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Assignment 7 (posted on March 4)

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Dan Negrut

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Unread post Thu Mar 04, 2010 4:55 pm

Assignment 7 (posted on March 4)

please post questions related to HW7 under this discussion thread.  if you see questions for which you can provide an answer, please do so.
thank you.
dan
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Dan Negrut

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Unread post Fri Mar 05, 2010 1:39 pm

Re: Assignment 7 (posted on March 4)

This is a message i got from an ME751 student:
I would post this on the forum but there is no 'board' to post to. The HW7 asks us to use code for DP1 to look at a pendulum. When will we get HW6 back to know if our code is correct? I don't want to get points off on HW7 b/c I have faulty code from HW6.


First, if you log in on the Forum, there is a "Reply" button.  Select that to reply to a previous posting.

Second, you will probably get back HW6 next week sometime.  For now, I didn't ask you to run a kinematics analysis to generate the time evolution of the pendulum.  You were only asked to generate some quantities. If they are slightly off, you are not going to get your simulation to diverge, crash, enter an infinite loop, etc.  To conclude, build on what you have and will be good.  For HW8 you will indeed need to have the correct ingredients for the simulation to run ok.  Will cross that bridge when we get to it. 
dan
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ME451Tyler

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Unread post Wed Mar 10, 2010 9:35 am

Re: Assignment 7 (posted on March 4)

For the DP2 constraint, can we say a_bar is the vector from the point P to Q on body i?  (This is how a_bar is defined in DP1)
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ME451Tyler

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Unread post Wed Mar 10, 2010 9:47 am

Re: Assignment 7 (posted on March 4)

Also, gammaD from 0218 slide 21.

Second to last term beginning 2*dij

Aj*omega_j_bar_cross*omega_j_bar_cross*s_j_bar^Q

(3x3)(3x3)(3x3)(3x1) --> (3x1)

dij --> (3x1)

You can't multiply these two.  Should dij be dij^T?
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ME751Chris

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Unread post Wed Mar 10, 2010 9:19 pm

Re: Assignment 7 (posted on March 4)

Do we put in r_dot or is there a way to express r_dot in a different way?
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ME751Anne

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Unread post Wed Mar 10, 2010 9:37 pm

Re: Assignment 7 (posted on March 4)

gammaD: I posted a slide correction saying the same thing. d_ij should be transposed
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ME751Anne

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Unread post Wed Mar 10, 2010 9:37 pm

Re: Assignment 7 (posted on March 4)

Christopher: you need to specify these initial velocities in your input file.
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ME751Chris

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Unread post Thu Mar 11, 2010 1:49 am

Re: Assignment 7 (posted on March 4)

So...normalization constraint?  Are we to implement this and have this as an output?  How do we go about doing this?
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ME751Chris

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Unread post Thu Mar 11, 2010 3:12 am

Re: Assignment 7 (posted on March 4)

The directions say generate the file me751HW7.mdl file.  Does that mean it should be generated by MATLAB (like using fprintf etc?).  Or by generate you mean that we type it up by hand like HW6?
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Dan Negrut

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Unread post Thu Mar 11, 2010 8:03 am

Re: Assignment 7 (posted on March 4)

Type it like for HW6.
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ME751Anne

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Unread post Fri Mar 12, 2010 2:20 pm

Re: Assignment 7 (posted on March 4)

I implemented the normalization constraint like I did the other constraints.

As for the mdl file, I have a program that writes this text file if you give it a point in time. I think this will be useful for hw8.
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ME751Arman

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Unread post Mon Mar 15, 2010 9:37 am

Re: Assignment 7 (posted on March 4)

I wanted to use some parts from someone else's code. Is HW7 codes going to be uploaded?
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Dan Negrut

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Unread post Mon Mar 15, 2010 1:33 pm

Re: Assignment 7 (posted on March 4)

ME751Arman wrote:I wanted to use some parts from someone else's code. Is HW7 codes going to be uploaded?

Naresh should upload all of them today.  There were three students who ran late with their HW and didn't want to post the solution before Monday 9:30 am.
dan

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