Projects LIDAR clusters into the D435i depth image to estimate 3-D
obstacle width and height in metres.
- saltybot_scene_msgs/msg/ObstacleSize.msg — new message
- saltybot_scene_msgs/msg/ObstacleSizeArray.msg — array wrapper
- saltybot_scene_msgs/CMakeLists.txt — register new msgs
- saltybot_bringup/_obstacle_size.py — pure-Python helper:
CameraParams (intrinsics + LIDAR→camera extrinsics)
ObstacleSizeEstimate (NamedTuple)
lidar_to_camera() LIDAR frame → camera frame transform
project_to_pixel() pinhole projection + bounds check
sample_depth_median() uint16 depth image window → median metres
estimate_height() vertical strip scan for row extent → height_m
estimate_cluster_size() full pipeline: cluster → size estimate
- saltybot_bringup/obstacle_size_node.py — ROS2 node
sub: /scan, /camera/depth/image_rect_raw, /camera/depth/camera_info
pub: /saltybot/obstacle_sizes (ObstacleSizeArray)
width from LIDAR bbox; height from depth strip back-projection;
graceful fallback (LIDAR-only) when depth image unavailable;
intrinsics latched from CameraInfo on first arrival
- test/test_obstacle_size.py — 33 tests, 33 passing
- setup.py — add obstacle_size entry
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
Jetson Nano — AI/SLAM Platform Setup
Self-balancing robot: Jetson Nano dev environment for ROS2 Humble + SLAM stack.
Stack
| Component | Version / Part |
|---|---|
| Platform | Jetson Nano 4GB |
| JetPack | 4.6 (L4T R32.6.1, CUDA 10.2) |
| ROS2 | Humble Hawksbill |
| DDS | CycloneDDS |
| SLAM | slam_toolbox |
| Nav | Nav2 |
| Depth camera | Intel RealSense D435i |
| LiDAR | RPLIDAR A1M8 |
| MCU bridge | STM32F722 (USB CDC @ 921600) |
Quick Start
# 1. Host setup (once, on fresh JetPack 4.6)
sudo bash scripts/setup-jetson.sh
# 2. Build Docker image
bash scripts/build-and-run.sh build
# 3. Start full stack
bash scripts/build-and-run.sh up
# 4. Open ROS2 shell
bash scripts/build-and-run.sh shell
Docs
docs/pinout.md— GPIO/I2C/UART pinout for all peripheralsdocs/power-budget.md— 10W power envelope analysis
Files
jetson/
├── Dockerfile # L4T base + ROS2 Humble + SLAM packages
├── docker-compose.yml # Multi-service stack (ROS2, RPLIDAR, D435i, STM32)
├── README.md # This file
├── docs/
│ ├── pinout.md # GPIO/I2C/UART pinout reference
│ └── power-budget.md # Power budget analysis (10W envelope)
└── scripts/
├── entrypoint.sh # Docker container entrypoint
├── setup-jetson.sh # Host setup (udev, Docker, nvpmodel)
└── build-and-run.sh # Build/run helper
Power Budget (Summary)
| Scenario | Total |
|---|---|
| Idle | 2.9W |
| Nominal (SLAM active) | ~10.2W |
| Peak | 15.4W |
Target: 10W (MAXN nvpmodel). Use RPLIDAR standby + 640p D435i for compliance.
See docs/power-budget.md for full analysis.