Negative mass adjustment in RRa

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Valentina Gallego
Posts: 29
Joined: Wed Jan 10, 2018 3:45 pm

Negative mass adjustment in RRa

Post by Valentina Gallego » Fri Jun 08, 2018 9:51 am

Hello!
I'm running the RRA tool for a squat performed with no weights (so I have no external loads) and my model has a weld constraint in the foot since I have no grf and my RRA gives me a huge negative mass adjustment -1.2123e+008
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Dimitar Stanev
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Joined: Fri Jan 31, 2014 5:14 am

Re: Negative mass adjustment in RRa

Post by Dimitar Stanev » Mon Jun 11, 2018 2:13 am

Hi,

It is probably because you haven't defined the ground reaction forces and maybe the constraints are developing large forces due to kinematic mismatch. I have also experimented using weld constraints for constraining the feet on the ground when there are not GRF measurements, but I was unsuccessful.
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Valentina Gallego
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Joined: Wed Jan 10, 2018 3:45 pm

Re: Negative mass adjustment in RRa

Post by Valentina Gallego » Mon Jun 11, 2018 7:13 am

Hello Dimitar,

"It is probably because you haven't defined the ground reaction forces "
how do I define them if don't have them??
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