The ardupilot development team is proud to announce the release of version 3.1.1 of APM:Plane. This is primarily a bugfix release with a small number of new features.
The main bug fixed in this release is a bug that could affect saving parameters and mission items in the FRAM/eeprom storage of PX4v1/Pixhawk/VRBrain. The bug has been in the code since January 2013
and did not cause problems very often (which is why it hasn’t been noticed till now), but when it does happen it causes changes to parameters or mission items not to be saved on a reboot.
[color=#000080]Other changes in this release:[/color]
[ul][li]support for using a Lidar for landing for terrain altitude (see the RNGFND_LANDING parameter)[/li]
[li]improvements in the landing approach code, especially the glide slope calculation[/li]
[li]added LAND_FLAP_PERCENT and TKOFF_FLAP_PCNT parameters, to control the amount of flaps to use on takeoff and landing[/li]
[li]the default WP_RADIUS has been raised from 30 to 90. Note that the L1 controller may choose to turn after the WP_RADIUS is reached. The WP_RADIUS only controls the earliest point at which the turn can happen, so a larger WP_RADIUS usually leads to better flight paths, especially for faster aircraft.[/li]
[li]send gyro and accel status separately to the GCS (thanks to Randy)[/li]
[li]support setting the acceptance radius in mission waypoints (in parameter 2), which allows for better control of waypoints where actions such as servo release will happen[/li]
[li]fixed GPS time offset in HIL[/li]
[li]added RELAY_DEFAULT parameter, allowing control of relay state on boot[/li]
[li]fixed sdcard logging on PX4v1[/li]
[li]added GPS_SBAS_MODE and GPS_MIN_ELEV parameters for better control of the use of SBAS and the GPS elevation mask for advanced users[/li][/ul]