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Inter-dependant Mates - am I expecting too much or is this a bug.

brett_suttonbrett_sutton Member Posts: 38 ✭✭✭
edited July 2016 in Community Support
I'm trying to model a fairly simple robot arm.


Basically I'm trying to move a segment of the arm using a linear actuator (a threaded rod between the two segments).

The two arm segments and the threaded rod form a triangle. Shortening or lengthening the rod changes the position of the segments relative to each other.

If you look at the assembly I have four inter related mates however the fifth mate (which 'closes' the triangle) causes an error.

Robot arm with four mates
https://cad.onshape.com/documents/95e94cab4009425aa536295c/v/4557c9ceedc34c36a89bf326

Robot arm with fifth mate and error
https://cad.onshape.com/documents/95e94cab4009425aa536295c/v/74f1713dfa684e56ad5130b0/e/d39db2ce3fcb45708f25fed9

The two arm segments are joined with a rotational mate.

Each segment than has an actuator end point 'holder'. The holders are mated to the arm segments using a rotational mate. 

The threaded rod is then inserted into each end point  using a sliding mate.

Now from a simple physical process the geometry of the arm works, however it appears  that onshape  is unable to handle the 'circular' nature of the full set of mates.

Am I expecting too much from onshape mates or is this a bug?
 

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