In this idea we build a bunch of little modules that consist of basically a AA battery, one or two fast linear actuators, a chip, and some sensors.

Then you can link these all together using dumb hubs between actuators to build a little ball. This could then hopefully move around using the same properties as the collapsing donkey toys.

When the actuators are fully extended, the linkage between the hub and the module is loose and flexible, but when the actuator retracts the linkage becomes tight and stiff.

At this point the actuators at the front should be able to loosen, which will cause the front to collapse. Then the ones just under the back, currently against the ground, should be able to tighten which would cause the whole thing to pitch forward a bit.

If done repeatedly in this way it should be capable of rolling in any direction.

It's also possible, depending on the strength of the actuators and the weight of the modules that the ball could hop a bit by collapsing all of their nodes in preparation, followed by a cascading tightening causing it to suddenly regain ball shape.

It would also be able to, I think, remain tight while it's falling, but as it hits the ground collapse the bottom ones, followed by the next up, followed by the next as a way of absorbing impact on landing.

Rolling up hills might be tricky, dunno yet. If the back sorta hopped a bit and more of the front collapsed maybe it'd work.

It should also be able to collapse the front as a means of braking.

As a last thing, if you put a bunch of cameras into the dumb nodes, recessed a bit so the lens didn't take a beating from rolling around, I wonder if you could capture an interesting image with 30 independent cameras...