`acoustic-anomaly-wind-turbine`

:::warning [UNTESTED] — v0.6 paper-correct The three DSP cores (acoustic_features, rotor_speed, bpf_modulation) are host-unit-tested on native_sim/native/64; the full app runs end-to-end on native_sim with synthetic acoustics + a canned RPM track. No model ships (stub + deterministic fallback). HiL on a real nacelle with a customer-trained model is bench-gated. :::

Nacelle acoustic condition monitor for wind turbines: a PDM MEMS mic captures audible-band sound, DSP extracts spectral features, blade-periodic energy is normalised to rotor order (RPM-invariant via the blade-pass frequency), and a per-interval anomaly score + advisory subsystem/flag is emitted for both drivetrain tonal faults and gross blade aero-anomalies.

Source: examples/audio/acoustic-anomaly-wind-turbine/.

Honest scope

An airborne nacelle mic credibly detects drivetrain/gearbox/bearing tonals (loudest, most reliable), rotor imbalance (amplitude modulation at the blade-pass frequency), trailing-edge-crack whistle, severe leading-edge erosion, and icing. It does not detect early internal cracks / delamination / fiber breakage — those are Acoustic Emission (ultrasonic, structure-borne, requiring a contact piezo bonded to the blade) and out of scope for an airborne mic.

Blade-pass frequency invariant: BPF = N_blades × RPM / 60 (≈0.75 Hz for a 3-blade turbine at 15 rpm). Evaluating modulation in rotor orders at the current BPF makes the signature RPM-invariant under variable-speed operation.

Pipeline

PDM mic (<alp/audio.h>) --frame--> acoustic_features (FFT bands, flatness,
  centroid, kurtosis) --band energy--> bpf_modulation (Goertzel at BPF orders)
tacho GPIO / tacholess --> rotor_speed --> rpm, BPF
  --> <alp/inference.h> anomaly score (deterministic fallback) --> WTAC record

`board.yaml`

som:
  sku: E1M-AEN701

preset: e1m-evk
cores:
  a32_cluster:
    os: "off"
  m55_he:
    app: ./src
    libraries:
      - tflite_micro
    inference:
      default_arena_kib: 64
    peripherals:
      - gpio                 # tacho pulse input (rotor speed)

diagnostics:
  log_level: info

PDM mic input is the Zephyr DMIC audio subsystem (via CONFIG_AUDIO_DMIC=y), not a peripheral enum. Flip som.sku to E1M-V2M101 for the DEEPX DX-M1 path.

Expected output

# WTAC,t_s,rpm,bpf_hz,anomaly_score,dominant_subsystem,top_band_hz,flags,rpm_src
WTAC,12.0,17.4,0.87,0.62,BLADE_BPF,3333.3,IMBALANCE,ESTIMATED

rpm_src ∈ {TACHO, ESTIMATED, CANNED}: TACHO = live GPIO pulse counting, ESTIMATED = tacholess envelope-based estimate (demo default when the estimate converges), CANNED = fixed look-up table fallback.

Honest scope​

Pipeline​

board.yaml​

Expected output​

See also​

Honest scope

Pipeline

`board.yaml`

Expected output

See also