Tired of walking to the supermarket from his
For balance, Bullet employs an onboard
dorm, 21-year-old MIT computer science and
computer and two sensors: a gyro and an
electrical engineering student Stephan Boyer
accelerometer. The former measures Bullet’s
decided he needed a quicker way to travel.
rotation speed and the latter determines its
“I wanted a personal transporter that could
acceleration due to gravity. Using this data,
get me around campus but be as small and
the computer can detect the angle of the
light and fast as possible,” he says. Five months
unicycle and prevent it from leaning too far
later, Boyer had Bullet, a self-balancing electric
forward or backward.
unicycle that reaches a top speed of 15 miles
“Because Bullet only has one wheel, you
per hour and is the envy of his peers.
still have to balance side to side,” says Boyer,
Boyer built Bullet with $1,000 and endless
who does this by twisting his hips to turn and
ingenuity. After teaching himself welding and
occasionally flailing his arms for stabilization,
some mechanical engineering, he got to work
in the same way a flying squirrel uses its tail.
collecting materials: a basic fork to hold both a
Riding it several miles daily, Boyer became
moped wheel and motor, welded-on pedals to
somewhat of a pro at handling the vehicle,
provide foot support, and a top seat. “I didn’t
but he stresses that it takes both skill and
really plan out the [entire design], so the bat-patience. “My number one rule when riding
tery and electronics are held on with zip ties,”
Bullet is that things in the road are always
he says. Bullet also features a kill switch for
bigger than they appear.”
swift deactivation. He says the design could be
built for $600.
— Laura Kiniry
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