New package: saltybot_mode_switch
mode_logic.py (pure, no ROS2 dep — 72/72 tests pass):
State machine: RC → RAMP_TO_AUTO → AUTO → RAMP_TO_RC → RC
• CH6 (axes[5] > 0.5) requests AUTO; CH6 low → RAMP_TO_RC
• Stick >10% in AUTO/RAMP_TO_AUTO/RAMP_TO_RC → instant RC (no ramp)
• Sticks neutral ≥ 2 s after override → override cleared → RAMP_TO_AUTO
• RC link lost (Joy silent > 0.5 s) → instant RC from any state
• SLAM fix lost → RAMP_TO_RC (graceful exit from AUTO)
• No AUTO entry without slam_ok AND rc_link_ok
blend_alpha: 0.0 (RC) → linear ramp over 500 ms → 1.0 (AUTO)
led_pattern: solid_yellow(RC) | blink_green_slow(ramp) |
solid_green(AUTO) | blink_orange_fast(slam lost) |
blink_red_fast(RC link lost)
mode_switch_node.py (ROS2, 20 Hz):
Sub: /rc/joy (Joy), /saltybot/balance_state (String),
/slam_toolbox/pose_with_covariance_stamped (PoseWithCovarianceStamped)
Pub: /saltybot/control_mode (String JSON: mode+blend_alpha+slam_ok+rc_link_ok+override_active)
/saltybot/led_pattern (String)
cmd_vel_mux_node.py (ROS2, 20 Hz):
Sub: /cmd_vel_auto (Twist from Nav2/follower), /saltybot/control_mode
Pub: /cmd_vel (Twist to bridge, scaled by blend_alpha)
Note: remap Nav2/follower output to /cmd_vel_auto in launch.
Tests: 72/72 pass (no ROS2 runtime required).
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.