sl-perception a9717cd602 feat(scene): semantic scene understanding — YOLOv8n TRT + room classification + hazards (Issue #141)
New packages:
  saltybot_scene_msgs — 4 msgs (SceneObject, SceneObjectArray, RoomClassification, BehaviorHint)
  saltybot_scene      — 3 nodes + launch + config + TRT build script

Nodes:
  scene_detector_node   — YOLOv8-nano TRT FP16 (target ≥15 FPS @ 640×640);
                          synchronized RGB+depth input; filters scene classes
                          (chairs, tables, doors, stairs, pets, appliances);
                          3D back-projection via aligned depth; depth-based hazard
                          scan (HazardClassifier); room classification at 2Hz;
                          publishes /social/scene/objects + /social/scene/hazards
                          + /social/scene/room_type
  behavior_adapter_node — adapts speed_limit_mps + personality_mode from room
                          type and hazard severity; publishes BehaviorHint on
                          /social/scene/behavior_hint (on-change + 1Hz heartbeat)
  costmap_publisher_node — converts SceneObjectArray → PointCloud2 disc rings
                           for Nav2 obstacle_layer + MarkerArray for RViz;
                           publishes /social/scene/obstacle_cloud

Modules:
  yolo_utils.py        — YOLOv8 preprocess/postprocess (letterbox, cx/cy/w/h decode,
                         NMS), COCO+custom class table (door=80, stairs=81, wet=82),
                         hazard-by-class mapping
  room_classifier.py   — rule-based (object co-occurrence weights + softmax) with
                         optional MobileNetV2 TRT/ONNX backend (Places365-style 8-class)
  hazard_classifier.py — depth-only hazard patterns: drop (row-mean cliff), stairs
                         (alternating depth bands), wet floor (depth std-dev), glass
                         (zero depth + strong Sobel edges in RGB)

scripts/build_scene_trt.py — export YOLOv8n → ONNX → TRT FP16; optionally build
                             MobileNetV2 room classifier engine; includes benchmark

Topic map:
  /social/scene/objects          SceneObjectArray  ~15+ FPS
  /social/scene/room_type        RoomClassification ~2 Hz
  /social/scene/hazards          SceneObjectArray  on hazard
  /social/scene/behavior_hint    BehaviorHint      on-change + 1 Hz
  /social/scene/obstacle_cloud   PointCloud2       Nav2 obstacle_layer
  /social/scene/object_markers   MarkerArray       RViz debug

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
2026-03-02 09:59:53 -05:00
..

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

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.