autobailout: Add rate based vtol pitch prediction

[akshar-airbound]

• Add rate based vtol pitch prediction and uses the predicted angle to trigger autobailout
  https://app.notion.com/p/airbound/Add-pitch-angle-prediction-in-autobailout-script-38121adf4be9802781d9fe294e987660
• Change parameters AUTOB_BTRN_DLY and AUTOB_PRED_INT
  https://app.notion.com/p/airbound/Find-AUTOB_BTRN_DLY-and-AUTOB_PRED_INT-based-on-log-analysis-38a21adf4be9800599f8d3c818b59510

[greptile-apps]

Greptile Summary

This PR adds rate-based VTOL pitch prediction to the autobailout Lua script — using the pitch PID's actual rate to project pitch 500 ms ahead and trigger autobailout early if the predicted angle would cross the parachute threshold. It also refactors the pitch-monitoring logic into named helper functions, removes two tunable landing-detect debounce parameters (hardcoding them to 1 s), and bumps the firmware version to rc4-fixes.

• New prediction check (is_predicted_vtol_pitch_exceeding_parathreshold) fires autobailout on a single evaluation with no sustained-exceedance guard, unlike the existing is_vtol_pitch_exceeding_limit which requires exceedance for PIT_TOUT ms; a transient spike in the PID rate reading could cause an unintended mode switch.
• AUTOB_DBG_EN default changed from 0 to 1, enabling continuous dataflash logging at ~20 Hz on all production aircraft by default.
• is_vtol_flight is assigned without local on line 325 of the script, creating an implicit module-level global inconsistent with surrounding code style.

Confidence Score: 4/5

Mergeable with care — the C++ changes are mechanical cleanups, but the Lua autobailout script has a no-debounce prediction path that could trigger an unintended QLoiter switch on a single noisy PID rate sample, and debug logging is now always on in production builds.

The C++ side (hardcoding landing debounce to 1 s, removing the two AP_Param fields) is straightforward and low-risk. The Lua changes introduce a new prediction trigger that can fire on a single loop iteration with no duration guard, unlike every other pitch-monitoring check in the script that has a debounce timeout. While the threshold (~105° VTOL) is high enough to avoid most sensor noise, it introduces asymmetric safety logic worth validating in flight. The DBG_EN default-to-1 change will also fill dataflash faster on all deployed vehicles.

autobailout.lua — prediction trigger debounce logic and the DBG_EN default change; quadplane.cpp — check_land_complete disarmed-motor path (covered in a prior review thread).

Important Files Changed

Filename	Overview
libraries/AP_HAL_ChibiOS/hwdef/Pixhawk6C-bdshot/scripts/autobailout.lua	Core logic refactored into helper functions; adds rate-based VTOL pitch prediction for early autobailout; implicit global, missing debounce on prediction path, and DBG_EN default change need attention.
ArduPlane/quadplane.cpp	Removes configurable relax/lower-limit debounce params (hardcodes 1000 ms); check_land_complete now returns false when motors disarmed, blocking QPOS_LAND_COMPLETE transition (flagged in prior review thread).
ArduPlane/quadplane.h	Removes AP_Int16 fields for relax_debounce_ms and lower_limit_extra_ms to match the hardcoded constants in quadplane.cpp.
ArduPlane/version.h	Version string bumped from rc3-fixes to rc4-fixes.
libraries/AP_HAL_ChibiOS/hwdef/Pixhawk6C-bdshot/defaults.parm	Removes Q_LND_LLIM_MS and Q_LND_RELAX_MS default entries to align with their removal from quadplane.cpp.
libraries/AP_Scripting/docs/docs.lua	Adds LuaLS annotations for qp_att_desired, qp_att_actual, qp_angle_rate, and qp_rate_pid_info; return-type annotations use multiple number returns but actual bindings return userdata tables with named fields.

