In a technology first, a team of NASA engineers
demonstrated fully autonomous X-ray navigation in space
— a capability that could revolutionize NASA’s ability in
the future to pilot robotic spacecraft to the far reaches of
the solar system and beyond.
The demonstration — which the team carried out
with an experiment called Station Explorer for X-ray
Timing and Navigation Technology, or SEXTANT —
showed that millisecond pulsars could be used to
accurately determine the location of an object moving at
thousands of miles per hour in space. This is similar to
how the Global Positioning System (GPS) provides
positioning, navigation, and timing services to users on
earth with its constellation of 24 operating
Vijay Kumar’s lab at the University of Pennsylvania
( www.kumarrobotics.org) has been working on using their
GPS-independent quadrotors for transporting payloads, and
they’re doing it collaboratively. The idea is that objects that
are too large or heavy for one quadrotor to move can instead
be moved by multiple quadrotors working together.
Ultimately, they could be the best way to move items around
What’s new here is not the transportation of
objects with multiple quadrotors, but rather doing it
without some kind of external localization system.
Each of these quads is using its own VGA camera and
an IMU, and that’s it; meaning that what you see here
would work just as well inside as well as outside.
While each quadrotor can do a decent job estimating its
position from camera and inertial data alone, that estimation
will gradually drift away from the drone’s true location, getting
worse and worse the farther the drone moves. With two (or
more) quadrotors rigidly connected while transporting an
object, you can combine the location estimates from each
robot to optimize both of their positions, resulting in a much
more accurate estimate that drifts less.
bots IN BRIEF
14 SERVO 03.2018
Researchers are working hard towards
independent autonomy for flying robots, and we've
seen some impressive examples of drones that can
follow paths and avoid obstacles using only onboard
sensing and computing.
The University of Pennsylvania has been doing some
particularly amazing development in this area, and they've
managed to teach a swarm of a dozen 250g quadrotors to
fly in close formation, even though each one is using just
one small camera and a simple IMU. This is probably the
largest swarm of quadrotors that doesn’t rely on motion
capture or GPS.
Each little quadrotor is equipped with a Qualcomm
Snapdragon Flight development board. The board includes
an onboard quad-core computer, a downward facing VGA
camera with 160° field of view, a VGA stereo camera pair,
and a 4K video camera. For these flights, though, the drones
are only using one or two cores of processing power
(running ROS), a simple onboard IMU, and the downward-looking VGA camera.
NICER’s mirror assemblies concentrate X-rays onto silicon detectors to gather data that probes
the interior makeup of neutron stars, including those that appear to flash regularly, called
pulsars. Photo courtesy of NASA's Goddard Space Flight Center/Keith Gendreau.