Pathfinder Edge: Mavlink
Pathfinder Edge: Mavlink
The pathfinder edge box listens to and publishes various Mavlink messages to and from the flight controller to faclitate various functions
Messages we listen to
The pathfinder edge box is listening to messages for drone status, Where the drone thinks it is, and RC channels. it requests all data streams like a ground control station but this is what it is looking for specifically
HEARTBEAT
RC_CHANNELS
GLOBAL_POSITION_INT
COMMAND_ACK
STATUSTEXT
Heartbeat
We listen to heartbeat to figure out what mode the drone is in. This is so we can determine if we are in guided mode and can send the drone motion commands.
RC Channels
We listen to rc channels to determine when to do specific actions and control specific actions in the system for debugging
chan 7
values above 1900 enable our targeting and waypoint navigation system
chan 8
values above 1900 enable our VPS engine to output location info to the drone instead of outputting location data from our reference GPS unit. upon a transition from below to above 1900 the VPS engine snaps it's location to the gps location. this functionality can be useful for getting a drone to a certain position with GPS
Global Position int
We listen to this information to determine which way the drone is pointing, how high the drone is off the ground, AGL, and where the drone thinks it is.
With respect to drone location, Most drones don't trust there gps sensors entirely on where they are. Because of this GPS location and drone location are almost never the same. For our more targeting and swarming functions we occasional send the drone locations that are offsets from its current position.
Messages we publish
The Pathfinder Edge box publishes messages for navigation and targeting tasks
MAV_CMD_DO_SET_MODE
MAV_CMD_CONDITION_YAW
MAV_CMD_DO_SET_SERVO
MAV_FRAME_GLOBAL_RELATIVE_ALT_INT
GPS_INPUT
MAV_CMD_DO_SET_SERVO
For targeting systems the box can tell servos to actuate at values of 988 or 2011. The specific channel it actuates is platform dependant.
GPS_INPUT
this is the message we use to tell the drone where it is at 5hz. it is important to note that a large portion of this message should be disregared as their values are not accurate to spec. See flight controller configuration for how to compensate for this
Time of week (still counts up but is not in reference to the week)
week of the year
Fix type (is always 3 even though practically we only have a 2D fix)
altitude
HDOP
VDOP
velocity
accuracy
satellites
course over ground