Difference between revisions of "Modern Robotics Errata"

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The errata below are for the [[Modern_Robotics|'''updated first edition of ''Modern Robotics'' ''']] (as well as the practice exercises and linear algebra refresher appendix). The updated first edition (also called "version 2") was originally published by Cambridge University Press in late 2019 (marked "3rd printing 2019" or later) and the corresponding online preprint is dated December 2019. The updated first edition includes several corrections and minor additions to the original first edition, which was originally published by Cambridge in May 2017, with a corresponding online preprint dated May 2017.
[https://docs.google.com/forms/d/1iZ_3LsWR1iuPJmRsUQsa2ehZj6p-qKQfx8NRKaTlIuE/edit '''Please click here to report any corrections for the book, practice exercises, or linear algebra refresher appendix. (Please make sure you are using the May 3, 2017, online version of the book, or the hardcover book published by Cambridge University Press.)''']


'''[[Modern Robotics Errata, First Edition Version 1|The errata for the original first edition can be found here]].'''
Errata below are for [[Modern_Robotics|the hardcover book published by Cambridge University Press, the preprint version of the book posted on May 3, 2017, the practice exercises, and the linear algebra refresher appendix]]. Thanks to everyone who provided corrections to earlier versions!


[https://docs.google.com/forms/d/1iZ_3LsWR1iuPJmRsUQsa2ehZj6p-qKQfx8NRKaTlIuE/edit '''Please click here to report any corrections for the updated first edition of the book, the practice exercises, or the linear algebra refresher appendix.''']


== Book: Significant corrections ==
== Book: Significant corrections ==

=== Chapter 2 ===

* Proposition 2.2 says that Grubler's formula "provides a lower bound on the number of degrees of freedom" of a mechanism to account for the case where the joint constraints are not independent. This statement is misleading, as it assumes a linear analysis of mobility. In fact, some mechanisms may have '''fewer''' dof than implied by Grubler's formula by a higher-order analysis. A more correct statement is that Grubler's formula yields the correct number of dof in the "generic" case (where the joint constraints are independent and a linear analysis of mobility suffices), but a mechanism may have more dof (e.g., if the joint constraints are not independent everywhere) or fewer dof (e.g., the zero-dof four-bar linkage where the sum of the lengths of three links equals the length of the fourth link). This comment also applies to the sentence immediately after Example 2.6, the fifth bullet of the Summary in Chapter 2.6, and the second-to-last sentence of the third paragraph of Chapter 1's summary of Chapter 2.


=== Chapter 3 ===
=== Chapter 3 ===


* (printed version only) At the end of the introduction Exercise 3.16, it says "origin of {b} is at (0,2,0) is {s}" but "is {s}" should be "in {s}".
* In the caption of Figure 3.3, it should read <math>\hat{\text{x}}_{\text{b}} = (1/2, \sqrt{3}/2)</math> and <math>\hat{\text{y}}_{\text{b}} = (-\sqrt{3}/2, 1/2)</math>.
* Exercise 3.20, Figure 3.26: In the figure, the y and z axes for the {a}, {b}, and {c} frames are switched (y should point forward and z should point up). Also, the space frame is located at the bottom of the small wheel, directly below the {a} frame.
* Under "Representing a configuration" in Chapter 3.3.1.2, the text says "<math>T_{bc} = (R_{bc},p_{bc})</math> represents {b} relative to {c}" but it should say "represents {c} relative to {b}".
* There is a typo in the final matrix, <math>T_{ce}</math>, of Example 3.19. The term <math>130/\sqrt{2}</math> should be <math>160/\sqrt{2}</math>. (Also, there is no need to use <math>T_{ad}</math> in this example.)
* (printed version only) Exercise 3.25(a): the element in the third row and third column of the matrix <math>A</math> should be 0 (it is incorrectly written as 1).'''
* In the displayed equation just after Equation (3.76), the left-hand side should be <math>[\mathcal{V}_s]</math> (the brackets are missing).
* Exercise 3.16(i) asks for "the <math>\{q,\hat{s},h\}</math> representation" but it should say "a <math>\{q,\hat{s},h\}</math> representation" since <math>q</math> is not unique.

