About Human Body Joint angle constraints

[Gökçe Güven]

Hi, 

Nice to meet you first of all. I am a Phd candidate in Computer Science, and currently working on my thesis project which is about extraction of human balance parameters from humans via AI algorithms. I would like to ask a question about joint angle constraints. Sorry if my question is too basic or not, (my background is computational natural science and material science & engineering) sometimes I get stuck in really simple things. 

After working on human balance tutorial, I added a toe to the system, to create an environment for my research project. I need to define joint angle, and angular velocity constraints to my system. As I understand joint angle and angular velocity constraints are belong to non-holonomic constraints. Only thing that I found from web is this link:

https://docs.sympy.org/latest/modules/physics/mechanics/kane.html

And, there it says:

The constraints need to be supplied in a list of expressions which are equal to zero, trivial motion and configuration constraints. 

I did not understand the need for using a list of expression which are equal to zero. I have a max and min angle/angular velocities for basic human body system, and I cannot add my constraints to my system. How should I create a min, max expression for each joint? May you help me about this problem? 

Thanks in advance 

Kind regards,

Gokce Guven

[Jason Moore]

Pin joints add holonomic constraints. The tutorial does not have any non-holonomic constraints.

Jason

moorepants.info
+01 530-601-9791

--
You received this message because you are subscribed to the Google Groups "PyDy" group.
To unsubscribe from this group and stop receiving emails from it, send an email to pydy+uns...@googlegroups.com.
To post to this group, send email to py...@googlegroups.com.
Visit this group at https://groups.google.com/group/pydy.
For more options, visit https://groups.google.com/d/optout.

[Jason Moore]

If you want to specific joint angles with a max/min you can potentially use SymPy's Piecewise function, but I don't think they will work with KanesMethod or LagrangesMethod, in general, but maybe. I've never tried it. If you want limits to motion in joints should should more than likely be creating forces or torques that increase in magnitude the closer your joint gets to the desired limit.

Jason

moorepants.info
+01 530-601-9791

[Gökçe Güven]

Hi,

Thank you so much for your help.

Have a nice day