LittleDog Navigates Ruff Terrain
Robots are notoriously bad when it comes to the unpredictable. This is unfortunate, since most of the environments on Earth are more or less unpredictable. Professor Stefan Schaal from USC Viterbi is attempting to build a robot dog that can autonomously navigate over very rough terrain, and has received $1.5 million from DARPA’s Learning Locomotion program in order to do so. DARPA is interested because a pack of robot dogs would be great at carrying supplies for troops, as long as they’re capable of keeping up on their own. Currently, they have large dogbots in active development that can handle flats and ramps, but nothing more challenging.
Schaal’s LittleDog is designed more as a software and sensor research platform than to be a hardware prototype for DARPA. LittleDog itself is built by Boston Dynamics, and is fairly complicated. Each of LittleDog’s legs is powered by three electric motors, giving them a lot of flexibility. Sensors measure the angles of each joint as well as body orientation and foot/ground contact. The basic strategy for walking over both smooth and rough terrain is “to adjust a smooth walking pattern generator with the selection of every foot placement such that the center of gravity follows a stable trajectory. To do this, the robot calculates where and how it should proceed, based on the current position, velocity, and acceleration of its legs. If one effort fails, the dog learns from its mistakes and tries another route the next time.”
There are two clips below; the first is an earlier (wired) version of LittleDog dealing with some pretty rocky terrain, and the second clip shows a wireless (and noticeably more evolved) version.