Servo - December 2014

72 SERVO 12.2014

littleBits made rapid circuit prototyping possible. Our pressure plate came together in mere minutes, freeing our hands and minds to concentrate on building our defense robot. So, how would the circuit kit handle being turned into a real robot?

This concern is not meant to detract from the awesomeness of littleBits. Anything that can make electronics accessible and exciting to a wide swath of tinkerers of all experience levels is awesome in our book.

This is merely an observation that could apply to any kit — when you try to apply it to projects outside its comfort zone, it might take a little more work. So, the real question is whether robotics is within littleBits’ comfort zone.

littleBits excels as a circuit building platform. The modules snap together effortlessly, and the range of sensors and outputs mean that there are endless combinations that can meet all of your circuit building needs. Since our last article, numerous new examples of the creativity of littleBits users have been featured on the littleBits website ( littlebits.cc) — pinball contraptions, a combination locked safe, and even a “spinning replicator” that will copy an image sensed with a light sensor and recreate it with a servo-operated pen sketching on a rotating surface.

One of the hallmarks that separate robots from sessile circuits is the attribute of movement. Both robots and mere circuits are often capable of receiving sensory input from their environments and using that input to perform certain functions. Circuits largely deal with that input in a passive way, turning on a light or a buzzer much like our pressure plate circuit. A circuit might culminate in some sort of simple mechanism like a servo that waves around an indicator or lever, but that likely doesn’t rise to the level of what most people imagine a robot to be.

Physical mechanisms are much more central to the popular concept of a robot. Such criteria may likely stem from the first appearance of fictional robots, which predate real world robots by a few decades. As you may already know, the term “robot” was coined by Czech writer, Karel Capek in his play R.U.R. (Rossum’s Universal Robots), published in 1920. The word is derived from the Czech word “robota” which refers to forced labor. Indeed, the robots (or rather roboti, to use Capek’s plural) in the play are used for precisely that, and they look very humanoid.

Real world robots in the sense of an electronic autonomous creation didn’t come around until the late 1940s. Perhaps the first was the “tortoise” created by British neuroscientist, William Grey Walter. The tortoise — so named for its low ground clearance and half-hemispherical shell — was a small three-wheeled device powered by an electric motor that was equipped with some basic sensors for tasks like obstacle avoidance. It wasn’t much like Capek’s roboti, but it does share a crucial characteristic with what we consider a real deal robot: It moved around and completed tasks.

The tortoise’s mechanism was a simple drive train. Could we imbue the littleBits with mechanical movement? Last time with the littleBits, we had done some exploration with what kind of mechanisms were possible with the kit. We made a simple arm with three degrees of freedom that was controlled through buttons and dimmers. So, what about a driving platform like we envisioned for the present defender?

Setting out to build a robotic defender revealed one of the biggest limitations to the basic littleBits kit that could impact the driveability of a robot. littleBits allows you to rapidly prototype like a pro, but the circuits from the basic kit are kind of like a domino show (the technical term for a line of dominoes you knock over — the more you know). They only go in one direction. That’s not to say that you can’t do wonderful elaborate things with them, however.

Just like expert domino topplers, you can create sophisticated branching circuits that can create quite the spectacle, but that could pose an issue for aspiring roboticists. The littleBits kit does include servos and motors, but if your creation can only move forward then it doesn’t seem quite like a true robot. Fortunately, the robot-friendly Arduino module provides an ideal solution. Before we dove into programming, we wanted to get better acquainted with our sources of locomotion.

It's Beginning to Look a Lot Like Robots

In our starter kit, we had a DC motor module and a gaggle of servo modules. The DC motor module is nice and compact, with the signature littleBits magnetic connectors which were colored green to denote an output module.