FEB Messages

Overview

The feb_msgs package contains custom ROS 2 message definitions used throughout the FEB autonomous racing system. These messages enable communication between perception, SLAM, planning, and control modules.

Message Definitions

ConesCartesian

Represents detected cones in Cartesian coordinates (x, y) relative to the vehicle.

Fields:

Field	Type	Description
header	std_msgs/Header	Timestamp and frame information
x	float64[]	X coordinates of cone positions (meters)
y	float64[]	Y coordinates of cone positions (meters)
color	int8[]	Cone color codes: 1 = yellow, 2 = blue, -1 = unknown
eval_time	float64	Processing/evaluation time (seconds)

Usage:

Published by perception modules (camera, LiDAR) to provide detected cone positions to SLAM and planning.

Topics:

• /camera/cones - Camera-based cone detections

• /lidar/cones - LiDAR-based cone detections

• /perception/cones - Fused perception output

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State

Represents the current vehicle state estimate.

Fields:

Field	Type	Description
header	std_msgs/Header	Timestamp and frame information
x	float64	X position in global frame (meters)
y	float64	Y position in global frame (meters)
velocity	float64	Forward velocity (m/s)
heading	float64	Vehicle heading angle (radians)
theta	float64	Steering angle (radians)
lap_count	uint8	Current lap number

Usage:

Published by SLAM module to provide vehicle state estimate to planning and control modules.

Topics:

• /slam/state - Vehicle state estimate from SLAM

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Map

Represents the track map with separated left and right cone boundaries.

Fields:

Field	Type	Description
header	std_msgs/Header	Timestamp and frame information
left_cones_x	float64[]	X coordinates of left track boundary cones (meters)
left_cones_y	float64[]	Y coordinates of left track boundary cones (meters)
right_cones_x	float64[]	X coordinates of right track boundary cones (meters)
right_cones_y	float64[]	Y coordinates of right track boundary cones (meters)

Usage:

Published by SLAM module after track mapping and cone association. Used by global path planner to generate racing line.

Topics:

• /slam/map - Complete track map with cone boundaries

—

Cones

Represents detected cones in polar coordinates (range, bearing) relative to the vehicle.

Fields:

Field	Type	Description
header	std_msgs/Header	Timestamp and frame information
r	float64[]	Range to each cone (meters)
theta	float64[]	Bearing angle to each cone (radians)
color	int8[]	Cone color codes: 1 = yellow, 2 = blue, -1 = unknown

Usage:

Alternative representation for cone detections when polar coordinates are more natural (e.g., for certain sensor outputs or algorithms).

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FebPath

Represents a planned trajectory with vehicle state variables along the path.

Fields:

Field	Type	Description
header	std_msgs/Header	Timestamp and frame information
x	float64[]	X positions along path (meters)
y	float64[]	Y positions along path (meters)
v	float64[]	Velocity profile along path (m/s)
psi	float64[]	Heading angles along path (radians)
th	float64[]	Steering angles along path (radians)
a	float64[]	Acceleration profile along path (m/s²)
thdot	float64[]	Steering rate along path (rad/s)

Usage:

Published by path planning modules (global/local path planners) and consumed by MPC controller for trajectory tracking.

Topics:

• /global_path/path - Global racing line

• /local_path/path - Local dynamic path

• /mpc/reference_path - Reference trajectory for MPC

—

Message Conventions

Color Codes:

The FEB system uses standardized color codes for cone classification:

• 1 - Yellow cones (typically right side of track)

• 2 - Blue cones (typically left side of track)

• -1 - Unknown/unclassified cones (e.g., LiDAR detections without color)

Coordinate Frames:

• Vehicle Frame (base_footprint): Origin at vehicle center, X forward, Y left

• Global Frame (map): Fixed world frame established by SLAM

• Most messages use the vehicle frame unless specified in the header

Array Correspondence:

For messages with multiple arrays (e.g., ConesCartesian), arrays of the same index correspond to the same object:

# Example: Third cone
cone_x = msg.x[2]
cone_y = msg.y[2]
cone_color = msg.color[2]