needle insertion

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woodstock94
Posts: 2
Joined: 13 Sep 2017, 09:55

needle insertion

Postby woodstock94 » 13 Sep 2017, 10:12

hi guys,
I'm working on a simulation where a needle, located at the end effector of a kuka LBR4+, try to operate an insertion over a tissue.
I'm ok with moving the robot and I approximated the needle with a cone primitive shape. Still I don't know how to simulate a perforation, I need the needle to be inserted inside an object in order to simulate an insertion on the skin, then fat, then muscle.
Is there a way to modify the properties of an object? Is there a way to perform a perforation over an object?
Hope the question is clear, thanks a lot!

coppelia
Site Admin
Posts: 6058
Joined: 14 Dec 2012, 00:25

Re: needle insertion

Postby coppelia » 13 Sep 2017, 14:47

Hello,

this is a difficult task for several reasons. How I would do it is really overkill, but the only way I see this more or less feasable:

  • Use a cuboid as the needle. For the hole, use several cuboids (e.g. min. 3, ideally 8 or more) grouped to form a hole. The hole can also dynamically be put into place once the needle is supposed to perforate the tissue. Once the tissue is perforated, the hole stays in place to keep the needle from shifting sideways. Make the friction between hole and the needle 0.
  • To mimic resistance from the tissue(s), you could place another cuboid below the hole. That cuboid would be attached to a spring/damper joint, where you could modify the spring and damping parameters on the fly, to mimic various tissues. Or maybe, instead of using a spring-damper model for the joint, you could use a joint with a counter-force, that resists insertion.
  • Another option would be to directly apply resistive forces to the needle when it drives into the tissue

Cheers

woodstock94
Posts: 2
Joined: 13 Sep 2017, 09:55

Re: needle insertion

Postby woodstock94 » 13 Sep 2017, 16:07

First of all thank you for the quick answer!

I'm not sure to have understood the whole answer.
The first point is fine.
Can you please explain better second and third points?

thanks for the patience! :)


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