we choose to use the left side when designing mechanics
we could have easily chosen the right side
Angadh Nanjangud
@angadhn
the basis for the first 3 components and next 3 components are the same
actually they are completely different!
Jason K. Moore
@moorepants
the basis is defined in A
they are the same!
Angadh Nanjangud
@angadhn
no!
V = [velocity, angular vleocity]
V is spatial veclotiy
V != v + w
V_linVel = v
V_angVel = angular velocity
they are components of tow different vectors
they do not live in R6
but actually in R3cross3
Jason K. Moore
@moorepants
you can write it like SpatialVector(v, w, A) if you want
same thing
Angadh Nanjangud
@angadhn
which is what I offer
Jason K. Moore
@moorepants
gotta go bye
Angadh Nanjangud
@angadhn
if you look at attributes, it V.w and V.v
later!
also from the book: "Strictly speaking spatial vectors live in the R3×R3 space, but for notational simplicity we will treat them as members of the R6 space."
my point is that spatial velocity is not a sum of angular and linear velocities
yibochallinger
@yibochallinger
is there a good example using pydy.viz?
yibochallinger
@yibochallinger
@moorepants where to find the code to Conical Pendulum Visualization with PyDy? did you generate javascript from python?
It stated that it's using pydy, would like to know if there is any more of this.
Jason K. Moore
@moorepants
@extraymond looks interesting, didn't know about it, seems you can't download it without an account on that website
extraymond
@extraymond
@moorepants I've been looking for reference files or citing about this document, but nothing but the one on scribd.com can be found.
yibochallinger
@yibochallinger
I followed pydy tutorial human standing example hoping to create a visualization for a quadcopter but pydy.viz doesn't display any objects.
Renato Marinho
@renatomarinho
This message was deleted
Renato Marinho
@renatomarinho
This message was deleted
Sam Brockie
@brocksam
Hi. What's the simplest way to extract numerical values for Derivative(u, t) from a pydy System object following running System.integrate()? I know System.integrate() returns a np.ndarray with each column corresponding to the vector of q and u states for the system. But if one derives the EoM with auxiliary speeds to bring into evidence noncontributing forces then these can be functions of the time derivatives of the speeds. Or is there a more efficient way to numerically evaluate these noncontributing forces from the auxiliary equations? Many thanks, Sam
Jason K. Moore
@moorepants
The system object currently does not track anything extra. You can lambdify the expressions you want to calculate and then provide the results from system.integrate() to the function generated from lambdify.
extraymond
@extraymond
@yibochallinger If your using jupyter lab, I think the widget is coming out like what it does with jupyter notebook.
Foad Sojoodi Farimani
@fsfarimani_twitter
Hey guys, I'm very new to PyDy. I was wondering if there are any examples for 1. 3D mechanisms 2. parallel / closed mechanisms? Thanks for your help in advance
Foad Sojoodi Farimani
@fsfarimani_twitter
Hi everybody, I opened a new issue pydy/pydy#412 I would appreciate if you could help me find a solution. Thanks in advance.
Foad Sojoodi Farimani
@fsfarimani_twitter
the link to "Inverted pendulum model of a standing human" on this page seems to be broken as I have reported pydy/pydy#413
Foad Sojoodi Farimani
@fsfarimani_twitter
Hi guys, I would appreciate if you could help me with this question from Kane 1985 book.