All of these are good. Yaw has other associations (I have also heard
it referred to as what you defined as azimuth, for one) that make it
not ideal.
Actually, I think
angle_of_rotation_from_platform_orientation_to_platform_course does
not clarify the sign convention -- as stated, the resulting number is
always positive, at least in one interpretation. Only if you add a
'clockwise_' in front (for example) does it make clear that one
direction of that angle is positive, and the other direction negative.
The term platform_drift_angle (at least, 'drift angle') is pretty well
described in many books and web documents, applying to both ships and
airplanes (and used for other platforms as well). Because it is
shorter and searchable, that would be my choice; the definition can
include the additional information of course.
My own preference on the sign, absent any actual knowledge, is that
positive drift angle means you are drifting in a direction clockwise
(i.e., increased heading) from your orientation. This is somewhat
supported by
http://www.auf.asn.au/navigation/wind.html
I have asked the sailor I know if there is a sign convention for this
term.
(Note also the above link cites the civil air organization ICAO as
preferring 'track' to 'course', as in 'track made good', 'track over
ground', and so forth. Course is more common but I think has slightly
different implications (namely, course describes your intention, but
track reflects your performance; the calculation of actual drift angle
can only be done given what's actually performed). Since we picked
course for another term, up to the powers that be whether we want to
fix it now...
John
On Oct 24, 2008, at 12:14 AM, Jonathan Gregory wrote:
> could we make the standard name self-explanatory as
> difference_between_platform_orientation_and_platform_course
> or
> angle_of_rotation_from_platform_orientation_to_platform_course
> I prefer the latter because it states the sign convention.
On Oct 24, 2008, at 6:43 AM, Bruno PIGUET wrote:
> But in the case described by John, I would rather call
> "platform_drift_angle" the difference between the platform
> orientation
> (which way it's pointing) and the actual direction of travel (track
> made
> good over the ground).
John
--------------
John Graybeal <mailto:graybeal at mbari.org> -- 831-775-1956
Monterey Bay Aquarium Research Institute
Marine Metadata Interoperability Project:
http://marinemetadata.org
Received on Fri Oct 24 2008 - 11:34:55 BST
