Gear mate in anybody

Main Forum
1

Hi !

I would like to know if there is a way to represent the motion of two gears in anybody. I need to represent a knee orthosis with a gear system to make the motion, but I don't know how to do it in anybody. Is there a way to link the rotation of two hinges so that both move at the same time, but in different directions ? Gear mates from Solidworks are not supported by the AnyExp4SOLIDWORKS extension.

Best regards,
Xavier.

2

Hi @emeric.bernier

Is it primarily for visual or for the mechanical part you want to model it?

For the mechanical part maybe you could maybe compute the equivalent torque and apply that to the human model? that is much easier than modeling gears with contact surfaces.
For the visual part you could create a segment, apply the gear stl. and set a rotation for it so it moves correctly.

Forgive me if I misunderstood some aspect of your scenario but I hope it helps

Best regards,
Bjørn
AnyBody Technology

3

Hi Xavier,

I think you can do this by creating a linear combination measure between the two rotations and with the coefficient as the gearing ratio. Look up the AnyKinLinComp class. You can use this measure in a kinematic constraint equation created with the AnyKinEq class. Effectively, this will allow you to write the following equation:

Theta1 -N*Theta2 = 0 . If you keep the reaction force on in the contraint equation, it will also correctly transfer the moment between the two connected segments.

Best regards
Michael

4

Hi Michael,

Thank you very much for your help!
It is in fact what I was looking for.

Best regards,
Xavier.

5

Hi,

The angle value of the gear 1 is a AnyFloat variable so I can't use it with AnyKinMeasureLinComb. Is there a way to link a AnyFloat variable of angle (first gear) that changes with frames to the rotation of another gear ?

Thank you very much for your time,
Xavier.

6

Hi Xavier,

You will need to use the angle value for gear 1 to make a driver for the rotation of that body. Start with that.

Then create the second body and make it rotate with the gear ratio relative to the first body using the approach I outlined above. I think it could also make sense for you to review the tutorials on kinematic measures and drivers to help you along.

Best regards
Michael

7

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