Nature is class. Birds are also class. If you have ever seen a bird gliding in the wind, that is exactly what this project is trying to emulate. The world record flight time for a two-seat glider is over 70 hours set in 1961 in Hawaii. This record has not been between because it is seen as being a pointless and dangerous challenge. Alpine swifts can fly for 6 months at a time without landing in fact.
So it is not too crazy to imagine building an autonomous glider that can remain airborne for large periods of time. To do this, a stable control system and suite of algorithms is required.
I bought a hand thrown glider for €5 in Lidl. The first thing to do was to put a motor and servos on it. Initially it would be controlled using my stock RC controller and receiver.
There are two roll servos, one pitch servo, one yaw servo and a propeller BLDC. There will also be a 9DOF IMU, altitude barometer, windspeed sensor, GPS, and RC receiver.
The final board for testing will place an ESP32 inbetween the RC receiver and the motors so that PID control and more complex controllers can be implemented.
PID controllers will be implemented for each of the axes for simpler intial controls and some level of automation.
One of the goals of this project is to create a robust control system that can withstand imbalance in the plane, gusts of wind, stalling and the ability to take tight turns. PID controllers are the first initial starting point, but many changes will be necessary.
Waypoints can be added to form a path which the plane will follow. GPS, altitude and a good control system are all necessary for this part of the project.
Much like how birds glide in the wind, this stage will do the same. Wind direction needs to be determined. Then an algorithm needs to be developed to maintain this direction and glide efficiently.
Thermals provide a good source of lift on a sunny day. Thermal identification and following could help increase flight time.
Once wind sailing has been mastered, solar panels can potentially increase flight time. Power/weight ratio is very important.
The goal is to maximise the flight time of the glider, using thermals, solar and wind.