=== Chapter 4 ===

* Example 4.1, last row of the table (screw axis for joint 3): The linear component <math>v_i</math> should be <math>(0, -L_2, 0)</math> (the <math>-</math> sign is missing).

=== Chapter 5 ===

* Equation (5.7): The first two terms on the right-hand side of the equation should be <math>J_{s1} \dot{\theta}_1 + J_{s2}(\theta) \dot{\theta}_2</math>.

* Exercise 5.2(b): The wrench applied by the last link, expressed in the {s} frame, is 5 N in the <math>\hat{\text{y}}_{\text{s}}</math> direction, with zeros in all other components. (The wording seems to imply that the force is through the tip of the last link, which is incorrect.)

* Exercise 5.16 and Figure 5.26: The robot is referred to as PRRRRR, but it is PRPRRR.

=== Chapter 6 ===

* Chapter 6.3, first line after Eq (6.7): the matrices <math>T_{sd}^{-1} \dot{T}_{sd}</math> and <math>\dot{T}_{sd} T_{sd}^{-1}</math> are referred to as twists, but these are the se(3) matrix representations of the twists.


=== Chapter 8 ===
=== Chapter 8 ===


* In Equation (8.14), <math>\mathcal{K}(\theta)</math> should be replaced by <math>\mathcal{K}(\theta,\dot{\theta})</math>.
* (printed version only) Equation (8.74): the first two plus signs should be minus signs.

* Figure 8.5 says the volume of the rectangular parallelepiped is <math>abc</math> but it should be <math>hlw</math>.

* End of first sentence after Eq (8.26) in Section 8.2.1 should read "columns of <math>R_{bc}</math> correspond to the eigenvectors of <math>\mathcal{I}_b</math>." (The word "eigenvalues" should be replaced by "eigenvectors.")

* Caption of Figure 8.10: The operating region is light gray and the continuous operating region is dark gray.

* Exercise 8.6(a): The expression <math>\text{ad}_{J_i}(J_j)</math> has the indices switched; the correct expression is <math>\text{ad}_{J_j}(J_i)</math>.

* Exercise 8.7: The expression should be written:
<math>
\dot{M} = -\mathcal{A}^{\rm T} \mathcal{L}^{\rm T} \mathcal{W}^{\rm T} [\mbox{ad}_{\mathcal{A} \dot{\theta}}]^{\rm T} \mathcal{L}^{\rm T} \mathcal{GLA} -
\mathcal{A}^{\rm T} \mathcal{L}^{\rm T} \mathcal{GL} [\mbox{ad}_{\mathcal{A} \dot{\theta}}] \mathcal{WLA}
</math>

=== Chapter 10 ===

* Equation (10.4) should read <math> u = F(q) - B \dot{q}</math> (the plus sign in the book should be a minus sign).

=== Chapter 11 ===

* In the displayed equation after Equation (11.18), the vector <math>X_e(t)</math> is a six-vector. The bottom three elements are written correctly, but the top three elements, an angular velocity, are written instead in their 3x3 <math>so(3)</math> form. Also, the term written <math>R^{\text{T}}(d)</math> should be written <math>R^{\text{T}}(t)</math>.

* In Equation (11.33), the right-hand side should be zero (<math>c = 0</math>).

* Figure 11.24, the Robonaut 2 series elastic actuator, 4th sentence of the caption: The words "outer" and "inner" should be switched, so the new sentence reads "The inner ring of hole mounts connects to the harmonic gearhead output, and the outer ring of hole mounts is the output of the SEA, connecting to the next link."

