Vargas' book about Differential Geometry

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Discussion Overview

The discussion revolves around the use of Differential Geometry (DG) in robotics, particularly in relation to Vargas's book on the subject. Participants explore different approaches to learning DG, the applicability of various texts, and the integration of mechanics with robotics, especially in the context of reinforcement learning.

Discussion Character

  • Exploratory
  • Debate/contested
  • Technical explanation
  • Mathematical reasoning

Main Points Raised

  • One participant expresses concern about Vargas's book being opinionated and questions whether it is a suitable starting point for learning DG compared to more popular texts like Boothby's.
  • Another participant mentions their interest in locomotion and the relevance of DG to modern mechanics, indicating a desire to combine it with reinforcement learning.
  • A participant critiques Vargas's book for being difficult to read due to the author's premature references to concepts, preferring Victor Guillemin's notes instead.
  • One participant suggests avoiding modern geometrical approaches to mechanics for practical robotics applications, advocating for traditional physical/engineering presentations instead.
  • Several participants inquire about the specific applications of DG in robotics, mentioning aspects like joint motion and path planning.
  • A participant discusses their focus on underactuated robotics and nonholonomic mechanics, expressing a desire to learn more about dynamics to enhance reinforcement learning algorithms.
  • Another participant comments on the perceived abstraction of more mathematical texts, suggesting that while abstraction aids in understanding, it may not be practical for solving specific problems.
  • One participant emphasizes the importance of learning sufficient mathematics to engage with relevant literature in the field, sharing their own experience with measure theory.

Areas of Agreement / Disagreement

Participants express differing opinions on the suitability of Vargas's book and the best approach to learning DG for robotics. There is no consensus on whether modern geometrical methods or traditional presentations are more beneficial for practical applications. The discussion remains unresolved regarding the optimal resources and methods for integrating DG with robotics.

Contextual Notes

Participants highlight the complexity of learning DG and its applications, noting the potential challenges of abstraction in mathematical texts and the need for background study in related areas such as dynamics and mechanics.

kiuhnm
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I'm learning Differential Geometry (DG) on my own (I need it for robotics). I realized that there are many approaches to DG and one is Cartan's, which is presented in Vargas's book. I think that book is highly opinionated, but I don't know if that's a good or bad thing. Does anyone of you know that book or the approach described in it? More importantly, should I start from this book or should I first learn the popular way (e.g. from Boothby's book)?
 
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kiuhnm said:
(I need it for robotics)
May I ask how differential geometry is needed for robotics? :wideeyed:
 
I'm interested in locomotion and the modern formulation of mechanics relies on Differential Geometry. I come from Reinforcement Learning and want to know more about mechanics and dynamics to see if I can combine the two approaches.

Anyway, I don't like Vargas's book. It's almost unreadable because the author refers to concepts before defining or explaining them. I'm reading Victor Guillemin's notes right now and I like them.
 
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If you want to apply mechanics to something practical (such as making a robot), then I would suggest you to avoid modern geometrical approaches to mechanics. A good old physical/engineering presentation of mechanics should be much more useful for practical purposes. Or perhaps you are doing general abstract theory of robotics without attempting to actually make a robot?
 
Demystifier said:
May I ask how differential geometry is needed for robotics? :wideeyed:

There could be a few ways- motion of a jointed arm (for example), involves coordinate transformations. Trying to move a tool along a prescribed path is another. I've seen differential geometry appear in gear theory as well:

https://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19900010277.pdf
 
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Demystifier said:
May I ask how differential geometry is needed for robotics? :wideeyed:

I'm focusing on underactuated robotics which is related to nonholonomic mechanics. I've been ignoring the dynamics part so far because I've been using Reinforcement Learning, which is basically an approach where an agent figures out on its own how to maximize a reward signal. If the reward signal indicates how fast an agent is running, then the agent will learn how to run (with mixed results because of bad local minima).
That approach is very promising but I think it's not enough so I want to learn about dynamics and see if dynamics and mechanics can inform the RL algorithms in a useful way.
Here's the most recent and complete book I could find about nonholonomic mechanics: https://www.amazon.com/dp/1493930168/?tag=pfamazon01-20
It looks pretty advanced so I need to do some background study. Goldstein's book is a classic but I think that José & Saletan or Fasano & Marmi are better suited for my purpose, being more mathematical.
 
kiuhnm said:
Goldstein's book is a classic but I think that José & Saletan or Fasano & Marmi are better suited for my purpose, being more mathematical.
In my experience (I am a theoretical physicist) "more mathematical" usually means more abstract, and hence less applicable. Abstraction is good for understanding the big picture, but not for solving specific practical problems. Nevertheless, you certainly know better what is better suited for you.
 
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Demystifier said:
In my experience (I am a theoretical physicist) "more mathematical" usually means more abstract, and hence less applicable. Abstraction is good for understanding the big picture, but not for solving specific practical problems. Nevertheless, you certainly know better what is better suited for you.

I think one should learn enough math to be able to read and understand most papers and books relevant to its field. For instance I had to learn some measure theory just to be able to read some overly mathematical papers and that certainly paid off.
 

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