Coordinates need a frame and units
A conceptual XY view compares a Cartesian position expressed in base_link with a forward displacement along an IK frame rotated ninety degrees. Forward is positive local X, so its direction in the room follows the frame. Distances use metres; task joint angles use degrees while ROS revolute joint states use radians. Illustrative coordinates are not calibrated robot targets.
EROBS / SPATIAL CONVENTIONS
Coordinates need a frame and units
Conceptual XY view. The right-hand frame is rotated 90°; geometry is illustrative.
Absolute position
Relative displacement
+X
+Y
Target
0.30 m
0.20 m
frame_id: "base_link"
Position is measured from this origin.
local +Y
local +X
forward
distance: 0.01
selected IK frame
The local direction rotates with it.
DISTANCE
10 mm = 0.01 m
REVOLUTE JOINT ANGLE
90° = π/2 rad
task pose → ROS arm joint state
These are unit conventions, not calibrated targets. Prismatic joint positions use metres.