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moorepants / learn-multibody-dynamics

Interactive computational book on multibody dynamics
https://moorepants.github.io/learn-multibody-dynamics/
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Use Mk,gk instead of Yk,zk #182

Open moorepants opened 7 months ago

moorepants commented 7 months ago

I use $Y_k\dot{\bar{q}} + z_k - \bar{u}=0$ when introducing kinematic differential equations but then use the notation $\mathbf{M}_k \dot{\bar{q}} + \bar{g}_k = 0$ later. M_k is Y_k and g_k is zk-u, so I should just use one of these notations. I could change to only using the Mk,gk form.

Peter230655 commented 7 months ago

I assume, you compare eq (110) to eq (201) in your script (?)

  1. In eq (110) in your lecture, the dot seems to be 'inside' of the q, rather than on top of it, at least so it looks on my screen.
  2. IF I am looking at the equations you mean, does eq (201) not assume that $\bar u = I \dot{\bar q}$ ?
moorepants commented 7 months ago

When viewing with Firefox on my computer this is what I see for Eq 110: image

moorepants commented 7 months ago

Eq 201 is this for me: image First equation on https://moorepants.github.io/learn-multibody-dynamics/nonholonomic-eom.html

So I'm not sure if that is the equation you meant to refer to.

Peter230655 commented 7 months ago

Eq (110): I opened your lecture from GitHub. Your display looks right, must be an issue with mine. image

Eq (201): Yes, this is the one I meant in my reply. Which equation did you refer to originally?

moorepants commented 7 months ago

I was referring to 191.

Regardless, 201 does not assume u = q'.

moorepants commented 7 months ago

Eq (110): I opened your lecture from GitHub. Your display looks right, must be an issue with mine.

What web browser do you use? The math rendering is handled by MathJax + your web browser. Maybe Mathjax has a bug that shows on your browser.

Peter230655 commented 7 months ago

I use Firefox, I believe. Maybe an issue with my internet, right now, I does not 'translate' your lecture from 'latex' to 'English at all. Maybe again right this afternoon?

Peter230655 commented 7 months ago

I think, maybe $M_k$ is better as it 'indicates' the 'mass matrix of the kinematic DEs.' NB: Now my equation (110) is displayed well. Must have been an internet problem this morning.