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Lysbilde 1

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Ring laser gyro compass. Experiences from Svalbard and the. importance of secant latitude RMS ... Jan dland used to represent IXSEA. before he joined Aquadyne ... – PowerPoint PPT presentation

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Title: Lysbilde 1


1
Ring laser gyro compassExperiences from Svalbard
and the importance of secant latitude RMS
Havbunnskartlegging og inspeksjon, Geilo 6.2.2008
2
Aquadynes Inertial pallet

3
Aquadyne Bergen
Jan Ådland used to represent IXSEA before he
joined Aquadyne to head our Bergen Office
4
Original sketch by Georges Sagnac
5
(No Transcript)
6
(No Transcript)
7
Mirror
Laser
Detector
8
The sensor is rotating anti-clockwise
9
(No Transcript)
10
Secant latitude RMS
  • 1/cos(x) , x degrees north
  • Multiply by specification (0.10)

11
Local navigation frame-right hand co-ordinate
system
X-axis North Y-axis East Z-axis Nadir
12
RMS heading error with latitude
RMS heading
Spitsbergen
Geilo
Tromsø
Asker
London
latitude
13
IMU 01 and IMU 02 Heading Static at 78N
Individual random walk
degrees
hours
IMU 01 heading
IMU 02 heading
14
Differences between IMU 01 og IMU 02 Heading
Static 78 N
degrees
hours
15
Lodestar IMU 01 and IMU 02 Heading - Dynamic
78N
degrees
hours
IMU 01 Heading IMU 02 Heading
16
Lodestar IMU 01 and IMU 02 Heading Dynamic 78N
degrees
hours
IMU 01 Heading /100 IMU 02 Heading
/100 Difference in Heading
17
Statistical Background to the Analysis Heading
performance figures for inertial sensors are
usually given in terms of RMS or standard
deviation (SD).  
value
sample
18
  • Data Processing Method
  • Long data sets were collected in static and
    dynamic conditions. This data was interpolated,
    re-sampled, differenced and finally the
    statistics computed.
  • The processing steps were as follows.
  • Output from two units recorded on same PC(with
    common time stamp) in Spitsbergen

  • The data series were interpolated
  • The interpolated data was re-sampled using common
    time series
  • One re-sampled data set is now subtracted from
    the other re-sampled data set
  • Statistics computed on the resulting differenced
    data

19
The Variance Sum Law
  • For two normally distributed independent data
    sets X and Y
  • with variance and variance
  • then .
  • This law states that the variance of a data set,
    that represents the differences between two data
    sets X and Y,
  • is the sum of the variance of X and the variance
    of Y.

20
Aquadyne ASSolbråveien 411383
AskerNorwayPhone 47 66 98 71 50
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