Page 155 - Modern Robotics Building Versatile Macines

RADICAL ROBOTICIST 135

Robotic Vehicles

Moravec moved to Carnegie Mellon University (CMU) in Pittsburgh
in 1980 as a research scientist. He was promoted to senior research
scientist in 1985 and principal research scientist in 1993. For his
first project at CMU, Moravec began to develop a successor to the
Stanford Cart: the CMU Rover. Unlike the Stanford Cart, the Rover
carried a dozen or so computer processors on board, although the
heavy-duty image processing was still handled by a minicomputer
on a remote link. In addition to a TV camera, the Rover included
infrared and sonar sensors. The robot was about three feet (1 m)
tall and weighed 198 pounds (90 kg). New image-processing arrays
made picture analysis about a hundred times faster than with the
old Cart.
In 1984, Moravec and his team began a contract to develop
a sonar navigation system for Denning Mobile Robotics. Since
the sonar provided distance information but could not localize
an object within its 30-degree-wide beam, Moravec and gradu-
ate student Alberto Elfes devised a different approach to avoiding
obstacles. A three-dimensional grid around the robot was used to
plot the possibility that an object may exist in a given cell. The
result of successive “pings” generated a sort of probability map,
which was later extended to combine sonar and visual data. Finally,
an algorithm was developed by which the robot could improve its
picture of the world by comparing it to a simulated map. Essentially,
the result of all this processing was that the robot did not try to
avoid obstacles, rather to determine a route that was safely free of
them. By the early 1990s, the availability of new supercomputers
such as the CM-5 “Connection Machine” improved the accuracy of
this grid-based navigation system steadily, and progress continued
through the decade.
Moravec’s Carnegie Mellon lab also worked on a series of self-
driving vehicles. The earliest version, the 1984 Terragator, could roll
along jogging trails at about three feet (1 m) per second. Sometimes,
however, the remote-control computer would confuse a tree trunk
with the road and the Terragator would try to climb it!
Navlab, the first of a new series, begun in 1986, was a big blue
truck full of bulky computer gear. It used algorithms to try to pick