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alro65 295efa2d83 sprint-2: PID inner loop + Python rudder simulator
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>
2026-05-18 15:27:45 -04:00
alro65 65860948b4 sprint-1: firmware ESP32 base -- STANDBY + Modbus + NMEA 2000 + watchdog
End-to-end implementation of Sprint 1 per docs/sprint-1-plan.md.

Builds: pio run -e esp32-dev SUCCESS, RAM 6.7%, Flash 26.5% (347 KB).
Tests: pytest 110/110 green; pio test -e native deferred (needs host
       C++ compiler -- none on this Windows machine).

Firmware (firmware/ar_autopilot_v1/):

- platformio.ini: 4 envs (esp32-dev release, esp32-debug, native unity
  tests, check static analysis). NMEA2000-library@4.22, NMEA2000_esp32@
  1.0, eModbus@1.7.4 pinned.
- main.cpp: boot in STANDBY, FreeRTOS task spawn, returns to scheduler.
- system/: ar_log.h facade, task_config.h (priorities/stacks/cores
  central table), heartbeat (1 Hz LED + uptime).
- modes/: STANDBY-only state machine; non-STANDBY rejected.
- hal/: di_do.cpp (5 DI + 10 DO with debounce + last-state cache),
  rudder_sensor.cpp (100 Hz ADC + 5-sample median filter, Core 1),
  rudder_actuator.cpp (DO1/DO2/DO3 with three safety interlocks:
  power-off, STANDBY mode, limit switch).
- safety/: TWDT @ 2 s panic-on-expire; 50 Hz safety task on Core 1
  enforcing DI1 physical disengage button, DI4 external alarm,
  both-limit-switch interlock.
- protocols/modbus_slave.cpp: eModbus RTU server on UART2 @ 38400 8N1,
  slave ID 1. 17 inputs + 19 discretes + 5 holdings + 4 coils. Reads
  pull live telemetry; writes validate range and route to handlers.
- protocols/nmea2000_consumer.cpp: stack open with CAN TX=GPIO3
  RX=GPIO1, subscribed to PGN 127250 (Heading) + PGN 127251 (Rate of
  Turn). 5 s staleness flag built in for Sprint 6 alarm wiring.
- filters/median.h: templated MedianFilter<T,N> (host testable).

Cross-cutting:

- modbus_registers.yaml: single source of truth for the Modbus register
  map. 45 entries.
- tools/gen_modbus_registers.py: YAML -> C++ header + Python module
  generator with --check for drift detection.
- arautopilot/shared/modbus_register_map.py: generated Python mirror,
  imported by Studio + tools.
- arautopilot/tests/test_modbus_register_map.py: 30 tests covering
  schema, address uniqueness, range, spot-checks, and drift detection
  (fails if YAML edited without regenerating).
- firmware/ar_autopilot_v1/tools/modbus_client_test.py: manual Modbus
  client for poking the slave from a PC with USB-RS485 dongle.
- firmware/ar_autopilot_v1/test/test_median_filter/test_median.cpp:
  8 Unity tests of the median filter (host-side, no Arduino dependency).
- docs/firmware.md: full operator + integrator guide (toolchain, build,
  flash, expected boot log, troubleshooting, Sprint 1 capability matrix).

Architecture note: opted for Arduino-on-ESP32 only instead of the
proposed dual Arduino-as-ESP-IDF-component setup. Rationale documented
in CHANGELOG and docs/firmware.md -- Arduino-on-ESP32 already provides
the FreeRTOS primitives we need; dual framework adds fragility without
benefit at Sprint 1 scope. Reconsider in Sprint 8 (OTA + secure boot).

NOT in Sprint 1 (intentional per brief sec. 12):
  - PID loops (inner/outer)
  - True Course / Track Keeping
  - Full alarm catalogue beyond DI1/DI4
  - Knob driver
  - Studio GUI / dedicated display

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
2026-05-18 10:45:56 -04:00