link_state: add vector3 linear/angular components

Deprecate the //link_state/velocity and
//link_state/acceleration elements since the `pose`
type is not well-suited to represent vector6 data.
Add pairs of vector3 angular_* and linear_* elements
for velocity and acceleration to replace the pose-typed
elements.

Signed-off-by: Steve Peters <[email protected]>

Migration.md

@@ -638,6 +638,12 @@ ABI was broken for `sdf::Element`, and restored on version 11.2.1.
     + `//joint_state/axis2_state/velocity`
     + `//joint_state/axis2_state/acceleration`
 
+1. **link_state.sdf**:
+    + `//link_state/linear_velocity`
+    + `//link_state/angular_velocity`
+    + `//link_state/linear_acceleration`
+    + `//link_state/angular_acceleration`
+
 ### Modifications
 
 1. **state.sdf**, **model_state.sdf**, **joint_state.sdf**, **link_state.sdf**,
@@ -660,6 +666,12 @@ ABI was broken for `sdf::Element`, and restored on version 11.2.1.
     + `//joint_state/angle` is deprecated in favor of `//axis_state/position`
       and  `//axis2_state/position`.
 
+1. **link_state.sdf**:
+    + `//link_state/velocity` is deprecated in favor of `//link_state/angular_velocity`
+      and  `//link_state/linear_velocity`.
+    + `//link_state/acceleration` is deprecated in favor of `//link_state/angular_acceleration`
+      and  `//link_state/linear_acceleration`.
+
 ## SDFormat specification 1.10 to 1.11
 
 ### Additions

sdf/1.12/link_state.sdf

@@ -6,14 +6,34 @@
     <description>Name of the link</description>
   </attribute>
 
-  <element name="velocity" type="pose" default="0 0 0 0 0 0" required="0">
+  <element name="angular_velocity" type="vector3" default="0 0 0 0 0 0" required="0">
+    <description>Angular velocity of the link relative to the world frame.
+    </description>
+  </element>
+
+  <element name="linear_velocity" type="vector3" default="0 0 0 0 0 0" required="0">
+    <description>Linear velocity of the link relative to the world frame.
+    </description>
+  </element>
+
+  <element name="velocity" type="pose" default="0 0 0 0 0 0" required="-1">
     <description>Velocity of the link. The x, y, z components of the pose
       correspond to the linear velocity of the link, and the roll, pitch, yaw
       components correspond to the angular velocity of the link
     </description>
   </element>
 
-  <element name="acceleration" type="pose" default="0 0 0 0 0 0" required="0">
+  <element name="angular_acceleration" type="vector3" default="0 0 0 0 0 0" required="0">
+    <description>Angular acceleration of the link relative to the world frame.
+    </description>
+  </element>
+
+  <element name="linear_acceleration" type="vector3" default="0 0 0 0 0 0" required="0">
+    <description>Linear acceleration of the link relative to the world frame.
+    </description>
+  </element>
+
+  <element name="acceleration" type="pose" default="0 0 0 0 0 0" required="-1">
     <description>Acceleration of the link. The x, y, z components of the pose
       correspond to the linear acceleration of the link, and the roll,
       pitch, yaw components correspond to the angular acceleration of the link