Hi I am developing a very large 200 lb unmanned drone and I want to get a good enough tune on the pids in the flight controller. Adjusting the pids by flying it.can be very dangerous both to the vehicle and to people, if they are really off. The vehicle I am building is basically a tricopter with two 10 kW motors in front and a 18kW cont/40kW peak in back. The vehicle is very similar in function to the Convergence tilt rotor RC model. Please refer to the following link for more details about the vehicle:
The idea I have is to place a small piece of wood at the base of the vehicle, at its CG, so that the ehicle will pivot at this point. Then I plan on turning on the motors and bringing up the throttle a little below the point where it wants to take off. At this point the vehicle will be level and flight controller will try to stabilize the vehicle horizontally. At this point I can pulse the pitch control on the transmitter, causing the vehicle to lift up on one end. With this setup I can now safely tune the Pitch pids so that the vehicle stabalizes quickly after it is pulsed. I will then copy the PID values for Roll,which will give me good values to start with when I try to tune the pids while flying.
I would like to know if this method would be accurate enough to get a good enough PID tune so that it will stabalizes good enough when flying in the air, so that I can continue refining the tune in flight?
If you can create a model of the aircraft in a sim, you can get close enough to the correct PIDs that maiden flight is safer. It is very dependent on the efficacy of the model though.
Hi Charlie,
I have made a Realflight 7.5 sim model of the full scale unmanned drone. But the sim does not use a flight controller. I am not sure it is available on ver 7.5. But it is available in the newer versions, because the Convergence RC model is one of the models you can test, and this model is very similar in functionality to my vehicle. The main problem is the motors for something this size are not typically available. I found on the internet a motor, but it weighs 50 lbs min and this is a lot more than any of my motors. My front motors weigh 5 lbs ea and my back motor weighs 13 lbs. So to make the vehicle fly in the sim I had to make the motors more powerful in order to lift the weight. Here is a link to see the CAD model flying in VTOL mode in Real flight 7.5:
I don’t know if ArduPilot SITL works with Realflight versions less than 9. That would be the key to getting a better guess at the tune. I know it is possible to put a quadplane in Realflight, but the version might be an issue. There is a lot of information about SITL in the wiki. Simulation — Dev documentation
Modifying or creating models in Realfight is possible. There are several examples available in this repo. SITL_Models/RealFlight at master · ArduPilot/SITL_Models · GitHub If you already have the cad, it should be in your reach to get it into a sim. Especially Realflight.