Axel Trials May Lead To New Mars Vehicle Designs
Engineers from NASA's Jet Propulsion
Laboratory and students at the California Institute of Technology
have designed and tested a versatile, low-mass robot that can
rappel off cliffs, travel nimbly over steep and rocky terrain, and
explore deep craters.
This prototype rover, called Axel, might help future robotic
spacecraft better explore and investigate foreign worlds such as
Mars. On Earth, Axel might assist in search-and-rescue
operations.
"Axel extends our ability to explore terrains that we haven't
been able to explore in the past, such as deep craters with
vertically-sloped promontories," said Axel's principal
investigator, Issa A.D. Nesnas, of JPL's robotics and mobility
section. "Also, because Axel is relatively low-mass, a mission may
carry a number of Axel rovers. That would give us the opportunity
to be more aggressive with the terrain we would explore, while
keeping the overall risk manageable."
The simple design of Axel -- which can also operate upside-down
-- uses only three motors: one to control each of its two wheels
and a third to control a lever. The lever contains a scoop to
gather lunar or planetary material for scientists to study, and it
also adjusts the robot's two stereo cameras, which can tilt 360
degrees.
Axel's cylindrical body has computing and wireless
communications capabilities and an inertial sensor to operate
autonomously. It also sports a tether that Axel can unreel to
descend from a larger lander, rover or anchor point. The rover can
use different wheel types, from large foldable wheels to inflatable
ones, which help the rover tolerate a hard landing and handle rocky
terrain.
Nesnas co-leads the project with Joel Burdick, a mechanical and
bioengineering professor at Caltech, who supervises a handful of
Caltech graduate and undergraduate students working on the rover
system. Last fall, the JPL-Caltech team demonstrated Axel at the
annual Smithsonian Folklife Festival in Washington, which showcased
NASA for the agency's 50th anniversary.
"Collaboration with Caltech has been key to the success of this
project," Nesnas said. "The students contributed significantly to
the design of the tethered Axel. Their creative work enabled us to
analyze, design and build new wheels, sampling tools and software.
The students also played a key role in field-testing this robot.
Without them, we would not have been able to accomplish such goals,
given our limited resources."
JPL began developing Axel in 1999, in partnership with Purdue
University, West Lafayette, IN, and Arkansas Tech University,
Russellville, AR. The Axel project was funded through NASA's
Exploration System Mission Directorate. Caltech manages JPL for
NASA.