Anatomy of Concept:
Nulls drive the translation of the spring constraints.
Spring(s) contraint drives geometry movement.
Steps for Creation:
2 cylinders, 1 translated +3 X, 1 translated -3 X
1 cube, tweak as needed, position it along the Z & Y. (see below)
Draw joints and create an IK Rotate Plane Solution for each (see below).
Parent each respective Ik Handle to "its" Cylinder. (see below)
Parent each respective start joint to the "sled" geometry.
Create a null and make it the parent of the "sled" geometry. (see below)
Create 2 spring contraints for the cube (sled) geometry
Translate 1 spring constraint -4 X and the other +4 X.
More Spring Constraints:
Create 2 spring constraints per cylinder and translate one +4Y and one -4Y (for each).
Create a null for both the upper constraints and a null for the lower constraints.
Position the nulls according to the Y axis of their respective spring constraints.
Free translations on the nulls.
Make the corresponding null the parent of the corresponding constraints (upper or lower) (See below)
For additional control, add more constraints per your needs. (see below)
Animate the Null Controllers and playback the scene.
Adjust your springs and see how they enhance your scene.
This is a rough quick idea to get you started in the land of dynamic constraints!
* PLAY TIME - EXPIRIMENT HEAVILY!!!
Full Tutorial with Scene Files available at n8Dog.com
Got complaints? Please email it to yourself.