sl-perception
6592b58f65
Adds a rate-limiting shim between raw /cmd_vel and the drive stack to prevent wheel slip, tipping, and jerky motion from step velocity inputs. Core library — _velocity_ramp.py (pure Python, no ROS2 deps) - VelocityRamp: applies independent accel/decel limits to linear-x and angular-z with configurable max_lin_accel, max_lin_decel, max_ang_accel, max_ang_decel - _ramp_axis(): per-axis rate limiter with correct accel/decel selection (decel when |target| < |current| or sign reversal; accel otherwise) - Emergency stop: step(0.0, 0.0) bypasses ramp → immediate zero output - Asymmetric limits supported (e.g. faster decel than accel) ROS2 node — velocity_ramp_node.py - Subscribes /cmd_vel, publishes /cmd_vel_smooth at configurable rate_hz - Parameters: max_lin_accel (0.5 m/s²), max_lin_decel (0.5 m/s²), max_ang_accel (1.0 rad/s²), max_ang_decel (1.0 rad/s²), rate_hz (50) Tests — test/test_velocity_ramp.py: 50/50 passing - _ramp_axis: accel/decel selection, sign reversal, overshoot prevention - Construction: invalid params raise ValueError, defaults verified - Linear/angular ramp-up: step size, target reached, no overshoot - Deceleration: asymmetric limits, partial decel (non-zero target) - Emergency stop: immediate zero, state cleared, resume from zero - Sign reversal: passes through zero without jumping - Reset: state cleared, next ramp starts from zero - Monotonicity: linear and angular outputs are monotone toward target - Rate accuracy: 50Hz/10Hz step sizes, 100-step convergence verified 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.