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The outer three LEDs indicate the vehicle pose and are permanently illuminated. The section Pose Calibration describes how the LED positions are related to the reference pose.

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While the IPS is running, the vehicle is placed in various poses on the floor, following a particular calibration sequence. The calibration features `(back_x, back_y, direction_x, direction_y)` are recorded from the running IPS. A linear calibration is then fitted using least squares.

# Coordinate Systems

## IPS Image Coordinates

The image coordinates correspond to the IPS image sensor pixels. They are only relevant for the IPS LED detection.

## Floor Coordinates

MathJax Inline Equation
equation x \in [0, 4.5], y \in [0, 4]

X/Y units: Meter

Origin: corner of the PVC canvas, towards the windows on the right.

Yaw angle: Measured from the x-axis, counterclockwise.

Useful yaw equations:

`direction_x = cos(yaw)direction_y = sin(yaw)yaw = atan2(direction_y, direction_x)`