Set up the GPS sensor first (not covered here)
Phases
- Ascend (climb to specified altitude)
- Rotate (turn towards home)
- Fly home (fly towards takeoff point)
- Descend (hover within 5x5 m area of the launch point and slowly descend)
- Land (motors disarm upon ground impact)
Activate/Deactivate
- Activated using specified switch; deactivate by disengaging the same switch
- Set up in the “Modes” tab, for example like this:
- Set up in the “Modes” tab, for example like this:
- Can be activated by failsafe; sticks need to be moved more than 30% after regaining radio link to deactivate
- A specified number of satellites are required for GPS Rescue to work
- Display the number of GPS satellites on the OSD
Setting up (Betaflight Configurator)
Most of the GPS Rescue set up is done in the “Failsafe” tab (only visible after enabling “Expert Mode” in the header)
- Specify how the drone should behave immediately after failsafe (”Stage 1” lasts for a specified “guard time” to allow control link recovery)
Guard time for stage 2 activation after signal lost (seconds)set to 1.5- Center the roll, pitch and yaw sticks
- Set throttle to hover throttle
- Activate angle mode
- Activate GPS Rescue under “Stage 2 - Settings”
This will active GPS Rescue upon failsafe i.e. loss of control (radio) link. For certain environments e.g. freestyle flying in a forest, this is not recommended (as GPS Rescue can do more damage than just disarming and dropping to the ground). Also, failsafe only applies to radio control loss and not video loss. In the event of video loss, you can manually activate GPS Rescue if a switch was set up.
| Setting | Value | Description | Notes |
|---|---|---|---|
Angle | 40 | Maximum tilt angle allowed during GPS Rescue | Smaller drones may need a higher angle in strong winds to achieve the desired return speed |
Initial altitude (meters) | 50 | Minimum altitude above the takeoff point at which the drone returns | |
Descent distance (meters) | 30 | At what distance from home the drone starts to descend | |
Minimum distance to home (meters) | Below this distance GPS Rescue can’t be activated | ||
Ground speed (meters/second) | 10 | Note: in the CLI this value is in centimeters/second. Heading is more accurate at higher values | |
Throttle minimum | 1100 | Minimum throttle value used during GPS Rescue | |
Throttle maximum | 1600 | Maximum throttle value used during GPS Rescue | |
Throttle hover | 1280 (?) | Hover throttle value used during GPS Rescue | Accurate value needed. Use “Throttle %” OSD element. Correct value should cause the quad to climb slightly |
Ascend rate (meters/second) | 4 | Use a lower rate if using Li-ion or low C-rating pack | |
Descend rate (meters/second) | 1 | ||
Minimum satellites | 8 | GPS Rescue will not activate if fewer satellites are available |
- “Allow arming without fix” (enabled)
- Note that GPS Rescue will not work if the drone is armed before a GPS fix (satellite lock)
- Set “Altitude mode” to “Maximum altitude” (safest, but may be overly cautious)
- Set “Sanity checks” to “Failsafe only”
- Sanity checks (GPS connection, number of satellites, decreasing distance to home, etc.) are only performed when GPS Rescue is triggered by a failsafe, and not a switch
- If any of the sanity checks (conditions) are not fulfilled, the drone will disarm
- In Betaflight 4.4, there is now a limit of 20s of sanity failure even if all sanity checks are turned off
- Sanity checks (GPS connection, number of satellites, decreasing distance to home, etc.) are only performed when GPS Rescue is triggered by a failsafe, and not a switch
OSD
Useful information provided by GPS to display in the OSD: Gps sats, Altitude, Gps Lon, Gps Lat, Home Direction, Home Distance
Testing
Set up a failsafe mode in the “Modes” tab (fake control loss is safer than e.g. turning off radio)