COMPACT OUTDOOR MULTIPURPOSE
POSE ASSESSMENT SYSTEM (COMPASS)
 COMPASS aids teleoperation control
by providing a display of a vehicle's coordinates on the Operator Control Unit in vehicle position estimation
applications. COMPASS is available as an off-the-shelf item and has been sold
commercially, as well as to multiple government agencies. COMPASS is
ideal as a teleoperation system driving aid or an autonomous navigation
position estimation subsystem. For this application, COMPASS has already
been purchased, and it is described here to illustrate how it can fit into
the proposed effort.
The COMPASS sensor suite
is an integrated system that provides a continuous update of a robotic
vehicle's position using position and orientation estimation (POSE) sensor.
These sensors are fused into a single best estimate using a proprietary
Kalman filter technique developed by ORI. This POSE estimation sensor suite
is packaged as a “Black Box”, with a single RS-232 or CAN interface to
communicate the pose estimate to the Vehicle
Control Unit.
 Omnitech’s COMPASS system
can be fitted with different types and qualities of sensors to meet the
specific criteria of the application to be solved. When COMPASS is used as an
actual position feedback reference for a closed loop vehicle position servo
application, the parameters are very similar to conventional servo system
applications. Typically there is a trade off between three major factors: accuracy,
vehicle speed, and cost effectiveness. Thus the system can be designed
to optimize one of these parameters, or trade off between two parameters, but
optimizing all three simultaneously is not easy given a fixed level of
funding, and sensor and processing technology.
Based on the top-level
design parameters desired for this applications, ORI uses a suite of sensors
for the COMPASS system that will meet the most difficult specifications. This
approach uses a state-of-the-art GPS system to obtain the primary position
estimate with very high accuracy.
Differential,
Carrier-based GPS specifications:
- 12-channel C/A, 12-channel P
code (L1)
- Full wavelength carrier on L1
- Real-time kinematic
measurements with on-the-fly initialization
- Horizontal accuracy: 20 cm
Circular Error Probability (CEP) RMS with good satellite constellations
- Vertical accuracy: 30 cm RMS
- Cold start to first data: 70
seconds
- Warm start to first data:
<30 seconds>
- 3-axis inertial grade
accelerometers
- 3-axis rate/position
gyroscopes
- 1-axis fluxgate magnetometer
compass
- Odometry from water speed
indicator (pitot tube) for vehicle velocity feedback
- 2-axis inclinometer
These sensors are
combined with an onboard computer, executing an Omnitech proprietary Kalman
filter sensor fusion algorithm to provide a statistically optimal pose
estimate from the sensor suite.
COMPASS Datasheet in PDF format
(426k)
 
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