Complex joint combinations - Fusion 360 limitations?

[calebc01]

I have a design for a 6 degree-of-freedom Stewart Platform that utilizes 6 linear actuators.  See the attached screencast to see it in action.  The set of joints used in this design *should be OK, and realizable in the real world.  But Fusion 360 reports that most of the joints are invalid, even though the assembly sort of works.

For each actuator, motion is constrained with the following combination of joints: Ball joint -> revolute joint -> linear slide -> revolute -> revolute.  With six combinations of those joints, the solution space is huge.  Is Fusion 360 just not capable of handling assemblies with such complex motion constraints?

[calebc01]

Here's the screencast showing the joints working, if only sporadically, despite Fusion 360 reporting that the joints are invalid.

[TrippyLighting · Accepted solution]

This is hard to analyze without having access to the the design, but here are a few suggestions. Set proper joint limits to limit the space in which Fusion. has to solve for joints.

Also, I see you have any position capture features in your timeline. Usually in simple assembly (simple in terms of number of components) this is not necessary. Evaluate whether there are really needed in of. not delete. Each of these position capture features captures the locations of all components in the design with a few exceptions.I believe it does not do this for grounded parts.

That is a lot of data that might not be needed,

[calebc01]

Thanks, I'll add limits and give it a try.

I never actually understood the workflow around position captures - I tended to just drag stuff around for convenience in accessing features to make joints, and captured positions because it asked if I wanted to.

[calebc01]

Hey, adding additional limits did the trick!  I don't know how the solver works, but I'd guess that it was getting stuck in a local minimum without a clear path to a solution that worked.  Thanks for the tip!