GSoC Introduction & question

[Timo Stienstra]

Hello everyone,

My name is Timo Stienstra. After completing my BSc. Mechanical Engineering with a minor Computer Science, I am now in my first year MSc. Mechanical Engineering student at Delft University of Technology. Here I follow the track BioMechanical Design, where I also specialize myself in robotics.

I am interested in contributing to the mechanics module of SymPy, but for GSoC I would specifically like to focus on further developing construction of systems from bodies and joints.

However I am not sure how to interpret one of the suggested next steps, namely Make the rotations quaternion based. Could someone elaborate on what is meant with this step?

I know that the orientation of the child body with respect to the parent could be described by a quaternion, but the orientation is in the end saved as a rotation matrix within the ReferenceFrame objects. And I do not think that the goal of this step is changing this in the ReferenceFrame class.

Regards,

Timo Stienstra

GitHub: https://github.com/TJStienstra

[Aaron Meurer]

Hi Timo and welcome.

Someone who has more knowledge of the mechanics module will need to
answer your specific question about quaternions. I will point out that
SymPy does have a quaternions module in sympy.algebras.quaternions, so
you would most likely want to make use of that for that project.

If you haven't seen it already, be aware of the patch requirement for
GSoC. https://github.com/sympy/sympy/wiki/GSoC-Student-Instructions.
You will need to make at least one pull request to SymPy that gets
accepted. It doesn't necessarily have to be related to your project,
so you can start by finding a bug to fix.

Aaron Meurer

> --
> You received this message because you are subscribed to the Google Groups "sympy" group.
> To unsubscribe from this group and stop receiving emails from it, send an email to sympy+un...@googlegroups.com.
> To view this discussion on the web visit https://groups.google.com/d/msgid/sympy/79a38c56-e280-4591-8ac0-11823c9e27e7n%40googlegroups.com.

[Alan Bromborsky]

If you have an interest in quaternions you might find the following link
of interest -

https://galgebra.readthedocs.io/en/latest/

and the following mechanics book -

https://smile.amazon.com/Foundations-Classical-Mechanics-Fundamental-1999-09-30/dp/B01FEKI34A/ref=sr_1_4?crid=1U2EBC2UI9BL9&keywords=david+hestenes&qid=1649362231&sprefix=david+hestenes%2Caps%2C50&sr=8-4

[Timo Stienstra]

Thanks for the information. I did already notice the sympy.algebras.quaternions module, which I will probably use.

About the pull request. I have commented on this one a better solution, but it is currently not linked to an issue. Should I checkout to this PR revert the changes and implement the suggestion I made?

Op donderdag 7 april 2022 om 22:12:07 UTC+2 schreef brombo:

[Aaron Meurer]

It looks like that pull request hasn't had any changes since 2017. It
would be a good idea to start a new pull request if you want to work
on it. If you reuse the work from that PR, be sure to leave the commit
history intact (create your branch based off of Angadh's branch). If
the plan is to start from scratch you don't need to do this.

Aaron Meurer

> To view this discussion on the web visit https://groups.google.com/d/msgid/sympy/0b315521-08f2-4563-9079-5e0f90ffef24n%40googlegroups.com.