Quadcopter using a Multiwii – Multiwii

The final part of the assembly corresponds to the MultiWii configuration. This is the software that is on the flightboard and controls Quadcopter.

If you want to check part 3, where we started the assembly, you can do it on here.

To load the MultiWii for the flightboard, we need:

• computer
• FDTI cable
• flightboard
• Arduíno IDE installed on the computer (can be downloaded from here)

Download the MultiWii from the official website and decompress. Then open the MultiWii software in the Arduino IDE (we can open it through the file “MultiWii.ino”).

Inside the “config.h” the following setting must be changed:

Section 1

• In “The type of multicopter” we must choose the type of copter we are mounting. This copter is a Quadcopter in “X” (QUADX)
• In “boards and sensor definitions” we must choose which flightboard we are using. This flightboard is a “CRIUS_SE_v2_0”

Section 4

• In “Aux 2 Pin” we must activate the option “RCAUXPIN8”. Defines in which flightboard connector the “AUX2” channel will be connected.

Section 7

• In “motor, servo and other presets” the option “MOTOR_STOP” must be activated. This option will indicate the flightboard that, when the throttle is at a minimum, the engines must be stopped. If this option is disabled, with the throttle at minimum, the motors maintain a minimum rotation.

To activate each one of the options the comment indicator from the beginning of the line ( // ) must be deleted.

Next load the MultiWii onto the flightboard. To do this, connect the FDTI connection from the flightboard to the computer via the FDTI cable. Next, prepare the Arduino IDE to identify the flightboard.

In the “tools” menu, in the “board” option choose “Arduino / Genuino Uno”. In the port option, choose the port where the flightboard is connected (in this case it is “/dev/cu.usbserial-A50285BI”).

Next, press the second Arduino IDE button to load the software to the flightboard.

Arduíno IDE will compile and check for errors on the configuration. If there are no errors, it will load the MultiWii to the flightboard.

MultiWii Configuration

For the second part of the configuration, we will use the MultiWii Conf software that is also in the MultiWii folder.

In Multiwii conf various options can be configure, including flight mode, and auxiliary channel functions. We can also calibrate the magnetometer and the accelerometer. The MultiWii, in addition to the four main flight channels, supports and allows you to configure four auxiliary channels.

First, it is necessary to calibrate the accelerometer and the magnetometer. To make these calibrations, use the two buttons “CALIB_MAG” and “CALIB_ACC”.

For the accelerometer calibration, place the Quadcopter on a flat surface and press the “CALIB_ACC” button.

To calibrate the Magnetometer, click on the “CALIB_MAG” button and then turn the Quadcopter on the three axes (X, Y, and Z).

Then we set the flight mode. The MultiWii supports three flight modes: Horizon, Acrobatic and Angle, and the most reliable is the Horizon mode. You can see a detailed description of these modes in the “Programação, parte 2” video of OOZ Labs at minute 2:19.

Other options that i have activated are the “Baro” and “Mag”. In my case, “Baro” is activated when “Aux2” is set to “High”, and tells MultiWii to maintain the altitude. We can release the sticks that the MultiWii will adjusts to maintain altitude.

The “Mag” mode is activated when the “Aux1” is set to “High” and tells the MultiWii to maintain the same direction during the flight until there is a “Yaw” command. If this mode is off, there is always a slight deviation of direction when the Quadcopter advances.

Then click the “Write” button and the settings are saved in MultiWii.

Flight Test

WARNING: propellers in motion may cut and injure.

To test the Quadcopter, it is convenient to be in an open area and free of obstacles (eg trees). Should create a flight checklist so nothing is forgetted. Below I leave mine to have a reference. The last thing to do, before flying, and the first thing to do, after flying, is to turn the Quadcopter’s battery on and off, so there are no accidents. Do not turn the Quadcopter on without turning the remote on, or turn off the remote before turning off the Quadcopter. If you turn on the Quadcopter with the remote off, when you turn on the remote this may have some option activated, which the Quadcopter will respond immediately and may cause accidents.

To start the flight, you must arm Quadcopter. To do this, with the throttle at minimum, push the “Yaw” to the right until the blue led comes on. It’s ready to fly. To disarm, the process is the reverse. With the throtlle at minimum, push the “Yaw” to the left until the led is off. As a safety measure, the MultiWii will only “arm” when it is horizontal. If the blue LED is blinking, before “arming” it means that it is not horizontal and, for safety reasons, it will not “arm”. If it blinks, even when it is horizontal, the calibration has not been performed correctly and must be repeated.

From here, is testing, practice and have some drops (guaranteed). Should always have lots of propellers, because it breaks a lot. All it takes is the propeller hits something when it takes off or lands, or crashes with something in flight to break it.

For a more detailed explanation of the construction i recommend that you see the OOZ Labs Series 1, where there is a video explaining the whole process.