Flowchart

%%{init: {'theme': 'neutral'}}%%
flowchart TD
    A[update loop] --> B[para_deploy]
    B -->|trigger_para_script| C[return early]
    B -->|no trigger| D{autobailout enabled?}
    D -->|no| C
    D -->|yes| E[get current_mode / actual_vtol_pitch_deg / actual_vtol_pitch_rate]
    E --> F[is_vtol_flight = in_vtol_flight]
    F --> G{autobailout_active?}
    G -->|no| H{is_vtol_pitch_exceeding_limit? pitch_timeout debounce}
    H -->|yes| I[trigger_autobailout set QLOITER]
    H -->|no| J{is_predicted_vtol_pitch_exceeding_parathreshold? NO debounce}
    J -->|yes| I
    J -->|no| K[continue monitoring]
    G -->|yes RECOVERY| L{current_mode == QLOITER?}
    L -->|no| M[manual override autobailout_active = false]
    L -->|yes| N{enough samples avg_err + peak_ang OK?}
    N -->|yes| O[restore pre_bailout_mode autobailout_active = false]
    N -->|no| P[keep collecting samples]
    style J fill:#ffddaa,stroke:#ff8800
    style I fill:#ffaaaa,stroke:#ff0000

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%%{init: {'theme': 'base', 'themeVariables': {"darkMode": true, "background": "#0d1117", "primaryColor": "#21262d", "primaryTextColor": "#e6edf3", "primaryBorderColor": "#8b949e", "lineColor": "#8b949e", "textColor": "#e6edf3", "edgeLabelBackground": "#161b22", "actorBkg": "#21262d", "actorBorder": "#8b949e", "actorTextColor": "#e6edf3", "actorLineColor": "#8b949e", "signalColor": "#8b949e", "signalTextColor": "#e6edf3", "noteBkgColor": "#373320", "noteBorderColor": "#d4a72c", "noteTextColor": "#f0e6c0", "labelBoxBkgColor": "#21262d", "labelBoxBorderColor": "#8b949e", "labelTextColor": "#e6edf3", "loopTextColor": "#e6edf3", "activationBkgColor": "#30363d", "activationBorderColor": "#8b949e"}}}%%
flowchart TD
    A[update loop] --> B[para_deploy]
    B -->|trigger_para_script| C[return early]
    B -->|no trigger| D{autobailout enabled?}
    D -->|no| C
    D -->|yes| E[get current_mode / actual_vtol_pitch_deg / actual_vtol_pitch_rate]
    E --> F[is_vtol_flight = in_vtol_flight]
    F --> G{autobailout_active?}
    G -->|no| H{is_vtol_pitch_exceeding_limit? pitch_timeout debounce}
    H -->|yes| I[trigger_autobailout set QLOITER]
    H -->|no| J{is_predicted_vtol_pitch_exceeding_parathreshold? NO debounce}
    J -->|yes| I
    J -->|no| K[continue monitoring]
    G -->|yes RECOVERY| L{current_mode == QLOITER?}
    L -->|no| M[manual override autobailout_active = false]
    L -->|yes| N{enough samples avg_err + peak_ang OK?}
    N -->|yes| O[restore pre_bailout_mode autobailout_active = false]
    N -->|no| P[keep collecting samples]
    style J fill:#ffddaa,stroke:#ff8800
    style I fill:#ffaaaa,stroke:#ff0000

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_{Reviews (4): Last reviewed commit: "Fixed gcs print" | Re-trigger Greptile}

[greptile-apps]

Disarmed-motor check now blocks land-complete detection permanently

Previously, if motors disarmed during QPOS_LAND_FINAL (e.g. via the disarm watchdog or a manual kill), the function immediately declared land complete and advanced the state machine. The new code instead returns false, which means execution never reaches the land_detector() call that sets QPOS_LAND_COMPLETE. Because this early return fires on every subsequent call while motors remain disarmed, the state machine is permanently stuck in QPOS_LAND_FINAL — there is no other code path that sets QPOS_LAND_COMPLETE under these conditions. If the intent is to let land_detector() run its normal logic even after disarming, the return false needs to be removed so control falls through to the land_detector() check below.

[greptile-apps]

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