sl-controls bc45208768 feat: Add Issue #194 - Speed limiter node (50Hz safety constraints)
Implements speed limiter ROS2 node that enforces safety constraints from:
  - Terrain type (via /saltybot/terrain_speed_scale)
  - Battery level (via /saltybot/speed_limit)
  - Emergency system state (via /saltybot/emergency)

Node computes minimum scale factor and applies to /cmd_vel, forwarding
limited commands to /saltybot/cmd_vel_limited. Publishes JSON telemetry
on /saltybot/speed_limit_info at 50Hz (20ms cycle).

Features:
  - Subscription to terrain, battery, and emergency constraints
  - Twist velocity scaling with min-of-three constraint logic
  - JSON telemetry with timestamp and all scale factors
  - 50Hz timer-based publishing for real-time control
  - Emergency state mapping (NOMINAL/RECOVERING/STOPPING/ESCALATED)
  - Comprehensive unit tests (18 test cases)

Package: saltybot_speed_limiter
Entry point: speed_limiter_node
Launch file: speed_limiter.launch.py

Co-Authored-By: Claude Haiku 4.5 <noreply@anthropic.com>
2026-03-02 11:14:10 -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.