Update after discussion

Signed-off-by: Erik Jaegervall <[email protected]>

spec/Driver/Driver.vspec

@@ -55,15 +55,9 @@ HeartRate:
 
 HeadPosition:
   type: branch
-  description: The current position of the driver head on vehicle axis according to ISO 8855.
+  description: The current position of the driver head on vehicle axis according to ISO 23150:2023.
 #include HeadPosition.vspec HeadPosition
 
-MidEyePosition:
-  type: branch
-  description: Mid eye position on vehicle axis according to ISO 8855.
-               Mid eye position refers to the center of a line drawn between the center of the drivers eyes.
-#include MidEyePosition.vspec MidEyePosition
-
 MidEyeGaze:
   type: branch
   description: Direction from mid eye position to object driver is looking at

spec/Driver/HeadPosition.vspec

@@ -7,69 +7,84 @@
 # SPDX-License-Identifier: MPL-2.0
 
 # This file intends to provide data related to head position.
-# It uses axis definition from ISO 8855, where origin is at center of (first) rear axle.
-# Definition of "head center" is implementation dependent.
+# Head position in this file refers to mid eye position.
+# Mid eye position refers to the center of a line drawn between the drivers eyes.
+# Absence of an eye does not affect mid eye position, as it shall be calculated as if both eyes were present.
+#
+# Position is given in the vehicle rear-axle coordinate system as defined by ISO 23150:2023 section 3.7.12
+# This coordinate system corresponds to a vehicle coordinate system as defined by ISO 8855:2011 section 2.11
+# with the vehicle reference point at centre of the (first) rear axle.
 #
 # With the definitions given below example values for a regular LHD passenger vehicle
 # could be something like
 #           X = 2000 mm (head position 2 meters in front of rear axle)
 #           Y = 600 mm (head position 60 cm left of vehicle center)
 #           Z = 1000 mm (head position 100 cm above center of rear axis)
 #
+# Head Roll/Pitch/Yaw refers to relationship between head axis system and the vehicle rear-axle coordinate system.
+#
+# Head axis system is defined as follows
+# Head X-axis corresponds to a vector from midway between left and right pre-auricular point and nasion.
+# Head Y-axis corresponds to a vector orthogonal to X going left from the head on the plane defined by left and right
+# pre-auricular point and nasion
+# Head Z-axis corresponds to vector orthogonal to X and Y going upward.
+#
 
 X:
   datatype: int16
   type: sensor
   unit: mm
-  description: Longitudinal position of head center on vehicle X-axis.
-               Axis definitions according to ISO 8855. Origin at center of (first) rear axle.
-               Positive values = forward of rear axle. Negative values = backward of rear axle.
+  description: Longitudinal position of head center measured as mid eye position on X-axis
+               of the vehicle rear-axle coordinate system as defined by ISO 23150:2023 section 3.7.12
+               Mid eye position refers to the center of a line drawn between the center of the drivers eyes.
+               Positive values = forward of (first) rear-axle. Negative values = backward of (first) rear-axle.
 
 Y:
   datatype: int16
   type: sensor
   unit: mm
-  description: Lateral position of head center on vehicle Y-axis.
-               Axis definitions according to ISO 8855. Origin at center of (first) rear axle.
-               Positive values = left of origin. Negative values = right of origin.
+  description: Lateral position of head center measured as mid eye position on X-axis
+               of the vehicle rear-axle coordinate system as defined by ISO 23150:2023 section 3.7.12
+               Mid eye position refers to the center of a line drawn between the center of the drivers eyes.
+               Positive values = left of rear-axle center. Negative values = right of rear-axle center.
 
