dRehmFlight VTOL Is a Barebones Flight Controller for All VTOL Vehicles
Nick Rehm's powerful hobbyist flight controller costs under $30 and weighs less than 15 grams.
From simple multirotor to more complex transitioning vehicles, Nick Rehm's dRehmFlight VTOL is intended to control all types of vertical takeoff and landing (VTOL) vehicles. This controller and stabilization project was specially designed for users not versed in coding who still want to make use of an advanced VTOL platform that requires relatively quick custom mixing while the vehicle is in the air. Intended as a relatively powerful hobby-level flight controller, the dRehmFlight uses the Teensy 4.0 board. This microcontroller enables the code, an easily-understandable flow of discrete operations, to run at incredibly high speeds. The code is written to allow anyone with a basic knowledge of coding in C/Arduino to make the changes needed for their application and get their vehicle up in the air.
dRehmFlight is the code, and the default hardware necessary to get started — the Teensy 4.0 and MPU-6050 IMU — cost under $30 and weigh less than 15 grams. The use of the Teensy 4.0 is driven by the need for something fast enough to run flight control code without the need for advanced optimization techniques required when using just an Arduino. With the add-on, the Teensy functions identically to an Arduino but run at 600 MHz. The Arduino Nano, which is of a similar size, runs at only 16 MHz.
Code modifications and compiling are done via the Arduino IDE with Teensyduino add-on. The default code, available with comprehensive documentation on GitHub, supports outputs using OneShot125 Protocol and seven conventional PWM outputs for ESCS and servos. It also provides the ability to modify the code for custom setups with extra outputs. Support is available for conventional PWM, PPM, or SBUS receivers and for MPU-6050 and MPY9250 IMUs. The mixer is easy to control, with stabilized axis variables and the ability to pass commands directly from the transmitter to the motors or servos. There are three PID controller types, including rate and angle-based setpoint, as well as simple variable fading.
A video with a more in-depth explanation of the project and some demo flights can be seen below, while more details are available in Rehm's project page.