I think this one could probably have worked had I tweaked it a little more; there's a bit of a kink in the arm when it comes forward on the down position. I tried to have it carry on forward, as in Richard Williams' cycle, but to be honest following his diagram for the arms has always given me issues. I find that the motion is a little too formulaic and robotic-looking. It's a great basis for the keyframes and understanding the principles of the movement, don't get me wrong, but I don't think that having the entire arm continue forward works too well. I think that for best effect only the forearm needs to continue forward - the upper arm could stay mostly still, or even have it start to come back already.
In this attempt I tried to work some slight joint breaking into my key poses, thinking they were as 'key' to block out as the positions of the arms. With the way that Softimage interpolates keyframes, though, it probably wasn't the best idea. The arm wobbles about a bit weirdly - again, with some adjustments it could have worked, but I think it was just a bit too complex at this stage.
Most of the movement came from the shoulder in order to 'break' the joint - looking at the fcurves shows the problem:
They're all bumpy and uneven as Softimage tries to calculate the path of motion. With some manual tweaking to smooth them out it could possibly have worked but I don't really think the poses themselves were strong enough to really warrant the effort. Back to basics.
Looking at this version after a break it doesn't look as bad as I'd initially thought. I should have kept the rear arm stationary - it's a bit distracting - but arguably I think I've sort of hit the key poses for the arm fairly well. I think the only thing is that perhaps it delays too much as it's forward; perhaps I should start moving the upper arm back a little sooner as the forearm continues forward. The weird bump issue with the up and down is still there; I really have no idea what's happened, as all the keyframes are exactly the same. I can only assume that something's gone wrong somewhere with the interpolation.
Even with Richard Williams' diagram I'm finding it very difficult to line the arms up correctly, particularly on the 'down' position. Walk cycles in any medium are difficult but I'm finding the whole thing compounded by Softimage's lack of an onion skin. Continuing the swing forward on the down position is tricky to align without it jerking about weirdly (as seen above) - at one stage I even started looking up some similar 'casual' walk cycles in an attempt to understand how they'd posed the arms on their own rigs and to see how the interpolation was working.
I found some very nice examples:
What's interesting about this one is that nearly all the movement is in the wrists and forearms; the biceps and shoulders don't go very far at all. It's a lovely, subtle movement.
Owing to our limited rig, though, something like the above might not be wholly possible. So I found something a little more 'typical' and similar to the Williams example.
Again, some really lovely overlap and the upper arms don't travel so much. Using the above as a guide I tried to roughly emulate (read: shamelessly copy) the positions to get an idea of where I might be going wrong.
I managed to sort out the issue with the bumping at this stage; somehow, the fcurves got slightly altered on the hip object. I have no idea how but the curve was completely out of whack and had inverted itself; simply altering the slope of the handles to smooth it out fixed the problem.
The arm's pretty similar to V13. I think it's alright, though arguably I don't think I've hit the poses as well as before. The arc of the swing isn't really there - it kind of travels diagonally from its position on the down pose to the reverse contact, so I need to look at sorting that out.
The arm also remains mostly stationary on the down position, not really doing anything at all. As above I need to continue the forearm going up and maybe even start to move the upper arm backwards.
I'm going to mess around with it a little more and see if I can sort that arc out!