Feet sinking below the floor and arm 'shudder'

I’m in the process of learning how to animate characters… in this case a robot. When I animate him using actions his walk cycle isn’t perfect but pretty good. The moment I convert the action to an NLA strip his feet rotate a little more than they should and ‘dip’ below the floor. His feet are such that I pretty much want them to stay flat the whole time and although they are flat in the striking and crossing positions (where there are keyframes) they rotate in between. I assume this is caused by the rotation of other bones but I don’t know how to stop it. :x

From the clip below (3rd angle) you will also see that when moving his arms there is a slight shudder. I have read the stuff about pre-bends and think I have done this but even so his hands still shake slightly.

If I can iron these things out I feel I will be on the brink of making a short animated feature that would really put a smile on my face. Please help!

Robot animation test #1 (WMV - 1MB)

You are more advanced at the character animation than me, so I have no idea what is causing your problem.

However, I wanted to say that I really like that WIP, very nice!!


About the feet going throught the floor, it might be the bezier curve if the IPO. It defaults to trying to create smooth motion with no sudden changes, but you actually want a sudden change here. So try editing the z-IPO and at the points where your foot lands, change the vertex type to free aligned (select vertex and h-key and grab handles).

I hope this helps.

About the arm, it might help if you post a blend or at least a screen shot of your armature. Then people might be able to help.

By the way, it look’s good. I hope you can get those problems sorted out.

it IS the bone’s IPO. go to pose mode, switch some 3D view to IPO-window and select the bone that is causing problems. in the IPO-view, select all curves, hit TAB to enter edit mode of the curves, select ALL vertices (once or twice press A), then SHIFT+S (snap menu) and “horizontal”. thi should iron out unwanted movement around your keys.

repeat the process for all problematic bones.


Thats new to me. Very handy. Thanks for posting that. Much easier than editing each vertex individually.


Thanks for that but it’s still not working how I’d like. I have uploaded another video. The first clip shows him walking with flat feet but this is just an action. When I convert to an NLA strip his feet wobble a bit more than they should. I’ve done the SHIFT-S, Horizontal thing for all leg bones and it’s working fine until I convert to an NLA strip and then it goes wrong.

Here, see what I mean (keep a close eye on the feet):
Action vs NLA problem - WMV 652KB

Unfortunately this thread was about to drop off the front page and into obscurity… So I’ve rescued it with this post!

So far this forum has been awesome and all my questions have been answered, except this one… Is there no-one out there with knowledge of this problem who can spare 5 minutes to help? A series of “NOs” may be enough to convince me to return to the drawing board!

Maybe, if you don’t mind, you could post a blend file.

Then it might be easier for someone with experience (not me) to solve the problem.

I hope you get it solved. If you do, make sure to let us know how you did it.

Okay, good idea! Here it is: Robot_Walk_Test.blend… It’s 915KB.

Be gentle with him!

I hope you get it solved. If you do, make sure to let us know how you did it.
After much deliberating I’ve finally cracked it! My legs were set-up without IKs so I was just bending the individual parts of the legs… I had to ditch this approach and go for an IK chain (as recommened at blenderchar)… I then, as Solmax says, had to do the shift+s horizontal thing on the solvers and it flattened the motion out completely! This forum is the mutts nutts… It hasn’t let me down yet!

Pat on the back everyone!