Can somethig be assumed for the 12 parameters Y... ? Are they real or positive?

@OrangVahid 

Yes, the physics are correct as I have tired to explain in my reply "Physics" to Rouben Rostamian. I see in your animation the contact force at the contact point animated. Visualising the contact point and contact forces (and slipage) is one of the features I would like to see one day.

In a planar case I could probably find a way to visualize such things but in 3d including multiple contacts I cannot see how this can be done with the standard library. 

Thank you for following up on this.

@OrangVahid 

Yes, it vanishes when the number of plot points in the simulation settings are increased or the simulation time is reduced.

@Rouben Rostamian  

Beautiful. It's kind of a double pendulum that is not chaotic. I have to think about it (and how to make it chaotic)

@mmcdara 

Thank you too. MapleSim is a good explorative tool but also kind of a grey box. The governing equations of motion are not intended to be easily understandable. MapleSim assembles them for efficient computation.
For example, I have not found a good explanation why the vector of agular acceleration (orange) is perpendicular to the initial axis of rotation. Note also the flip the red and green forces.

For a further analysis, I think, Maple has to be involved.

@Mariusz Iwaniuk 
What about solutions exploiting symmetry?

int(cos(cos(x)),x=0..1/2*Pi)
                       1                 
                       - Pi BesselJ(0, 1)
                       2                 

and 3/2 Pi, ...

Here again Maple does not take periodicy into account.

Or:

int(sin(sin(x)),x=0..3/2*Pi)

I am wondering whether Mma hard codes such results or uses an algorithm that identifies periodicy.

By the way: AI does not know the answer to any of those integrals (yet).

@Christopher2222 

The fix: Deleting all demultiplexers and inserting new ones from the library.

@Christopher2222 

Thank you. In this case MapleSim was particulary good to quickly explore things and to get numerical results.

@Christopher2222 

The post is worth emphasizing. It provides clean and documented Maple code for the equations of motion by Rouben Rostamian using quaternions. 

@Carl Love

Since I had to leave mechanics a long time ago, I would need feedback and advice on what is worth publishing and where. I have no idea which part could offer added value in which (scientific) domain.

A journal like Maple Transaction would be suitable but such a thing does not seem to exist for work mostly done with MapleSim. Perhaps @rcorless can tell how much explicit Maple must be inside a Maple Transaction publication.

I am pleased that the post could provide more than only details on MapleSoft tools.

@nm 

I can confirm the errors and that it is not fully reproducible (no clear pattern) as one would expect.

I can also confrim that with Maple 2022 I do not see the error messages at all.

This is a nasty bug.

If I had time I would now compare Maple 2022 and 2024 side by side or I would look for a case that is 100% reproducible.

The explanations for the partial cylinder geometry in

?componentLibrary,multibody,visualization,CylindricalGeometry

helped to understand what to do.

(Its the first time I use this component. Beginner error: Wrong intuition and wrong interpretation of the orientation of the base frame in the help page.)

@mayzal 

I cannot find that you set boundary conditions for velocity_dimensionless when I enter.

indets({BCS})

Please check

I have no experience with pdsolve but the error message indicates the that the problem is related to the definition of the BCs.

It could either be that there is a pde too much for one of the depended variables or that one depended variable does not depend on time.

You have in total 7 dependend variables 

P_dimensionless(z, t), T_dimensionless(z, t), Tw_dimensionless(z, t), velocity_dimensionless(z, t), X_dimensionless[1](z, t), X_dimensionless[2](z, t), Y_dimensionless[1](z, t)

8 boundary conditions and 6 initial conditions. Is that correct and what you want to do? Is it further correct that two of the boundary conditions depend on other boundaray conditions? Maybe Maple cannot deal with such combined BCS.

I am affraid that I cannot help further but perhaps this clarification can kick-off answers.

@Samir Khan 

Why not installing the previous version until a fix is available?