There are already standard names for the platform speed with respect to
the air (platform_speed_wrt_air) and ground (platform_speed_wrt_ground),
and there are standard names that I think one could use for the
different components of platform's velocity in its own local
coordinates (platform_heave_rate, platform_surge_rate, and
platform_sway_rate).
But, there are not standard names for all three components of the
platform's velocity with respect to the air and ground. For the ground,
one can represent both horizontal coordinates directly with
platform_speed_wrt_ground and platform_course, but there isn't a
standard name for the vertical velocity or the two horizontal components
separately.
So for velocity with respect to the ground, there are two possible
schemes that seem rather reasonable:
1. platform_DIRECTION_velocity
2. platform_DIRECTION_velocity_wrt_ground
where DIRECTION is "northward", "southward", "eastward", "westward",
"downward", or "upward"; or potentially also "x", "y", and "z"..
The first one is shorter and looks more like the standard names for the
components of the wind velocity (northward_wind/southward_wind,
eastward_wind/westward_wind, and downward_air_velocity/upward_air_velocity).
The second one is more consistent with platform_speed_wrt_ground and
also has the natural extension of replacing "_ground" with "_air" to
consider the velocity components with respect to air.
For velocity with respect to air, the second form but with "_ground"
replaced with "_air" would work for the earth frame. For the local
platform frame; DIRECTION could be x, y, z or be something like
fore/aft, port/starboard, and up/down.
Now, there is some duplication if standard names for velocity with
respect to ground and air are added since one could use one set and the
wind velocity standard names to determine the other set (for the
platform local frame, the pitch, roll, and yaw variables would also be
needed). So, one could add just one set and the other would not be
needed at all, though it might still be convenient.
I can see the names for the velocity components with respect to air
being useful for airborne instruments where the instantaneous cross-wind
can be non-negligible compared to the air-speed. This is in fact the
situation I am working with (large tethered balloon that re-orients
slowly). There is already a solution for the horizontal components with
respect to the ground, but there isn't yet one for the vertical component.
Would such additions to the standard names table be useful, or not
useful enough to add? If so, which naming scheme would make the most
sense for it to be descriptive and be consistent with other standard names?
--
Dr. Freja Nordsiek
Max-Planck-Institut für Dynamik und Selbstorganisation
Am Fassberg 17
37077 Göttingen
Deutschland / Germany
[email protected]
+49 551-5176-304 (phone)
+49 551-5176-302 (fax)
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