 Z:
   datatype: int16
   type: sensor
   unit: mm
-  description: Height position of head center on vehicle Z-axis.
-               Axis definitions according to ISO 8855. Origin at center of (first) rear axle.
-               Positive values = above center of rear axle. Negative values = below center of rear axle.
+  description: Height position of head center measured as mid eye position on X-axis
+               of the vehicle rear-axle coordinate system as defined by ISO 23150:2023 section 3.7.12
+               Mid eye position refers to the center of a line drawn between the center of the drivers eyes.
+               Positive values = above center of rear-axle reference point.
+               Negative values = below center of rear-axle reference point.
 
-Roll:
+Yaw:
   datatype: float
   type: sensor
   unit: degrees
   min: -180
   max: 180
-  description: Head roll (right-hand rule) on vehicle X-axis.
-               Axis definitions according to ISO 8855.
+  description: Head yaw angle, measured from the vehicle sprung mass X-axis as defined by ISO 23150:2023
+               to the head X-axis, around the vehicle Z-axis (right-hand rule).
                0 = Head in normal position.
-               Positive values = head leaned to the right. Negative values = head leaned to the left.
+               Positive values = Head turned left. Negative values = Head turned right.
 
 Pitch:
   datatype: float
   type: sensor
   unit: degrees
-  min: -180
-  max: 180
-  description: Head pitch (right-hand rule) on vehicle Y-axis.
-               Axis definitions according to ISO 8855.
+  min: -90
+  max: 90
+  description: Head pitch angle, measured as angle from vehicle sprung mass XY-plane as defined by ISO 23150:2023
+               to the head X-axis.
                0 = Head in normal position.
-               Positive values = head leaning down. Negative values = head leaning up.
-
-Yaw:
+               Positive values = Head leaning up. Negative values = Head leaning down.
+Roll:
   datatype: float
   type: sensor
   unit: degrees
   min: -180
   max: 180
-  description: Head yaw (right-hand rule) on vehicle Z-axis.
-               Axis definitions according to ISO 8855.
+  description: Head roll angle about the head X-axis (right-hand rule).
                0 = Head in normal position.
-               Positive values = head turned left. Negative values = head turned right.
+               Positive values = Head leaning to the right. Negative values = Head leaning to the left.

spec/Driver/MidEyeGaze.vspec

@@ -7,10 +7,12 @@
 # SPDX-License-Identifier: MPL-2.0
 
 # This file intends to provide data related to mid eye gaze.
-# Mid eye position refers to the center of a line drawn between the center of the drivers eyes.
+# Mid eye position refers to the center of a line drawn between the drivers eyes.
+# Absence of an eye does not affect mid eye position, as it shall be calculated as if both eyes were present.
+#
 # Gaze refers to the direction to the object the driver is looking at measured from
 # mid eye position.
-# Axis definitions according to ISO 8855.
+# Axis definitions correspond to the vehicle rear-axle coordinate system as defined by ISO 23150:2023 section 3.7.12
 #
 # Some examples (at long distance from vehicle)
 #            Object in front of vehicle (at far distance) - Azimuth==0, Elevation == 0
@@ -26,8 +28,7 @@ Azimuth:
   unit: degrees
   min: -180
   max: 180
-  description: Mid eye azimuth gaze (right-hand rule) on vehicle Z-axis.
-               Axis definitions according to ISO 8855.
+  description: Mid eye azimuth gaze (right-hand rule) on vehicle sprung mass Z-axis as defined by ISO 23150:2023
                0 = Driver looking forward.
                Positive values = Driver looking at something on the left side of driver.
                Negative values = Driver looking at something on the right side of driver.
@@ -39,8 +40,8 @@ Elevation:
   min: -90
   max: 90
   description: Elevation to observed object measured
-               as angle between vehicle X/Y plane at driver mid eye position and object.
-               Axis definitions according to ISO 8855.
+               as angle between vehicle sprung mass XY-plane as defined by ISO 23150:2023
+               at driver mid eye position and object.
                0 = Driver looking at something at same height as mid eye position.
                Positive values = Driver looking at something above mid eye position.
                Negative values = Driver looking at something below mid eye position.