A few questions I have.
1. I am trying to set this up with legs, similar to your robot. How did you get the feet to keep the guy in the air?
2. How would you animate these limbs, like you have. I am setting the positions of the "end" objects to image points on a sprite. Are there better ways to do this?
the feet don't keep him up in the air, his waist is animated separately from them with a sine oscillation, and it simply looks like they are
theres literally, A TON of ways to animate them. if what your doing works theres nothing wrong with it, but in my cap it uses alterable bezier paths, which are kind of complicated to set up if you don't know how. for a walking animation, wtv looks good and suits your needs is fine.
the robot also has a special routine to stick feet above the ground, which adds to the walking effect.
i cant really say if theres a "better" way to animate them, my method is cumbersome and confusing in all honesty, and unless you want an adaptable walking pattern theres really no reason for it.
i think the best way for you to do what you want might be adding the ends as bones to some big character object, and simply move them using bone movement and bone movement animations. all the tweening stuff and animation controls are set up for you already.
i cant really say anymore, its all up to your imagination! the purpose of the tutorial is to show you how to make IK arms using my method, and i don't wanna show everyone how i do the animating itself in one single "model", because then a lot of stuff will just end up being a clone of it. i give you tools, you have to build the car/tank/airplane/giant spider robot with your own imagination
anyways, i really think that bone movement ends method would be the easiest/best looking for what your trying to do.