I'm working on rigging the actuator arms for the landing gear doors on a project and have run into an irritating problem. When the doors are open everything is fine:

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However when the door closes:

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As you can see, it flips the arm 180 degrees. This is happening to all three actuator arms. I have it rigged as follows:

1) The door itself is parented to the armature that actually rotates the hinge.

2) I'm using empties and track to constraints to animate the actuator arms.

3) The actuator sleeve (the upper half with the ball joint) is parented to an empty called Upper, which the acuator piston (with the arm) is Tracked to.

4) Vice versa for the Lower empty.

5) Lower is parented to the door object, and moves with the door. Upper remains stationary as it's fixed to the bay (no parenting).

This is one of my main landing gear bays. I'm using a similar setup for the forward bay doors, which are NOT experiencing this issue.

I just remodeled and repositioned the actuators so they stop flipping. They're not exactly where I wanted then to be, but they work proper in the new spots, so all good.

  • $\begingroup$ I'm no rigging expert, but... maybe it's just taking the shortest path to rotate and maybe this can be fixed with an IK pole target. $\endgroup$ – Mentalist Oct 26 '15 at 0:27
  • $\begingroup$ I don't think that will work, as the piston doesn't have any bones itself. It's entirely using the Empties and track constraints to animate when the door open and closes. I think I got what I needed though, by changing it to a Locked Track Constraint, but wanted to see if there were any other options before marking this answersed. $\endgroup$ – Ambaryerno Oct 26 '15 at 0:58
  • $\begingroup$ Nevermind, Locked Track didn't work either. That just screws up the piston in other ways. $\endgroup$ – Ambaryerno Oct 26 '15 at 1:04
  • $\begingroup$ I have a feeling you may need to use an armature for this. $\endgroup$ – Mentalist Oct 26 '15 at 1:15
  • $\begingroup$ The problem is the forward gear bay doors are set up the same way and AREN'T doing this. $\endgroup$ – Ambaryerno Oct 26 '15 at 1:34