This repo contains a noobie quadcopter-build and implementation based on:

• Arduino Uno
• MPU6050 Gyroscope/Accelerometer module
• nRF24L01 Wireless communication module
• Power distribution board (XT60 male)
• Electronic speed controllers : Turnigy MultiStar 30A BLHeli-S Rev16 V3 ESC 2~4S, Racerstar
• Motors : 2205 2300kV (brushless) 2xCW/2xCCW Turnigy; [RaceStar]
• Props 5045
• 3S Lipo Battery (XT60 female)

• Maybe just get a decent flight controller and start flying and collecting data.
• PID only angles/ angles and angular velocities(might be easier for tuning). source
• Check refresh rate of of sensor.
• Checkout another interseting similar project.
• Tune PID parameters.LINK
• Refactor code in setup() function of flight controller: Rewrite mpu_setup
• Understand Transmitter AutoAcknoledge, DataRate... other settings
• Make prototypeboard to place gyro in the center of geometry/mass.
• Make condition to start mount motors dependent on two signals(joysticks) to reduce the probability of an error.
• Servo.h only works with 50Hz, Need higher refresh rate for a stable drone: https://forum.arduino.cc/t/adjusting-pwm-frequency/45204
  • Checkout:https://forum.arduino.cc/t/how-can-i-change-the-frequency-of-servo-library/148099/3,\
  • But writing directly to the outputpins and simulating the pwm pulse doesnt work yet (applaySpeed())
• Copyright-rules for code from other repositories?!
• Joystick dead-zone might be a problem.
• Install battery mount.
• Measure batteries voltage drop.

To have properly working ESC's/motors the ESC's have to be calibrated. This is done by applying the minimum(1000us) and maximum(2000us) PWM-signal(pulse-width-modulation) to the ESC's while they are connected to a battery.
ESC_calibration file can be used for that.
more about pulse-width-modulation: https://www.allaboutcircuits.com/textbook/semiconductors/chpt-11/pulse-width-modulation/ more about electronic speed controller calibration: https://ardupilot.org/copter/docs/esc-calibration.html\

To arm the ESC's, connect the battery with minimal throttle speed (1000us).

• PWM frequency for ESC's via analogWrite() rather than Servo.h 490Hz/50Hz -> might not be responsive enough

Usefull websites:

• https://www.teachmemicro.com/orientation-arduino-mpu6050/ <- explanation.

• https://lastminuteengineers.com/mpu6050-accel-gyro-arduino-tutorial/ <- basic accel./gyro readings (angles still need to be calculated)

• https://github.com/jrowberg/i2cdevlib/tree/master/Arduino/MPU6050 <- Complete library for MPU readings! (but how to include magnetometer?)

• digital low pass filter for MPU6050 20Hz?

• I2C - Communication

• DMP (digital motion processor) - programming to include magnetometer (future work)

• Interrupt Pin signals board when new data is available.

Similar projects: https://github.com/rohanverma94/The-Open-Copter/blob/master/quadcopter-documentation/quadcopter-arduino.pdf
https://github.com/lobodol/drone-flight-controller

Features that effect minimal loop time/refresh rate of flight controller: more info

• ESC's refresh rate. When max pulse is 2ms loop cant refresh motor speed faster.
• Gyro refresh rate & low pass filter(introduces delay)

• SETUP
  • Configure DMP(Digital Motion Processor) of MPU6050
  • Calibrate Gyro (on drone startup, else wrong offsets)
• LOOP(AIR-Routine)
  • Arm(AUX1) & Disarm(AUX2) drone.
  • read reviever data [throttle, yaw, pitch, roll] from nRF24L01-module
  • calc current angles [pitch, roll, yaw] from MPU6050
  • calc PID-Terms for each angle
  • Adjust ESC pulse (currently via Servo.h) based in PID-terms
  • (integrate battery voltage) TODO

https://github.com/akarsh98/DIY-Radio-Controller-for-Drone-Arduino-Based-Quadcopter

Lipo Guide: https://rogershobbycenter.com/lipoguide\ Why storage voltage is only important for long lasting (years) batteries.

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