MultiCopter - Details of our Quadcopter Build

MultiCopter

The Multicopter Flight Controller board is a general purpose flight controller designed around the schematics for the MultiWii flight software which is written for Arduino based boards.

MultiCopter Project Menu
Introduction
Building the Board
Connecting the Board
Programming and Testing
Details of our Quadcopter Build
Schematic

Project Components
Links
MultiWii Website

Downloads
MultiWii Arduino Software V1.9 modified for IMU sensor board

Here is a picture of our quadcopter in all its prototype glory.

MultiCopter

The board is sitting in some foam to help dampen vibrations from the motors.

The frame is made from 1/4 inch aluminium tubing riveted to 2 peices of aluminium plate. There are two 11.1V Li-Po batteries wired in parallel underneath which together provide 4.4Ah.

The frame span is 21 inches

Other components are

Motors HiModel Brushless motor with propeller adapter
Propellors EPP1045 Contra-Rotating propellers (10 1/4 inch)
Speed controllers HiModel Fly-20A
RC System Hobbyking 6 channel digital HK6DF

 

Multicopter board wired up

Here is the board wired up to the RC Receiver on the left, and the speed controllers on the right. That's all you need for a basic setup. This is our original prototype version of the board and differs slightly from the current version.

Hobbyking RCHobbyking Radio Control

Speed Controller Mods

The HiModel FLY-20A are a great (and cheap) speed controller. They are happy at handling the 490Hz update frequency from the Multicopter Flight Controller board.

There is one downside to these that also effects many other speed controllers. They have a low voltage cutoff that is set too high and cant be disabled. This can lead to one motor having its power reduced before the others with the likelyhood of an expensive crash.

One greatl thing about these speed controllers though, is that its fairly easy to locate the ADC input that detects the battery voltage and solder a wire onto it to pull this input up to +5V. This little mod effectively disables the low voltage cutoff completely. Great news.

Here are some pictures of the HiModel Speed controller and the mod we have done

HiModel Speed Controller

HiModel Speed Controller mod

HiModel Speed Controller mod

Configuration for our Quadcopter

Using the MultiWii Configuration Software it is easy to adjust the settings for your particular quadcopter. All quadcopters are different, with different speed controllers, motors, wingspan (if that's what it's called), weight etc, so no one setting fits all.

The default settings are

  P I D
ROLL 4.0 0.030 23
PITCH 4.0 0.030 23
YAW 8.5 0.000 0
ALT 4.7 0.000 0
VEL 0.0 0.000 0
LEVEL 9.0 0.045  
MAG 4.0    

Using these settings there were two main problems

  • Oscillations
  • A tendency to roll right and pitch forward especially at takeoff

The oscillations were corrected by reducing the P in roll and pitch from 4.0 down to 3.0

The roll and pitch problem was corrected by setting the I in the LEVEL to zero.

  P I D
ROLL 3.0 0.030 23
PITCH 3.0 0.030 23
YAW 8.5 0.000 0
ALT 4.7 0.000 0
VEL 0.0 0.000 0
LEVEL 9.0 0.000  
MAG 4.0    


 

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