Created: July 27 2011


A rag doll that doesn't flop around needs a better name, wouldn't you agree? If it moves with motors we could call it a motor-doll maybe... anyway continuing on from the robot arm simulation, I made a side-view rag motor-doll and set up the joints with some keyframes in a similar way to get a crude animation going.

Now that the structure is not grounded, it becomes quite difficult to keep it still, and I can tell that friction of the feet on the ground is going to be an issue - too little makes it hard to move intentionally, and too much means the joints will never get where they want to be and stepping is unnaturally grabby. Additionally, for the movements I'm trying to reproduce joints will probably need to have different speeds to each other, different speeds depending on what kind of action is being performed, and even different max torques depending on whats happening, especially the ankles. Then there's the question of how to get the legs to react when a tipping over is detected. Sheeshh. I can smell a whoooole lotta tweaking coming up...

Here is a quick video of what I have so far. I am using the keyboard to switch the target keyframe, of which there are only three at the moment. The leg joints have the same target angle in all keyframes, so they're not really doing anything but even so it does a reasonable job of righting itself as long as it's not tipped too far over. Ironically all the unstable jiggling around looks quite appropriate for this scenario.

Can you see where I'm going with this? :~)