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134 Modern Robotics

Rather, there were clusters, or “clouds,” of features that corresponded
in a rough way to the actual boundaries of the obstacles. While the
Cart usually negotiated cluttered rooms successfully, it sometimes
misread the orientation of an object or got stuck in repeated attempts
to fit itself through a narrow space. The camera system could also fail
to identify objects whose edges lacked sufficient contrast.
When taken outdoors, the Cart faced additional challenges.
Moravec and his fellow researchers discovered that because the
robot moved so slowly, the shadows of objects would move up to
a foot and a half (half a meter) between snapshots. The shadows,
which often had a higher contrast than the edges of objects them-
selves, would then be mistaken for object boundaries.

I WAS THERE: MORAVEC THE HACKER

Projects such as the Stanford Cart (as well as anything involving
images or graphics) required large amounts of computer time.
Unfortunately, the limited amount of computer power (much less
than on a single desktop machine today) had to be shared by many
researchers. Like their counterparts at MIT, the Stanford computer
users would keep strange hours to take advantage of “slack time” on
the machines. The term hacker came to be applied to such users who
developed sophisticated tricks to wring the last byte of useful work
out of the machines.
Moravec went further than even most hackers. By the late 1970s,
he was spending so much time at the computer in the Stanford
Artificial Intelligence Lab (SAIL) that he slept by day in a little cubby-
hole that he had constructed in the building’s rafters, emerging late
at night when the computer system was idle.
When he was online, Moravec arranged to have friends bring him
groceries so he did not have to leave the keyboard to eat. Moravec’s
eccentric behavior was less impressive, though, than the storm of
ideas with which he pelted his colleagues. According to Rodney
Brooks, these included space elevators, huge parallel-processing
computers, and even the transfer of human consciousness into
machines.