Ian Hua / Quadcopter-mbedRTOS

Important changes to repositories hosted on mbed.com

Mbed hosted mercurial repositories are deprecated and are due to be permanently deleted in July 2026.

To keep a copy of this software download the repository Zip archive or clone locally using Mercurial.

It is also possible to export all your personal repositories from the account settings page.

You are viewing an older revision! See the latest version

Homepage

Table of Contents

  1. Introduction
  2. Partslist
  3. Sensors
  4. Frame
  5. Propulsion
  6. Electrical
  7. Radio
  8. Implementation
  9. RTOS
  10. MPU6050 Sampling
  11. Gyro Sampling & PID calculations
  12. RC & Bluetooth Command, and Telemetry
  13. Update ESC
  14. Results/Demonstrations
  15. To do/discussions (respective order of priority)

Feel free to look at code and implement your own. This article will be updated slowly, whenever I get a break from rock climbing, university and work commitments. Feel free to comment or ask me questions as need be.

Trung Tin Ian HUA - pHysiX Coding May 2014

Introduction

Quadcopter (X-Mode) using RTOS.

Insert picture of build

Partslist

Sensors

  • TiltyQuad
    • InvenSense MPU6050
    • HMC5883L
    • MPL3115A2
    • Onboard voltage divider for voltage sensing

Frame

  • Hobbyking SK450
  • Custom 3D printed motor mounts
  • 5.5mm thickness vibration-absorbing foam

Propulsion

  • 4x Hobbyking Blue 30A ESC, flashed with SimonK firmware
  • 4x Turnigy D2826/950kV motors
  • 2x LH 10x4.5 props
  • 2x RH 10x4.5 props

Electrical

  • 1x Turnigy 1000mAh 20C Lipo (Entire control logic uses 300mA peak)
  • 1x Zippy 5000mAh 30C Lipo
  • 1x Turnigy 5A max Low RF Noise BEC

Radio

  • 1x HC-05 Bluetooth (TiltyQuad IMU)
  • 1x Turnigy 9x v2 9 channel receiver
  • 1x Turnigy 9x v2 9 channel transmitter, flash with OpenTX and running lipo pack

Implementation

RTOS

4 main threads:

  • Thread1: Sample MPU6050 and calculate Yaw Pitch Roll angles from DMP quaternion
    • Settings: 100Hz sampling rate, 100Hz output FIFO buffer
    • Thread frequency: 100Hz
  • Thread 2: Gyro sample, and PID control loop. Currently only has Secondary/Inner loop (Rate control).
    • Settings: Input limits: -500.0, 500.0; Output limits: -200.0, 200.0; Output bias: 0.0, Automatic mode
    • Settings: Proportional gain: 8.0, No Integral or Derivative gain
    • Thread frequency: 200Hz (Primary/Outer loop will operate at 100Hz)
  • Thread 3: RC & Bluetooth Command, and Telemetry control
    • Settings: Default quadcopter is unarmed, and no telemetry is outputted.
    • Thread frequency: 50Hz
  • Thread 4: Update ESC pulsewidth
    • Note: My ESCs can apparently handle refresh rates of up to 400Hz. This means that the ESC should handle a 400Hz PWM pulse. This is distinguished from how fast I update the actual pulsewidth/duty cycle of my pulse!!!
    • Settings: PWM frequency: 200Hz, can be increased to 400Hz if the processor/code is fast enough.
    • Thread frequency: 200Hz. Thread should be increased to 400Hz since Secondary PID loop is running at 200Hz.

MPU6050 Sampling

To be completed

Gyro Sampling & PID calculations

To be completed

RC & Bluetooth Command, and Telemetry

To be completed

Update ESC

To be completed

Results/Demonstrations

Link to youtube video

To do/discussions (respective order of priority)

  1. Implement Integral control (P-PI or PI-P);
  2. Improve Control loop (remove slight oscillations, investigate D gain)
  3. Add support for EEPROM to store tuned gains outside of default
  4. Remove Bluetooth arming dependency
  5. Remap keyboard input for intuitive Telemetry/control
  6. Add in LCD output for offline setting/debugging
  7. Add in voltage sensing alarm
  8. Build GUI using Processing for Multiwii-like control
  9. Finish this article!
All wikipages