VC-06 Intermeshing Tiltrotor Quadcopter Frame

Intermeshing Tiltrotor Quadcopter. Main rotors provide only lift, tail rotors vector to control attitude. It always crashes outdoors.
Not sharing the firmware because it's too messy. Good luck fitting any commercial flight controller in it.

Screws:

• M2 countersunk 5mm x6
• M2 countersunk 5mm machine screw x2
• M2 8mm x4
• Main motor nuts must be shortened to not get hit by propellers

Uses 1 2mm-thick 25mm-diameter O-ring as vibration damper

• Firmware: coded from scratch
• Flight controller: Arduino Nano 33 IoT, Cortex M0+ SAMD21, 48MHz
• IMU: built-in LSM6DS3
• PID Loop/ESC update rate: 500Hz
• IMU read frequency: 1000Hz
• Servo update rate: around 1000ms/4ms = 250Hz
  • pulses fire consecutively, rate depends on total servo pulse width
• AHRS:
  • tracking X axis unit vector (front) and Z axis unit vector (up) of the world coordinate, rotate by small angle sine approximation
  • complementary sensor fusion on world Z axis
  • correcting skew with Gram–Schmidt process
  • mostly fixed-point calculations (Interestingly on this chip using sqrt() function is faster than the fast inverse square root algorithm)
  • fixed-point table search interpolation trigonometry functions.
• Tuning Interface: web UI over Wi-Fi
• ESC protocol: DShot600 using bit-bang
• ESC: 4-in-1 ESC with 20x20 mounting hole
• Battery: 2S 860mAh Li-po
• Servo voltage regulator: LMS1117 5V
• Main motors: Brandless 1806 2280kv x2
  • body height (shaft starting point) 15.7mm
  • mounting hole (diagonal) distance 12mm and 16mm
• Main rotors: 2-blade 8045 F330 x2
  • mounting hole depth 7mm
• Tail motors: Tarot MT1104-4000KV x2
• Tail servos: Emax ES9250 x2
• Tail rotors: GEMFAN 2540 GR8202-11 x2
• Receiver: Flysky FS-RX2A
  • serial iBUS