose there are now a total of n such arms grasping
the object. What is the number of degrees of freedom of this system? Your answer
should be a mathematical expression including n. Examples of mathematical
expressions including n are 4∗n−7 or n/3. - Answer-6+n
Referring back to Question 4 and 5, suppose the revolute joint in each of the n arms
is now replaced by a universal joint. What is the number of degrees of freedom of the
overall system? Your answer should be a mathematical expression including n.
Examples of mathematical expressions including n are 4∗n−7 or n/3. - Answer-2n+6
and Answers
Question 2
Consider a mechanism consisting of three spatial rigid bodies (including ground,
N=4) and four joints: one revolute, one prismatic, one universal, and one spherical.
According to Grubler's formula, how many degrees of freedom does the mechanism
have? - Answer-1(In Grubler's formula, N=4,m=6,J=4, and the sum of joint freedoms
is 1+1+2+3=71+1+2+3=7, giving 6(4−4−1)+7=16(4−4−1)+7=1 dof.
A mechanism that is incapable of motion has zero degrees of freedom. In some
circumstances, Grubler's formula indicates that the number of degrees of freedom of
a mechanism is negative. How should that result be interpreted? - Answer-The
constraints implied by the joints must not be independent.
Using the methods for determining the number of degrees of freedom of a rigid body
in 3-dimensional space from the book and the video, find the number of degrees of
freedom of a rigid body in a conceptual 4-dimensional space. Your answer should be
an integer. - Answer-10
Question 2
Referring back to Question 1, indicate how many of the total degrees of freedom are
angular (rotational). Your answer should be an integer. - Answer-6
Question 3
Assume your arm, from your shoulder to your palm, has 7 degrees of freedom. You
are carrying a tray like a waiter, and you must keep the tray horizontal to avoid
spilling drinks on the tray. How many degrees of freedom does your arm have while
satisfying the constraint that the tray stays horizontal? Your answer should be an
integer. - Answer-5
Question 4
Four identical SRS arms are grasping a common object as shown below.
Find the number of degrees of freedom of this system while the grippers hold the
object rigidly (no relative motion between the object and the last links of the SRS
arms). Your answer should be an integer. - Answer-10
Question 5
Referring back to Question 4, suppose there are now a total of n such arms grasping
the object. What is the number of degrees of freedom of this system? Your answer
should be a mathematical expression including n. Examples of mathematical
expressions including n are 4∗n−7 or n/3. - Answer-6+n
Referring back to Question 4 and 5, suppose the revolute joint in each of the n arms
is now replaced by a universal joint. What is the number of degrees of freedom of the
overall system? Your answer should be a mathematical expression including n.
Examples of mathematical expressions including n are 4∗n−7 or n/3. - Answer-2n+6
