State space model of mass spring damper with base excitation

• Jul 1, 2020

• #2

IRstuff

Aerospace

Jun 3, 2002

44,772

perhaps this:

http://ocw.snu.ac.kr/sites/default/files/NOTE/10896.pdf

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• Jul 2, 2020

• Thread starter
• #3

SC83

Mechanical

Jun 8, 2018

24

Hi IRstuff,

Thank you for the link.
This is almost what I'm looking for (slide 52). However, I'm struggling to write the harmonic forcing functions (2.63) in state-space format (B matrix). Analytical, they do a superposition of the two individual particular solutions. Have you an idea of how this done in state-space format?

 

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• Jul 2, 2020

• #4

xnuke

Electrical

May 3, 1999

1,029

Forcing functions are inputs that are external to the state space model. They don't go in the B matrix, but are in the u term, assuming xdot = Ax + Bu; y = Cx + Du.

xnuke
"Live and act within the limit of your knowledge and keep expanding it to the limit of your life." Ayn Rand, Atlas Shrugged.
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• Jul 2, 2020

• Thread starter
• #5

SC83

Mechanical

Jun 8, 2018

24

Hi xnuke,

Thank you for your reply.
So my B matrix is: [0; 1/m]
And u is: bWY cos (Wt) + kY sin (Wt)
If xdot is: [x'; x'']

Right?

Steven

 

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• Jul 2, 2020

• #6

PNachtwey

Electrical

Oct 9, 2004

779

I have a video that does step jumps in the set point and also sine waves.

https://www.youtube.com/watch?v=OxRJZSn07vI

My Peter Ponders PID channel has a lot of good info


Peter Nachtwey
Delta Computer Systems

http://www.deltamotion.com

http://forum.deltamotion.com/

 

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• Jul 2, 2020

• #7

xnuke

Electrical

May 3, 1999

1,029

Steven, that looks correct for u and B based on your definition of the state vector.

xnuke
"Live and act within the limit of your knowledge and keep expanding it to the limit of your life." Ayn Rand, Atlas Shrugged.
Please see FAQ731-376 for tips on how to make the best use of Eng-Tips.

 

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• Jul 2, 2020

• Thread starter
• #8

SC83

Mechanical

Jun 8, 2018

24

Thank you!

 

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