Difference between revisions of "TrueWind"

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== Sensors ==
 
== Sensors ==
 
=== Heading ===
 
=== Heading ===
* see http://www.navlab.net/Publications/The_Seven_Ways_to_Find_Heading.pdf
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* see also http://www.navlab.net/Publications/The_Seven_Ways_to_Find_Heading.pdf
 
* [https://en.wikipedia.org/wiki/Compass#Magnetic_compass magnetic compass]
 
* [https://en.wikipedia.org/wiki/Compass#Magnetic_compass magnetic compass]
 
** H true = H magnetic + [https://en.wikipedia.org/wiki/Magnetic_declination Magnetic declination]
 
** H true = H magnetic + [https://en.wikipedia.org/wiki/Magnetic_declination Magnetic declination]

Revision as of 09:25, 30 October 2018

calculate True Wind from Apparent Wind

  • AWA Apparent Wind Angle (relative to H) environment.wind.angleApparent
  • H Heading (relative to true north) navigation.headingTrue
    • AWD Apparent Wind Direction (relative to true north) environment.wind.directionTrue
    • AWD = MOD(H+AWA;360)
  • AWS Apparent Wind Speed environment.wind.speedApparent
  • COG Course Over Ground navigation.courseOverGroundTrue
  • SOG Speed Over Ground navigation.speedOverGround
    • TWS True Wind Speed (relative to ground) environment.wind.speedOverGround
    • TWx = SOG * Sin (COG) - AWS * Sin (AWD)
    • TWy = SOG * Cos (COG) - AWS * Cos (AWD)
    • TWS= SQRT (TWx*TWx + TWy*TWy)
    • TWD True Wind Direction (relative to true north) ???
    • TWD = ATAN ( TWx / TWy )
  • STW Speed Trough Water navigation.speedThroughWater
    • DFT Current Drift (speed relative to ground) environment.current.drift
    • DFTx = SOG * Sin (COG) - STW * Sin (H)
    • DFTy = SOG * Cos (COG) - STW * Cos (H)
    • DFT= SQRT (DFTx*DFTx + DFTy*DFTy)
    • SET Current Set (direction relative to true north) environment.current.setTrue
    • SET = ATAN ( DFTx / DFTy )

simplified, assuming H=COG

  • COG Course Over Ground navigation.courseOverGroundTrue
  • SOG Speed Over Ground navigation.speedOverGround
  • AWA Apparent Wind Angle (relative to H) environment.wind.angleApparent
  • AWS Apparent Wind Speed environment.wind.speedApparent
    • AWx = AWS * Cos (AWA)
    • AWy = AWS * Sin (AWA)
    • TWA True Wind Angle (relative to H) environment.wind.angleTrueGround
    • ATAN2(AWy, -SOG + AWx)
    • TWS True Wind Speed (relative to ground) environment.wind.speedOverGround
    • SQRT (POWER(AWy,2) POWER(-SOG + AWx,2))

see also

Sensors

Heading

SOG and COG

  • GPS receiver (simple)

STW

AWS and AWA