sl-controls 5108fa8fa1 feat(controls): Wheel slip detector (Issue #262)
Detect wheel slip by comparing commanded velocity vs actual encoder velocity.
Publishes Bool flag on /saltybot/wheel_slip_detected when slip detected >0.5s.

Features:
- Subscribe to /cmd_vel (commanded) and /odom (actual velocity)
- Compare velocity magnitudes with 0.1 m/s threshold
- Persistence: slip must persist >0.5s to trigger (debounces transients)
- Publish Bool on /saltybot/wheel_slip_detected with detection status
- 10Hz monitoring frequency, configurable parameters

Algorithm:
- Compute linear speed from x,y components
- Calculate velocity difference
- If exceeds threshold: increment slip duration
- If duration > timeout: declare slip detected

Benefits:
- Detects environmental slip (ice, mud, wet surfaces)
- Triggers speed reduction to maintain traction
- Prevents wheel spinning/rut digging
- Safety response for loss of grip

Topics:
- Subscribed: /cmd_vel (Twist), /odom (Odometry)
- Published: /saltybot/wheel_slip_detected (Bool)

Config: frequency=10Hz, slip_threshold=0.1 m/s, slip_timeout=0.5s

Co-Authored-By: Claude Haiku 4.5 <noreply@anthropic.com>
2026-03-02 17:29:03 -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.