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

-

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!

Comments

Post a Comment

Popular posts from this blog

V-22 Osprey Project - Design Changes for v3

-
Image
It's been a busy end of 2021, and as we start 2022 I'm getting closer to building version 3 of the Osprey wing.  The single biggest problem I've faced is the amount of backlash in the direct spur gear drive of the tilt mechanism.  It introduces some nasty instability that, left unchecked, would likely destroy the model in flight. I've investigated other tilt mechanisms, but the one I keep coming back to is the rack and pinion design that Tom Mast uses in his model at Rotormast.  His design uses a high-torque digital servo with a small pinion gear driving a rack attached to the rotor nacelle.  The servo has been modified with an external potentiometer that's driven by a gear on the translation tube to give positional feedback to the servo.  I like this design a lot because 1) It works, and his model is proof, and 2) it requires less torque from the servo and has less backlash. I ordered the pair of modified servos, potentiometer, and rack from Tom's site and star...
Read more

Whereabouts Clock Update

-
Image
After a few months, Life360 has gone the way of Apple and locked down the API I used to get location data from the phones.  This is disappointing, but inevitable. I found on a forum for Home Assistant that the app OwnTracks might be a suitable alternative. It's a neat little app that will trigger the phone to send its location data via MQTT to a server that you specify. I had to rework the code a bit, but the new operation is as follows: OwnTracks on the phone will push location data per its configuration to the MQTT server (Docker container) The Mosquitto (MQTT Broker) container will receive the data and forward the data to its subscribers The MQTTWarn container is a subscriber and translates the received data and adds it to the MariaDB database The Apache web server hosts a Python CGI script that is checked each minute by the Arduino microcontroller.  If the data has changed, the hands are moved to the new location. The only exposed port to the Internet is TCP 1883 for...
Read more

Whereabouts Clock: New Clock Mechanism

-
Image
 When I made the first mechanism of the Whereabouts Clock I utilized sail winch servos to get a motion that was at least 360 degrees.  Most RC servos are limited to about 180 degrees before they hit a physical limit.  I always wanted to create a clock with motors that weren't limited in the number of rotations, such as a stepper motor. However, stepper motors don't retain positional accuracy after a power loss.  The motor drivers only know "left" or "right" and a number of steps.  If the motor is moved, or power is lost, it has no idea where the motors are any longer.  In most control systems using stepper motors there are limit switches that are triggered to "home" the motors to a known position. Also, the Arduino Uno is limited in the number of IO pins.  Most stepper motor control requires at least 4 pins and additional lines for motor enable, micro switches for positioning, etc. A while back I purchased an Arduino Mega and a six-pack of 28BYJ48 ...
Read more