I just want to submit you a tutorial writed by a friend, meltingman. He speaks just a little of english so I maked the translation (with the second read of Zelouille).
The aim of this tutorial is to simulate easily a weight constraint in Blender, and especially with the less of calculations as possible.
You can find this tutorial here >> http://melting.perso.orange.fr/tele/meltingtutSoftik_trad.pdf
I’ll make the link between you and meltingman, if you have any comment of course