8. Central Configuration¶

The stack uses one editable runtime file for autonomous behavior tuning:

src/jetracer_bringup/config/main_config.yaml

This file is loaded by bringup launches and applied to multiple nodes (lane following, YOLO, semantic behavior, collision assurance, steering conversion, foxglove bridge, and multipoint navigation).

Why this file exists¶

Keep tunables out of source code.
Avoid drifting values across multiple launch files.
Make field tuning fast and repeatable.

Covered Node Sections¶

main_config.yaml includes:

lane_following
yolo_detection
semantic_behavior
collision_assurance
cmd_vel_to_steering
foxglove_bridge
multipoint_navigation
voice_commander

Each block uses the ROS 2 standard structure:

node_name:
  ros__parameters:
    param_name: value

Lane-Following Controller Selection¶

The lane-following node now supports two lateral controllers selected by:

lane_following.ros__parameters.lateral_controller_type

Valid values:

stanley
mpc

When stanley is selected, tuning uses:

gain_constant: Proportional steering gain (higher = more aggressive turn).
steering_smoothing: First-order output smoothing in [0, 1].
controller_lookahead_m: Forward lookahead distance in the BEV vehicle frame.
controller_heading_points: Number of local waypoints used to estimate path heading.

Detection & Geometry Tuning¶

The BEV pipeline uses these critical parameters to filter the track environment:

luminance_threshold: Drops dark pixels (0-255). Set to 180.0 for white tape on black ground.
roi_top_y: The horizon cut depth.
roi_top_width: The width of the road trapezoid at the horizon.
camera_info_topic: CameraInfo topic used to rectify frames before BEV projection.
use_camera_calibration: Enable or bypass runtime undistortion.
fallback_lane_width_px: Prior lane width used for one-sided fallback.
lane_width_ema_alpha: Smoothing factor for the tracked lane-width estimate.
lane_width_min_px / lane_width_max_px: Plausibility bounds for BEV lane width.
bev_vehicle_center_x_px: Pixel column treated as the vehicle center in BEV.
bev_vehicle_origin_y_px: Pixel row treated as the vehicle origin in BEV.
bev_lateral_m_per_px: Lateral BEV scale in meters per pixel.
bev_forward_m_per_px: Forward BEV scale in meters per pixel.
speed_curvature_gain: Curvature-to-speed falloff gain.
speed_confidence_floor: Minimum speed scaling applied under weak tracking.

When mpc is selected, tuning uses:

mpc_horizon
mpc_dt
mpc_wheelbase
mpc_q_cte
mpc_q_heading
mpc_q_terminal
mpc_r_steer: Steering action cost.
mpc_r_steer_rate: Change-in-steering cost.
mpc_min_speed_ms: Floor speed for matrix stability.
max_steering_rate_radps: Hard per-step steering-rate clamp applied after the solve.

Command interface outputs:

drive_lane: primary ackermann_msgs/AckermannDriveStamped command.
cmd_vel_lane: legacy steering-angle Twist kept for the existing twist_mux path.

Example:

lane_following:
  ros__parameters:
    lateral_controller_type: "mpc"
    mpc_horizon: 8
    mpc_dt: 0.1
    mpc_q_cte: 2.5
    mpc_q_heading: 1.5
    controller_lookahead_m: 0.35
    bev_forward_m_per_px: 0.0030

How to use it¶

Edit values in src/jetracer_bringup/config/main_config.yaml.
Launch normally (bringup launch files default to this config).
Restart the relevant launch or node to apply changes.

Launch override¶

All top-level bringup launch files accept:

config_file:=<path-to-yaml>