We’ve seen a bunch of different spherical robots within the past year, so it makes sense that somebody decided to turn one into a toy. Unfortunately, rather that doing something interesting or especially clever, MechRC has just stuck a RC car with big wheels inside a bubble. Not that there’s anything wrong with that, seeing as the robot is supposed to cost all of $40. I’d say that it would be cheaper and easier to do as a DIY project, but it probably wouldn’t be, even if you’d likely get better results (or at least more creative ones). Look for Spheroidz in time for Christmas 2010.

[ MechRC ] VIA [ I4U ]

The nice thing about robots in space is that there’s no gravity, so you don’t have to worry about things like weight and balance. The annoying thing about robots is space is that there’s no gravity, so orientation and control is a problem. MIT has had a set of robots called SPHERES (Synchronized Position Hold, Engage, Reorient Experimental Satellites) on board the International Space Station since May of 2006 to test out algorithms for autonomous navigation and docking maneuvers. Each sphere is about 8″ in diameter and has 18 sides. They gets around with 12 thrusters powered by compressed CO2, while ultrasonic and infrared sensors and a wireless link tell them where they are. SPHERES are able to maneuver precisely enough to dance around in a circle on the ISS; watch as a third robot enters the pattern:

The idea behind SPHERES is that a bunch of small satellites working together is much cheaper, much more efficient, and much more robust than one single large satellite. It’s swarm robotics, up in space.

[ NASA ] and [ MIT Spheres ] VIA [ Danger Room ]

Spherical robots are nifty designs, and they have several advantages over their wheeled counterparts: they adapt well to all kids of terrain (even water) and are completely sealed, making them ideal for planetary exploration. The big sticking point (as it were) of spherical robots is that they tend to get hung up on obstacles. They move by changing their center of gravity, but they can’t shift their internal mass outside of their own diameter, which means that they have a finite amount of leverage to play with and therefore can’t get themselves over obstacles of a given height, no matter how much power their motors might output.

Greg Schroll, a graduate student at Colorado State, has developed a spherical robot that uses gyroscopes instead of a movable mass for both drive power and steering. The gyros just have to sit there, and depending on which way they’re being spun, they exert torque on the robot to move it forward or turn it. The big advantage to this is that the torque exerted by the gyros increases as they spin faster, meaning that more powerful motor does increase the power of the robot, giving it the ability to literally jump out of holes:

Greg has been named one of Popular Science’s 10 Most Brilliant Innovators of 2009 for his work on this robot (among other things, like those badass air cannons in the video).

[ Popular Science ]

This may not look like the most promising design for a robot, but there’s a lot of potential to be had with robots that can change their shape. These robots, from Ritsumeikan University in Japan, are constructed with spherical shells of spring steel attached to an inner core (which contains the power source and electronics) via shape memory alloy wires. Applying voltage to the wires causes them to contract, deforming the shape of the robot. By doing this, the robot can change its center of gravity to roll in any direction, and by contracting the spring steel enough, the robot stores up enough energy to jump.

The big limitation at the moment is that shape memory alloys only really work in one direction: applying a voltage heats the wire, causing it to shrink, but in order for the wire to unshrink, it has to radiate that same amount of heat, which takes a little while… So the robot can deform to roll or jump, but after it does, it needs a cool-down period.

Even with this (surely surmountable) limitation, jumping robots have an advantage over both ground and flying robots: they can move around without respect to terrain without having to expend energy staying airborn. ‘Course, they’re not as efficient as a ground robot, or as versatile as a flying robot, but they’d be perfect for things like planetary exploration where reliability and versatile mobility are more important than speed.

More info is available in this paper (*.PDF).

[ Ritsumeikan University ]