If you want to constrain multiple rigid bodies in a chain-like fashion, you use the command. After you choose a constraint command, a picking session begins in which you need to pick the constrained and constraining
In this example, you will constrain object A to B, B to C, and C to D. Object D (the cube) is a passive rigid body, which
acts as an anchor for the other active rigid bodies.
To chain-link rigid bodies with constraints
Choose a constraint from the menu in the Simulate toolbar: , , , , or .
The Hinge or Ball and Socket constraints are usually the most useful.
Left-click to pick the first object to be constrained (A).
Middle-click the rest of the objects in the order you want them to be connected together (B, C, D).
Right-click to end the picking mode.
Hinge constraints with multiple rigid bodies in a chain. Objects A, B, and C are active and object D is passive. Notice how
each constraint object is attached to each constrained objects' centers.
Creating "Rag Doll" Skeletons
While you cannot apply rigid body to chains (skeletons), you can build a skeletal structure ("rag doll") by linking several
rigid bodies together as limbs with hinge or ball-and-socket constraints.
Then constrain your chain skeleton to this rag doll rig. Once you have the effect you want, plot the motion on the rag doll
rig, and then transfer that motion to the chain skeleton.