Geofence configuration

Soft geofence is the standard geofence functionality of ArduCopter. The basic idea behind the geofence is that you have a well specified global flight area boundary and if any of your drones go out of this area (either outside of a global geofence polygon horizontally, or above a maximum flight altitude, or further than a given predefined maximum distance from home), then a user-configurable geofence action kicks in.

When using Skybrush Live for show execution, you do not have to manually touch the standard fence parameters, as they will be configured automatically upon show upload on each drone, assuming that you have setup your geofence properly in the Geofence dialog.

The main vulnerability of such a global soft geofence is that drones can potentially gain substantial speed away from their desired show trajectory by the time they reach the global geofence boundary and hence can follow their routes "like a stone that’s been thrown" even when disarmed at the edge (which is by the way not even a possible standard geofence action option). That is why in drone shows, where there is less human attention on individual drone paths, it is advisable (and with many flight authorities it is even required) to also have a hard or bubble geofence configured.

Hard geofence is a Skybrush-specific addition to the firmware that disarms drones that remain outside of the soft geofence for a given time period.

Hard geofence can be configured with our custom SHOW_HFENCE_* parameters.

If you enable the hard geofence with SHOW_HFENCE_EN, make sure you specify a proper SHOW_HFENCE_DIST distance and SHOW_HFENCE_TO timeout value. Setup these parameters carefully to avoid false positives that disarm your drones superfluously mid-air.

Bubble fence is yet another Skybrush-specific geofence type dedicated for drone shows, where trajectory following is performed in 4D, i.e., where drones have to be at a specific location at a specific timestamp. The bubble geofence is a small spherical relative geofence that moves with the desired position of the drone along the show trajectory in time. If the drone deviates from its desired position over a spatial threshold for a given amount of time, the configured bubble fence action kicks in immediately.

The bubble fence is the most rapid way to detect and react to deviations from expected behaviour, hence it is a very powerful safety tool in drone shows, where a skyrocketing or misbehaving drone can cause substantial damage in the environment or the audience.

Bubble geofence can be configured with our custom SHOW_BFENCE_* parameters.

If you enable the bubble geofence with SHOW_HFENCE_EN, make sure you specify a proper horizontal and vertical distance with SHOW_BFENCE_DXY and SHOW_BFENCE_DZ respectively, and a SHOW_HFENCE_TO timeout.

For the bubble geofence you can also configure the desired failsafe action to use with the SHOW_BFENCE_ACT parameter. Unlike with the soft geofence, here you can also specify "Disarm" as your failsafe action, but pay attention to use it with care.