sl-perception
c68b751590
Add saltybot_head_tracking — ROS2 Python node for automatic person-
following using dual-axis PID control targeting the pan/tilt camera head.
Pipeline:
1. Subscribe to /saltybot/objects (DetectedObjectArray from YOLOv8n)
2. Filter for class_id==0 (person); select best target by score:
score = 0.6 * 1/(1+dist_m) + 0.4 * confidence
(falls back to confidence-only when distance_m==0 / unknown)
3. Compute pixel error of bbox centre from image centre
4. Apply dead-zone (10 px default) to suppress micro-jitter
5. Convert pixel error to angle error via camera FOV
6. Independent PID controllers for pan and tilt axes
7. Accumulate PID output into absolute angle setpoint
8. Publish geometry_msgs/Point to /saltybot/gimbal/cmd:
x = pan_angle_deg, y = tilt_angle_deg, z = confidence
State machine:
IDLE -> waiting for first detection
TRACKING -> active PID
LOST -> hold last angle for hold_duration_s (3 s)
CENTERING -> return to (0, 0) at 20 deg/s -> IDLE
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.