Link's Inertia

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ahmed023
Posts: 2
Joined: 01 Apr 2020, 04:06

Link's Inertia

Post by ahmed023 »

Image

in the rigid body dynamics window, under the principal moments of inertia/mass section. The principal moments of inertia IXX IYY IZZ have to be entered relative to shape's frame or absolute frame.

coppelia
Site Admin
Posts: 10375
Joined: 14 Dec 2012, 00:25

Re: Link's Inertia

Post by coppelia »

Hello,

we can't see the picture you posted. But in the Shape dynamics properties dialog: the principal moment of inertia is expressed relative to: shapeFrame * inertiaFrame.

You can also enter inertia data relative to the absolute reference frame by clicking Set inertia matrix and COM relative to absolute frame

Cheers

ahmed023
Posts: 2
Joined: 01 Apr 2020, 04:06

Re: Link's Inertia

Post by ahmed023 »

The image isn't important. What do you mean by shape frame * inertia frame. Also absolute frame means the scene's absolute frame ?

coppelia
Site Admin
Posts: 10375
Joined: 14 Dec 2012, 00:25

Re: Link's Inertia

Post by coppelia »

The world reference frame is the absolute reference frame.
If you take two objects mounted on top of each other, and the first object (parent ) has a local frame A (i.e. local to world)), and the child has a local frame B (i.e. local to frame A), then frame B's absolute reference frame is:

absoluteFrameB=localFrameA*localFrameB

Cheers

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