End-to-end implementation per docs/sprint-2-plan.md.
Builds: pio run -e esp32-dev SUCCESS, RAM 6.8%, Flash 26.8% (351 KB).
Tests: pytest 129/129 green (110 Sprint 1 + 19 Sprint 2).
Python (arautopilot/studio/simulator/):
- rudder_dynamics.py: marine-realistic physical model of a hydraulic
rudder actuator. Defaults tuned so 100 % PWM produces steady-state
v_max ~5 deg/s, matching the brief's "typical 3-6 dps" for a 30 m
yacht. Includes deadband, min-useful PWM snap, port/stbd asymmetry,
end-stops, optional external torque, RunRecorder helper.
- pid_inner.py: pure-Python reference PID. Anti-windup via back-
calculation, setpoint rate limit, setpoint deadband, derivative LPF,
actuator non-linearity compensation. This module is the algorithmic
source of truth; C++ firmware is a line-by-line port.
Firmware (firmware/ar_autopilot_v1/src/pid/):
- pid_inner.h: header-only C++17 controller, byte-equivalent port of
pid_inner.py. Compiles on ESP32 toolchain AND on host g++/clang/MSVC
(no Arduino dependencies) -- ready for native Unity cross-validation
once a host compiler is installed.
- pid_inner_task.{h,cpp}: FreeRTOS task wrapper. 50 Hz on Core 1
(real-time core). Subscribes to TWDT, bleeds integrator during
STANDBY, surfaces telemetry + tunables via the Modbus slave.
Modbus map (regenerated from YAML):
- 6 new INPUT registers (40-45): setpoint, output, error, kp/ki/kd live
- 4 new HOLDING registers (16-19): writable setpoint + kp/ki/kd req
(writes propagate atomically; zero kp rejected as ILLEGAL_DATA_VALUE)
Tests:
- test_rudder_simulator.py: 9 tests (zero-input rest, full deflection,
end-stop saturation, deadband, min-useful snap, asymmetry, recorder
API, invalid dt, end-stop velocity zeroing).
- test_pid_inner_python.py: 10 tests (positive/negative step response,
setpoint deadband holds, anti-windup bounds under saturation,
allowed=false bleeds integrator, actuator deadband + asymmetry
compensation, output saturation, rate limit, disturbance rejection).
NOT in Sprint 2 (intentional per brief sec. 12):
- Outer heading PID, gain scheduling by SOG, ROT feed-forward
(those land in Sprint 3)
- Cross-validation tests via ctypes (need host C++ compiler that
this Windows machine lacks; algorithmic parity enforced by review)
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
AR-Autopilot
Professional marine autopilot for vessels in the 30-40 m range (motor yachts, motor sailboats, fishing vessels, small ferries, coastal patrol boats).
Part of the AR Suite alongside AR-ECDIS, VMS-Sailor, AR-ShipDesign, AR-ElecArrangement, and AR-StabCol. Sold standalone or bundled with AR-ECDIS.
NOT Dynamic Positioning. NOT joystick docking. This is a classic heading-and-track autopilot with intelligent drift compensation, controlling rudder actuators (hydraulic or electric).
Status
Sprint 0 — Foundations (in progress).
This sprint delivers the repository structure, core data model, seed library, and a passing test suite. No functional firmware, Studio GUI, or display yet — those start in Sprint 1.
See docs/AR_Autopilot_brief.md for the complete project brief, scope, and roadmap.
Components
| Component | Tech | Purpose |
|---|---|---|
Studio (arautopilot/studio/) |
Python 3.11 + PySide6 | Project configurator (integrator-side, not shipped to customers). Generates per-vessel .appack packages |
Firmware (firmware/ar_autopilot_v1/) |
C++ on ESP32 via PlatformIO | Real-time PID control, NMEA 2000 + Modbus, safety logic. Runs on the AR-NMEA-IO v1.0 board (shared with VMS-Sailor) |
Display (display/) |
Flutter Desktop (Win + Linux) | Dedicated bridge cockpit-feel touch display with rotary knob input |
Core models (arautopilot/core/) |
Pydantic v2 | Shared data model (vessel config, PID config, actuator config, alarms, modes, knob state) |
Library (arautopilot/library/) |
YAML + JSON | Curated seed: actuator profiles, default tunings per vessel type |
Requirements
- Python 3.11 or newer
- Git
- (Later sprints) PlatformIO, Flutter SDK, WiX Toolset
Quick start (Sprint 0)
# Create venv and install
python -m venv .venv
.\.venv\Scripts\Activate.ps1
python -m pip install -U pip
pip install -e ".[dev]"
# Run tests
pytest
# Run the Sprint 0 demo (creates, saves, reloads a project config)
python examples/sprint0_demo.py
Repository layout
AR-Autopilot/
├── arautopilot/ # Python package (core models, library, studio stubs, tests)
├── firmware/ # ESP32 firmware (Sprint 1+; only pinout.h in Sprint 0)
├── display/ # Flutter dedicated display (Sprint 4+)
├── examples/ # Runnable demos
├── docs/ # Brief + per-sprint design docs
├── installer/ # WiX MSI scripts (later)
└── tools/ # Helper scripts (later)
See docs/architecture.md for a one-page architecture overview.
Sprint roadmap
| Sprint | Focus |
|---|---|
| 0 | Foundations: repo structure, core data model, seed library, tests |
| 1 | Firmware base (I/O, Modbus, NMEA 2000 read, STANDBY mode) |
| 2 | PID inner loop (rudder position control) |
| 3 | PID outer loop + Heading Hold (with ROT feed-forward & gain scheduling) |
| 4 | Studio + basic dedicated display |
| 5 | True Course + Track Keeping (smooth XTE correction) |
| 6 | Safety, alarms, NMEA 2000 publish, VMS alarm consumption |
| 7 | Knob + commissioning + offline auto-tuning |
| 8 | EKF + adaptive tuning + telemetry + VPN |
| 9 | Hardening + integrated testing |
| 10+ | Phase 2 (wind modes for sailboats) and beyond |
Full detail in the brief.
License
Proprietary. All rights reserved. See LICENSE.txt.
Commercial deployment requires a per-vessel license bound to the installation HWID. Contact alro65@gmail.com for licensing.