Pr 4631 ported 4575 rc11

[vigneshm-debug]

Version : 4.6.3.1 rc-9 (This version of 4.6.3.1 includes fixes till 4.5.7.5 rc11)

[greptile-apps]

Greptile Summary

This PR ports fixes from 4.5.7.5 rc11 into the 4.6.3.1 branch, covering four major areas: landing detection refactoring (parameterised timeout / disarm watchdog), attitude-control relaxation rework (hysteresis thresholds, LPF factor, per-axis pitch clip), expanded Lua scripting bindings for attitude telemetry, and updated Lua scripts (autobailout overhaul, GPS failover hysteresis).

• Landing detection (quadplane.cpp): land_detector signature changed to use the new LND_DET_TIM parameter (default 200 ms); a disarm-watchdog alert is added to check_land_complete.
• Attitude relaxation (AC_AttitudeControl.cpp): old roll+pitch relaxation replaced with a single-axis pitch-only LPF scheme with high/low hysteresis thresholds and a new PIT_CLIP_MAX hard limit.
• Autobailout (autobailout.lua): complete rewrite to detect pitch exceedance on the VTOL-frame axis using sliding-window statistics and predicted angle, with configurable auto-resume.
• GPS failover (ab_gps_mode.lua): adds VACC hysteresis and Auto-mode VTOL-phase awareness.

Confidence Score: 2/5

Not ready to merge — outstanding issues from prior reviews remain unresolved in the landing-detection timeout path and the AC_AttitudeControl static-local state, both of which directly affect flight safety.

The landing state-machine has two confirmed defects: the 200 ms LND_DET_TIM default (far below the 4–6 s hard-coded values it replaces) can trigger premature land-complete, and the !motors->armed() early return blocks QPOS_LAND_COMPLETE after a manual disarm in LAND_FINAL. The attitude-relaxation rewrite introduces static locals for relaxation_factor_lpf and _att_relax_active that survive disarm/re-arm cycles, causing unexpected pitch suppression at the start of the next flight. These were flagged in prior reviews and have not been addressed by the current commit.

Files Needing Attention: ArduPlane/quadplane.cpp (landing detection timeout and disarm watchdog logic) and libraries/AC_AttitudeControl/AC_AttitudeControl.cpp (static local state persistence across arm cycles)

Important Files Changed

Filename	Overview
ArduPlane/quadplane.cpp	Adds LND_DET_TIM / DARM_WDG_T parameters, refactors land_detector() to be parameterised, adds disarm watchdog in check_land_complete; previously-flagged issues (timeout regression, post-disarm state-machine block) are present.
libraries/AC_AttitudeControl/AC_AttitudeControl.cpp	Attitude-relaxation logic fully replaced with hysteresis + LPF scheme; static locals persist across arm/disarm cycles (previously flagged). Thrust-error branches now consistently use the local ang_vel_body, resolving a previous reviewer concern.
ArduPlane/tailsitter.cpp	Expands PHID log message with extra_elevator and position_pitch_sp fields; HAL_LOGGING_ENABLED guard correctly restored (previous issue addressed). Removes set_tailsitter_back_transition_done call consistent with attitude-control rework.
libraries/AP_Scripting/lua_bindings.cpp	Adds four new Lua C bindings (qp_att_desired, qp_att_actual, qp_angle_rate, qp_rate_pid_info) guarded by ArduPlane + QUADPLANE macros. Slight API inconsistency in lua_get_actual_euler_cd (uses lua_settable instead of lua_setfield), but functionally correct.
libraries/AP_HAL_ChibiOS/hwdef/Pixhawk6C-bdshot/scripts/autobailout.lua	Complete rewrite: sliding-window pitch statistics, VTOL-frame pitch detection using new Lua attitude bindings, configurable auto-resume with attempt limit. is_vtol_flight assigned without local (previously flagged).
libraries/AP_HAL_ChibiOS/hwdef/Pixhawk6C-bdshot/defaults.parm	PTCH_LIM_MIN_DEG and TECS_PITCH_MIN changed from -20° to -5°, significantly restricting FW nose-down authority; RELX_* parameter names updated to match renamed AP_Param entries.

Flowchart

%%{init: {'theme': 'neutral'}}%%
flowchart TD
    A[QPOS_LAND_DESCEND] -->|check_land_final: alt < land_final_alt\nor land_detector fires| B[QPOS_LAND_FINAL]
    B --> C{check_land_complete}
    C -->|!motors armed| D[return false — state stuck]
    C -->|lower_limit_start_ms != 0\n& wdg_start_ms == 0| E[Start DARM_WDG_T watchdog]
    E --> F{elapsed >= wdg_t?}
    F -->|Yes| G[GCS EMERGENCY msg\nreset wdg timer\nNO auto-disarm]
    F -->|No| H{land_detector\nLND_DET_TIM 200ms}
    C --> H
    H -->|height change > detect_alt_change\nor timeout not elapsed| I[return false]
    H -->|Landed| J[QPOS_LAND_COMPLETE\ndisarm]

    style D fill:#ff9999
    style G fill:#ffcc99
    style J fill:#99ff99

Loading

_{Reviews (7): Last reviewed commit: "Version changed to 4.6.3.1-rc9-lte_fixes" | Re-trigger Greptile}

[vigneshm-debug]

@greptile

[vigneshm-debug]

@greptile