Rigging a closing tripod legs with hinges?

[280706JENED9]

I'm trying to rig a camera tripod with connecting hinges. As you go to close the tripod, I would like the legs to move towards the center and their hinges to rotate. I am currently using point and aim constraints but cannot seem to find the right combination to get it working (see attached gif).

 

I've also attached the working file to help make it easier to understand my parenting structure.

[mcw0]

This is a straight trig issue.  You know the hypotenuse (length of the leg).  As you raise the leg along the central shaft, the angle = acosd(height on shaft/hypotenuse).

[280706JENED9]

Thank you for the reply @mcw0! While I am following the idea, I am unsure of how to apply it into the rigging system. Could you please elaborate more?

[mcw0]

Measure the length of the leg geometry from rotation pivot to end of leg.  Grab the node that rotates the leg geometry and determine the rotation axis that you want to control.  Create an expression on the rotation channel.  For example, if it's rotateX...

rotateX = acosd(nodeThatLiftsLeg.translateY / lengthOfLeg);

[dinofiguera · Accepted solution]

Create one skeleton joint at each moving pivot position (3 joints) 

connect the joints like a leg, create an IK handle between them.
parent constraint the IK handle to the Up and down control
parent the geometry to the bones and the bones to your main control and you don't need anything else.

Remember to properly orient the joint axes before applying the IK handle...