Switching from iNav to Ardupilot for Flight Controller
We had been using iNav software for the flight controller but have decided to switch to Ardupilot the following reasons:
1) Ardupilot can have a "companion processor" like the Jetson Nano that
does vision/AI and decides things like which way to go. We really want to explore what can be done with AI on a solar powered airplane. Like can it avoid clouds and stay in the sun more, can it scan the horizon with a telephoto camera looking for boats, can it head for a boat automatically, etc. This seems fun.
2) Ardupilot can use a companion processor to communicate over cell data network (4G) to a ground station. With this we could fly all around Anguilla and still have communication between the ground station and the airplane. So from the ground we can change the mission plan during the flight. We could decide to go to a particular boat, or decide to come home because the change of rain has gone up. Or if we don't have AI avoiding clouds we could do it manually. While iNav can have waypoint missions, you can not modify them while the plane is in the air.
3) Ardupilot handles VTOL
Tailsitters. With VTOL we can have the plane take off and land from our house and fly out over the ocean. This
makes testing much easier. Packing up an airplane, putting it in the car, going to the RC airport, unpacking, putting together, etc takes a lot of time and work. If we just have to take a plane off the wall and walk outside, there is much less overhead per flight experiment. So the development iterations should go much faster.
4) We want to be able to have a computer decide what throttle to use to keep the voltage on the solar panels optimal. This saves the weight of MPPT hardware. We could do a bit of this in iNav but with a companion processor running Python we can have a more general and powerful algorithm for this.
5) We think a solar airplane can be a great fit for mapping missions. It can go back and forth taking pictures as long as the sun is enough and with a small battery always have enough to get to a landing point. Ardupilot Mission Planner supports mapping missions.
It seems iNav is great for FPV but for a ground station controlled smart airplane, we really need to use Ardupilot. So going forward we expect to use Ardupilot.
Ardupilot useful links
Difficult instructions for getting the F-35 in DFU mode so we can load Ardupilot onto it. That picture is just not clear enough. There are two square pads on the lower circuit board under the upper one. It is hard to reach, but you have to make a contact across those and then plug in the USB cord so it boots into DFU mode. For our second F-35 we found a much easier way. In CLI in iNav type DFU and FC goes to DFU Mode - and you can then load Ardupilot firmware.
First, be sure to get arduplane_with_bl.hex file. The "with_bl" means "with boot loader", which you want.
Overview of Ardupilot Quadplane - how Ardupilot categorizes things
The QRTH mode - Quadplane Return To Home - hover to land
New QuadPlane Features for ArduPilot Plane 4.1 - make nice landings
Video showing how to use joystick to control gimbaled camera in Ardupilot.
We have not found Ardupilot/F-35/DJI instructions. It seems we don't have the right serial port setup yet as moving remote sticks does not show up in Mission Planner yet.
We got F-35 DJI OSD to work with:
Serial0 = USB
Serial1 = speed 115 and protocol 23 = RCIN
Serial2 = speed 115 and protocol 33 = DJI OSD
Q_ENABLE=1 (have to refresh after this to see other Q settings)
We used full parameter tree to set:
SERVO1_FUNCTION 73 Throttle Left
SERVO2_FUNCTION 74 Throttle Right
SERVO3_FUNCTION 77 Left Elevons
SERVO4_FUNCTION 78 Right Elevons
There is an easier way. Go to "Setup", then "Mandatory Hardware", then "Servo Output".
Can use friendly menus to map servos to functions.
Our switch on RC8 has 3 positions so we can set 3 flight modes. Maiden flight will
QRTL - would love to see computer fly back to home
If a pure VTOL QRTL is desired, then you must disable the fixed wing RTL
and approach feature by setting Q_OPTIONS bit 16.
QHover Mode - autopilot helping with hover - middle area of throttle stays same altitude
Probably stay in this the whole first flight.
FBWA - Fly by wire A - wing mode or pre-flight checking
If we could have more than 3 flight modes it would be nice to also have:
We have two DJI air units (at home/work) so how to bind DJI is useful.