Vector IK is a great technique for some situations where normal IK just doesn’t cut it. The technique basically uses one control to rotate and “curl” an IK chain. It’s also fairly simple to do.
You can see the basic setup of the rig above. You have an IK chain (make sure to pre-arch it a little to guide the IK solver) whose handle is parented to the main control bone. When you scale the main control bone, it’ll curl the IK chain. Add a pole vec that’s also parented to the main control bone and you’re done.
I use this rig for hand controls, where it works great (I was originally introduced to it by studying one of Bassam Kurdali’s hand rigs in fact). I’ve also heard of people using it to control arms, though I’m a little weary of trying it myself.
