Set Up #8 Arm Placement

This next post will talk about the placement for the arm joints. I did have to research a little bit about some placement of bones in the arms. I learnt that the actual name for the Collar Bone is actually called a Clavicle and what that does is that in some models it acts as the shoulder. It acts as a strut for the shoulder - allowing the arm to move away from the body.

With that in mind, I decided to get started on the joints for the arm (Fig 1). 

Fig 1: Image of the left clavicle. The red circle shows the placement of the joint.

Fig 2: The Joint placements in the left arm

Fig 2.2: Joint placements in the left arm, top perspective

The rest of the joint placements are as followed, leftClavicle, leftShoulder, leftElbow and leftWrist. For what it's worth, I did create a joint called leftForearm (Fig 2 and 2.2). The main reason for this was that I tried to create some sort of twist you see when you rotate your wrist. Essentially you'd add an expression to the wrist that would rotate the forearm by x amount (I can't remember the equation you use for it) but I attempted it the exact same way it was supposed too but it didn't work, eventually I figured it would be best to leave that out.

Now that was done, I had to create the IK handles within the arm. I used a IK Rotate-Plan Solver from joints leftClavicle to the leftShoulder. The next Rotator-Plan Solver is for the leftShoulder to the leftForearm. There was a little trick that I learned that allowed me to keep the wrist as FK but move the effector from the forearm to the wrist joint.

Fig 3: Hypergraph of the IK Handle 

I selected the IK Handle on the forearm joint and clicked on the Hypergraph window that showed me the IK Handle selected as well as three other boxes (Fig 3). The one with the greyed out writing is the the effector of the IK Handle. Clicking on that, press W for the move tool and then hit Insert will move let you move the effector - which should allow you to move the effector to the wrist joint (Fig 4).

Fig 4: The effector now moved to it's new location; the wrist.

That's it for this post, next will be a relaivately big post talking about the final controls for the arm and an attempt of an IK/FK switch.