Although I've no doubt that digital computing will be crucial to the development of intelligent robotics, one of my interests is in the other—often neglected—technologies that will also be vital to making it happen. One of these is mechanics. The video shown here (top) is Domo, one of the latest robots being developed at the MIT Computer Science and Artificial Intelligence Laboratory. As well as incorporating many new ideas, this robot builds on one concept that was developed at the AI lab a decade ago: the idea of compliant limbs.
Matthew Williamson, an earlier PhD student of Rodney Brooks, worked on the arms for Cog in the mid to late 1990s. As you can see in the animated image (middle) this robot saws in what looks like a natural way. This is clever because, unlike the robot arms you see in car manufacturing plant (or on the Honda robot, ASIMO, for that matter), the limbs to not work by calculating exactly where they are supposed to be at every moment. Instead, they have some give (compliance), provided by springs in the arm structure. This not only makes the robots safer because they push back, but also means that the robot need not 'micromanage' it's arm to the degree that it would have to otherwise. It can count on the push/pull of the springs to do some of the work for it.
An even more obvious example of how physics can help is with locomotion. In the late 1990s, Andy Ruina, developed a walking robot with his team at Cornell University. This may not seem very impressive: it's certainly not the first. However, it is completely passive: it has no 'brain' of any kind, it simply walks due to its structure and the laws of physics as you can see in the video (bottom). Essentially, the legs below the knee act as pendula, with the knee itself stoping them from swinging forward. A little potential energy (the slope) is all it needs for a fairly convincing walking gait.
Though the programming side of robotics is often thought to be the more glamourous, getting your hands dirty in the machine shop can make even more of a difference to the efficiency of the machine.
These things are impressive, but the knowledge that variable compliance and passive dynamics are needed to produce robust and energy efficient motion has been around for a long time. Marvin Minsky recently commented that it was already known in the 1970s that you had to make robot arms compliant in order to make them really useful. The Barrett Technology arm is a good example of this, and may lead to robot manipulators which can be produced cheaply, are lightweight and also safe to use in a home or office environment.
Posted by: Bob Mottram | Sunday, 29 July 2007 at 11:01 AM