=== Chapter 12 ===

* In Example 12.4, the elements of the wrenches <math>\mathcal{F}_1, \mathcal{F}_2, \mathcal{F}_3</math> are erroneously written in the order <math>(f_x,f_y,m_z)</math>; they should be written in the order <math>(m_z,f_x,f_y)</math>, i.e., <math>(-2,0,1), (1,-1,0), (1,1,0)</math>, respectively.

=== Appendix C ===

* Section C.3, Equation (C.5): All instances of <math>\phi_{i-1}</math> should be replaced by <math>\phi_i</math>.

* In Equation (C.12), two instances of <math>M_{i-1}</math> should be replaced by <math>M_i</math>.


== Book: Minor typos, etc., no danger of misunderstanding ==
== Book: Minor typos, etc., no danger of misunderstanding ==


=== Chapter 1 ===
=== Throughout the book ===


* The V-REP simulator has been discontinued and replaced by the [https://www.coppeliarobotics.com/ CoppeliaSim] simulator. This does not change anything in the book (or the simulation scenes provided to accompany the book).
* (online version only) Description of Chapter 6: "jont positions" should be "joint positions."

=== Chapter 2 ===

* Chapter 2.2.2, Example 2.3: "Substituting" is misspelled.

=== Chapter 3 ===

* Near the end of Chapter 3.6 Software, the function "AxisAng" should be written "AxisAng6."

=== Chapter 5 ===

* Figure 5.15(b): The circular arrow indicating the rotation of joint 3 is slightly misplaced.

* Exercise 5.25: This problem instructs you to use the space Jacobian, so you should use it for the manipulability ellipsoids in this problem (even though it is generally preferred to use the body Jacobian for manipulability ellipsoids).


=== Chapter 6 ===
=== Chapter 6 ===


* (online version only) Figure 6.7: <math>\theta_0</math> should be <math>\theta^0</math> (five times) and <math>\theta_1</math> should be <math>\theta^1</math> (one time).
* (printed version only) Chapter 6.2.2, Example 6.1: just before the matrix <math>T_{sd}</math>, "corresponds to to" should be "corresponds to." '''
* (printed version only) Chapter 6.3, first sentence after Equation (6.7): "however small" should be written "however, small" to avoid ambiguity.


=== Chapter 7 ===
=== Chapter 11 ===


* (online version only) Last line of first paragraph of Chapter 7.1: "valuees" should be "values."
* (online version only) Chapter 11.3.3: The sentence containing Equation (11.18) is missing a period at the end.
* Just below caption for Figure 7.8: There is an extraneous dot.

=== Chapter 8 ===

* (online version only) Chapter 8.1.1, last paragraph: <math>\dot{\theta}_1</math> is improperly typeset.

=== Chapter 12 ===

* Caption of Figure 12.14, second-to-last sentence: "rotation if possible" should be "rotation is possible."
* (online version only) Example 12.11: The sentence "... can remain standing if there is a consistent solution if there exist <math>k_i \geq 0</math> ..." should read simply "... if there exist <math>k_i \geq 0</math> ..."

=== Chapter 13 ===

* Equation (13.29): <math>y_p</math> should be <math>y_P</math>.


== A partial list of errata contributors ==
== A partial list of errata contributors ==
Line 120: Line 36:
Thanks to the following people who provided corrections, starting from the preliminary version of the book posted in October, 2016:
Thanks to the following people who provided corrections, starting from the preliminary version of the book posted in October, 2016:


