V-22 Osprey Project - Christmas Additions and New Flight Controller

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After the failure last summer I had to put the project down for a while.  After reviewing the footage and discussions online I decided that I needed new ESCs that had a governor mode and a new flight controller.

The ESCs I was using came with the KDS helicopter model and were not high-quality units.  Although similarly packaged, it was clear they were not 100% the same as the beep codes were a bit different and the throttle profiles were also a bit off.  I tried to compensate with measurements and split throttle curves, but there was no way I was going to be remotely certain that the rotors would turn at the same speed.  For Christmas, I got a pair of Castle Creations Talon 60 ESCs.  I have some Castle ESCs in other models and they are wonderful!  The price reflects their quality, though.  I programmed these in three RPM bands I thought appropriate to start with:

Normal: 2500
Idle Up1: 2750
Idle Up2: 2900

Based on the motor, gearing ratio, recommended headroom, and gut feel these seemed to be good to start with.

However, the ESCs wouldn't be enough to fix the control issues I was having.  Many people suggested that I get into ArduPilot and use its VTOL modes for the Osprey.  I thought it was a good start, so I purchased a kit from Amazon.

My first thoughts were that ArduPilot is complex!  I started diving into the wikis, forums, discord server, and other locations to learn as much as possible about this new world.  I'm not a programmer by profession, but I'd say I'm at least a good intermediate at it.  What I eventually found is there is currently no cyclic pitch controlled, tiltrotor bicopter model in the ArduPilot codebase.  I would have to write it myself.  As I continued to research how to start, I came across Nick Rehm's post on the FliteTest Forums discussing his dRehmFlight VTOL flight controller.  The simplicity of his controller based on the Teensy 4.0 board and GY-521 MPU6050 IMU really stood out.  I happened to already have the IMU on hand, so I picked up the Teensy board he recommended.

Within a couple of days, I understood how the code worked and began modifying it for the Osprey.  The results are pretty spectacular:


At this point, no transition mixes are implemented only hover mode.  The tilt servos do work but need some additional fine-tuning.  The flaperons and elevator are not connected yet and the elevator has taken some damage from being banged around the garage for the last six months.

Thanks to Nick and his dRehmFlight VTOL project for giving me hope that this project might yield something flyable!

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