mavsdk_skywriting's Introduction

Offboard Skywriting Mode

MAVSDK Application

Gordon Keller

Rev. 1 1/3/20

A MAVSDK-based implementation of a multirotor skywriting mode that:

Establishes connection to PX4 system
Takes a string argument of the form 'WRITE THIS' and converts it to waypoints and trajectories
Executes mission with an optional trigger for light, laser, smoke element, etc.

Building

*MAVSDK libraries must be installed on the system, and you must have PX4 locally to run SITL simulation

cd /{PROJECT DIR}
mkdir build
cd build
cmake ..
make

Running (in simulation)

Run JMavSim

cd .../src/Firmware/ (wherever you have PX4 source installed)
make px4_sitl_default jmavsim

Run Offboard Program

./offboard_skywriting udp://:14540 'ABCDEFGHIJKLM
NOPQRSTUVWXYZ'

Output (retrieved from flight log):

This command will initialize vehicle takeoff sequence (if not already airborne) and will traverse the alphabet in two lines. *Program start quirk will reject first offboard call in simulation -- simply run the program again and the sequence will start.

Project To-Dos

Implement better PID for trajectory control
Add flags/modifiers for skywriting setting #defines in main
Add safety protocols
Create GTests for each library
Add external instrument (LED, smoke machine) controls (refer to https://ardupilot.org/copter/docs/common-external-leds.html -- even though this reference is for ardupilot, should be a programming option for PX4)
add manifold mapping to create a surface to write on in the sky
parameterize things like letter max speeds, intensity of letter (i.e., density of smoke plume, or the brightness of leds)
for smoke, incorporate logic to have outlet negate vehicle velocity (i.e., point in reverse direction of flight and match the traversal speed to have it stay stagnant in air)
add geofencing for safety

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