H. Andy Nam, Eric Lee, Yuchen Rao, Chainatee Tanakulrongson, Mengjiao Hong, Kevin Cheng, Jens Lundell, Elton Cheng, Michael Young, Jarvis Schultz, Logan Springgate, Sofya Akhmametyeva, Aykut Onol, Josh Holcomb, Yue Chen, Mark Shi, AJ Ibraheem, Yalun Wen, Seongjae Jeong, Josh Mehling, Felix Wang, Drew Warren, Chris Miller, Clemens Eppner, Zack Woodruff, Jian Shi, Jixiang Zhang, Shachar Liberman, Will Wu, Dirk Boysen, Awe Wang, Ville Kyrki, John Troll, Andrew Taylor, Nikhil Bakshi
H. Andy Nam, Eric Lee, Yuchen Rao, Chainatee Tanakulrongson, Mengjiao Hong, Kevin Cheng, Jens Lundell, Elton Cheng, Michael Young, Jarvis Schultz, Logan Springgate, Sofya Akhmametyeva, Aykut Onol, Josh Holcomb, Yue Chen, Mark Shi, AJ Ibraheem, Yalun Wen, Seongjae Jeong, Josh Mehling, Felix Wang, Drew Warren, Chris Miller, Clemens Eppner, Zack Woodruff, Jian Shi, Jixiang Zhang, Shachar Liberman, Will Wu, Dirk Boysen, Awe Wang, Ville Kyrki, John Troll, Andrew Taylor, Nikhil Bakshi, Yunzhe Pan, Barrett Ames, Marcel Bonnici, Mahdiar Edraki

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Revision as of 06:24, 2 April 2020

The errata below are for the updated first edition of Modern Robotics (as well as the practice exercises and linear algebra refresher appendix). The updated first edition (also called "version 2") was originally published by Cambridge University Press in late 2019 (marked "3rd printing 2019" or later) and the corresponding online preprint is dated December 2019. The updated first edition includes several corrections and minor additions to the original first edition, which was originally published by Cambridge in May 2017, with a corresponding online preprint dated May 2017.

The errata for the original first edition can be found here.

Please click here to report any corrections for the updated first edition of the book, the practice exercises, or the linear algebra refresher appendix.

Book: Significant corrections

Chapter 3

  • (printed version only) At the end of the introduction Exercise 3.16, it says "origin of {b} is at (0,2,0) is {s}" but "is {s}" should be "in {s}".
  • Exercise 3.20, Figure 3.26: In the figure, the y and z axes for the {a}, {b}, and {c} frames are switched (y should point forward and z should point up). Also, the space frame is located at the bottom of the small wheel, directly below the {a} frame.
  • (printed version only) Exercise 3.25(a): the element in the third row and third column of the matrix should be 0 (it is incorrectly written as 1).

Chapter 8

  • (printed version only) Equation (8.74): the first two plus signs should be minus signs.

Book: Minor typos, etc., no danger of misunderstanding

Throughout the book

  • The V-REP simulator has been discontinued and replaced by the CoppeliaSim simulator. This does not change anything in the book (or the simulation scenes provided to accompany the book).

Chapter 6

  • (printed version only) Chapter 6.2.2, Example 6.1: just before the matrix , "corresponds to to" should be "corresponds to."
  • (printed version only) Chapter 6.3, first sentence after Equation (6.7): "however small" should be written "however, small" to avoid ambiguity.

Chapter 11

  • (online version only) Chapter 11.3.3: The sentence containing Equation (11.18) is missing a period at the end.

A partial list of errata contributors

Thanks to the following people who provided corrections, starting from the preliminary version of the book posted in October, 2016:

H. Andy Nam, Eric Lee, Yuchen Rao, Chainatee Tanakulrongson, Mengjiao Hong, Kevin Cheng, Jens Lundell, Elton Cheng, Michael Young, Jarvis Schultz, Logan Springgate, Sofya Akhmametyeva, Aykut Onol, Josh Holcomb, Yue Chen, Mark Shi, AJ Ibraheem, Yalun Wen, Seongjae Jeong, Josh Mehling, Felix Wang, Drew Warren, Chris Miller, Clemens Eppner, Zack Woodruff, Jian Shi, Jixiang Zhang, Shachar Liberman, Will Wu, Dirk Boysen, Awe Wang, Ville Kyrki, John Troll, Andrew Taylor, Nikhil Bakshi, Yunzhe Pan, Barrett Ames, Marcel Bonnici, Mahdiar Edraki