 alro65
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295efa2d83
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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>
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2026-05-18 15:27:45 -04:00 |
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