The Denning Mobile Robot Company of
Boston was the first company to
offer ready-made autonomous robots that were subsequently purchased
primarily by researchers. Grinnell More's Real World Interface, Inc.
(RWI) and James Slater's Nomadic Technologies (US), along with
Francesco Mondada's K-Team (Switzerland), were other pioneering
companies in this field, addressing the need for ready-made robots for
use by robotics researchers. RWI created the B-21, Nomadic the XR4000,
whilst the tiny
Khepera mobile robot
Khepera mobile robot emerged from the stables of the
Swiss K-Team. However, the high price of these machines meant that
only a few graduate students and military researchers could afford
them. Eventually, the low-cost Pioneer robot was introduced in 1995
(from a collaboration between RWI and ActivMedia Robotics), a project
that expanded research in mobile robotics due to the affordable price.
2 Autonomous navigation techniques
2.1 Indoor operation
2.2 Outdoor operation
By 1999, the Denning company was defunct. In 1998, RWI joined with
ISRobotics to form iRobot. More introduced the
PackBot remote control
robot, veering away from autonomous research robots to pursue military
markets. Nomadic Technologies also left the field. MobileRobots Inc
and K-Team continued to supply the research community.
In 2003 the Defense Advanced Research Projects Agency (DARPA)
contracted with Segway to convert fifteen Segway PTs into Segway
Robotic Mobility Platforms. Segway and delivered units to
April. In June
DARPA worked with
SPAWAR Systems Center San Diego
SPAWAR Systems Center San Diego to
distribute the units to 14 government and university research
Autonomous navigation techniques
An ActivMedia Pioneer 3-AT robot at the Georgia Institute of
Research robots improved in autonomous indoor operation during the
1990s and the 2000s. Ready-made research bases offer the necessary
sensing, mobility and computational power. These include the Pioneer,
PatrolBot, PowerBot, and PeopleBot. These platforms can map buildings
and navigate out-of-the-box, using SLAM and a variation on Monte Carlo
method/Markov localization and modified value-iterated search, with
any sensor of the 2-D range-finder class. This method creates a human
readable map of the robot's workspace that can control and track
robots as they move.
Evolution Robotics offers single-camera VSLAM
software, which replaces range-finding with visual pattern-matching,
but this system cannot create a human-readable map. Other groups are
building stereocam-based VSLAM. Because the stereo camera provides
range-finding data, maps can be made and robots tracked. The K-Team
Khepera, Segway-based platforms and other research robots can link to
external computing resources to use such software.
Precision depends upon sensor precision, data granularity and
calculation speed. Range-finding lasers may have +/-1 cm accuracy
while digital stereo camera accuracy is limited to .25 pixel and thus
is range-dependent. Vision-based systems require more computational
resources than simple range-finding systems such as lasers, but may
employ a digital signal processor embedded with the camera.
Cost/precision trade-offs led to less expensive vision-based systems
on consumer robots while commercial and industrial robots and
automated guided vehicles (AGVs) tend to use laser-based systems.
Outdoors, localization is primarily handled with GPS, however,
satellite signals can frequently be lost due to obstructions. Without
a robots typically use dead reckoning and inertial motion tracking.
Dead reckoning relies on relative wheel motion and is subject to
cumulative slippage errors. Inertial motion tracking uses rate
gyroscopes and accelerometers to measure motion. Accuracy depends upon
sensor quality and calibration. The Segway RMP 400 and Seekur robots
are two of the platforms designed for such research; most other
outdoor research robots are jerry-rigged from existing vehicles.
In constrained outdoor areas, some robots, such as the John Deere
Gator, simply surround the perimeter with radio beacons and use simple
triangulation from three or more beacons to localize and navigate.
Beacons are also used indoors by older AGVs in factories.
Much research software for autonomous robots is
Free Software or Open
Source Software, including: Robot Operating System, Carmen from
Carnegie Mellon, Player/Stage/Gazebo from the University of Southern
California and the ARIA APIs from MobileRobots Inc.
URBI with a
Free Software SDK, is used in many universities.
Commercial software includes Webots, which has been developed since
1998 and is licensed by more than 500 universities. It runs on Linux,
Windows and Mac OS X. In June 2006,
Microsoft Research began offering
free beta-test copies of a
Robotics Studio software development kit
with Pioneer robots in simulation for
^ "Archived copy" (PDF). Archived from the original (PDF) on
2009-12-29. Retrieved 2009-11-28.