February 23, 2011 AT 4:17 pm

Moar Stochastic Robots

This video is both convoluted and funny (all those bots running into each other), but it demonstrates a cool idea. The purpose of the experiment is to quantify the coupling and uncoupling of stochastic robot systems, and create a mathematical model. It’s a neat approach to modeling such a system, and one I haven’t seen before. It also demonstrates, albeit in a simple way, one of my favorite robotics concepts: stochastic assembly. I’ve written about stochastic robots before:

Each of the little blocks represents a piece of “programmable” (or “smart”) matter. Very similar to the way complete DNA exists in every cell of your body, each of these blocks is programmed with the final shape — the ultimate goal of the assembly process. This is where the “robotic” comes in: each block is a robot, or at least a robotic element — it is programmed to perform a certain task (i.e. to assemble into a specific shape).

The blocks are placed in a “stochastic” environment: a tank of water (or air), for example, with random turbulent currents swirling around inside it. The blocks ride these currents into proximity with one another, and if they a) detect an adjacent block in the right orientation and, b) determine it is beneficial to the final construction, they connect to one another to form a subshape.

What I like most about the concept is that it closely mirrors the process of stem cells and DNA to build a final organism. Further, I think that the idea of self-assembly is critical to the future of robotics and technology — think space craft which assemble themselves in orbit, or nano-bots that enter the bloodstream and assemble into a stent or perhaps even a pacemaker. As Evan Ackerman at IEEE Spectrum puts it:

One application for these types of robots might be in the medical field, where building a robot inside someone’s body could prove to be much more effective than building one outside. All you have to do is inject a bunch of little modules into the bloodstream, they’d randomly whirl about and run into each other and grab on where appropriate, and in a little bit you’d have your robot. You could even program the modules not to assemble themselves until they reached a certain place in the body, and while such precision might take a while (or a whole bunch of injections), the potential is there for extremely precise treatments and repairs.

So what’s up with the word “stochastic” — why not just call them “random”?

Well, firstly: in engineering and science, the word stochastic is generally used to imply a non-deterministic system. In a deterministic robot system, for example, a robot would go from A to B to C. In a non-deterministic (stochastic) system, the robot could start at A, and then go to B or C, and from there it could go back to A, or to B or C (depending on the last decision made). The starting point is the same, but the outcome can be different each time. Designing a system for these conditions means that you have to sort of assume all states are possible at once, though the possibility is often weighted by probability.

Secondly, and more importantly: nobody is going to give you a grant to build and study “random robots” — not nearly impressive-sounding enough. :)


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