PX4-Autopilot Main Release Notes

Alpha

This contains changes to the PX4 main branch that are not included in the next release (PX4 v1.18).

WARNING

PX4 v1.18 is in beta testing. Update these notes with features that are going to be in main (PX4 v2.0 or later) but not the PX4 v1.18 release.

Read Before Upgrading

Please continue reading for upgrade instructions.

Major Changes

• Motor failure recovery for hexarotors. On a detected single motor failure the control allocator removes the failed motor and, on a hexarotor, additionally stops (CA_FAILURE_MODE = 1) or reverses (2) the motor opposite it, recovering the yaw authority that is otherwise lost. Reversing keeps the opposite motor in the allocation and needs a reverse-capable ESC; the reverse thrust the allocator expects from a forward propeller is set with CA_REV_THR_FRAC (default 0.4). Disabled by default. (PX4-Autopilot#28078)

Upgrade Guide

• COM_ARM_TRAFF has been replaced by COM_TRAFF_AVOID. The old value 3 ("enforce for mission modes only") is migrated to COM_TRAFF_AVOID=2, which blocks arming in all modes, not just mission modes. If you relied on being able to arm manually with traffic detected, set COM_TRAFF_AVOID=1 (warning only) instead.
• PCA9685_SCHD_HZ has been removed. PCA9685_PWM_FREQ now sets both the PWM frequency of the PCA9685 and the rate at which values are pushed to it; if you had PCA9685_SCHD_HZ set to a non-default value, set PCA9685_PWM_FREQ to it after upgrading. Frequencies above 400 Hz (previously only usable in duty-cycle mode) are no longer supported.
• Re-check motor failure handling on hexarotors. CA_FAILURE_MODE = 1 now also stops the motor opposite the failed one on a hexarotor (previously only the failed motor was removed from the allocation). Other airframes are unaffected, and CA_FAILURE_MODE=0 (the default) is unchanged. See Motor Failure Recovery. (PX4-Autopilot#28078)

Other changes

• Fast mission Return modes (RTL_TYPE = 2 and 4) now skip DO_JUMP commands (loops) while following the mission path. (PX4-Autopilot#26993: fix(navigator): goToNextPositionItem skip loops when required)

Hardware Support

• DroneCAN ESCs no longer need to set UAVCAN_PUB_ARM as ArmingStatus is published automatically whenever UAVCAN_ENABLE is 3 (ESC output enabled). (PX4-Autopilot#28364)

Common

• The unit and functional test suite builds, links and runs on macOS (make tests), and px4_poll() timeouts on macOS wait for their full duration instead of returning at once. The blended GPS timestamp is accumulated in double and rounded once instead of truncating each weighted term. (PX4-Autopilot#28516)
• The AlphaFilter library takes its sample interval and time constant in microseconds, and the float seconds overloads are removed, so a value in the wrong unit no longer compiles. Out-of-tree code that constructs the filter with seconds needs updating. (PX4-Autopilot#28421)

Control

• TBD

Safety

• Geofence Aware Return mode. (PX4-Autopilot#27145: feat(navigator): Geofence Aware RTL, PX4-Autopilot#28001: docs(navigator): [geofence] added some more warnings about limitations).
• Flight termination can now be used instead of a Descent mode as a fallback failsafe mode, allowing safer landing for unpiloted vehicles that carry a parachute. See Battery level failsafe (COM_LOW_BAT_ACT) and Position Loss Failsafe Action (new COM_POS_FS_ACT). (PX4-Autopilot#28064: feat(commander): add terminate options for critical battery and lost position failsafes).
• Failure injection ( SYS_FAILURE_EN) has been significantly extended. (PX4-Autopilot#27572, PX4-Autopilot#27832, PX4-Autopilot#27950)
  • Now applied on real hardware, not just simulators (injection hooks live in the shared sensor drivers).
  • Command handling is centralized behind a dedicated failure-injection manager module.
  • Multiple sensor instances can be failed simultaneously via a bitmask, and failures can be triggered from an RC switch.
  • Changed default behaviour of injected WRONG failure for Batteries, to publish a wrong level, and not stop publishing
• Motor failure recovery for hexarotors: on a single motor failure the control allocator removes the failed motor and additionally stops (CA_FAILURE_MODE = 1) or reverses (2) the motor opposite it to recover the lost yaw authority. Mode 2 requires a reverse-capable ESC and models the reverse thrust of a forward propeller with the new CA_REV_THR_FRAC (default 0.4). Reversible motor outputs on DroneCAN are now sent as signed RawCommand values (negative is reverse). (PX4-Autopilot#28078)
• Added RTL_TYPE=6 for battery-aware home priority return (PX4-Autopilot#26968). Returns to home if the estimated flight time to home is within the remaining battery time; otherwise returns to the closest rally point. Falls back to the closest safe point (home or rally) if battery time remaining is unavailable.

Estimation

• TBD

Sensors

• Enable u-blox Diagnostics with u-center while the vehicle's GPS runs as usual. (PX4-Autopilot#28280).

Simulation

• Gazebo: the GNSS failure injection commands (failure gps off, stuck and wrong) now apply to the NavSat data published by the gz bridge, consistent with the other simulator paths. (PX4-Autopilot#28398)

Debug & Logging

• TBD

Ethernet

• TBD

uXRCE-DDS / Zenoh / ROS 2

• TBD

MAVLink

• TBD

RC

• TBD

Multi-Rotor

• TBD

VTOL

• TBD

Fixed-wing

• TBD

Rover

• TBD

ROS 2

• TBD