BradWii

Introduction:

BradWii is open source multi-copter software.  The name BradWii comes from the fact that many concepts and some code were borrowed from Multi-Wii.  It's also a play on the original developer's name, Bradley (Call me Brad).  Though based on Multi-Wii, BradWii is pretty much a complete re-write.  BradWii is intended to be a platform on which other projects can be built.

Download:

The Arduino version can be downloaded here:

https://github.com/bradquick/bradwii_arduino/archive/master.zip

Features:

- Currently works with the following Hobby King boards:

	- Multi-Wii Pro 2.0
	- Multi-Wii 328p
	- Multi-Wii NanoWii

- Other boards should be easy to add for anyone with programming abilities. I tried to include only things that I have tested.

- Extensive use of fixed point math means the code is faster and more accurate.  Each value has 32 bit precision and the loop times are frequently under 2 milliseconds. All integration and filtering is time based, which means that constant loop times aren't critical.  The result is stable flight.

- Level, Acro, and Semi-Acro flight modes.

- Multi-Wii Config compatible (including bluetooth apps, etc).  Works on any (and multiple) serial ports.

- Simplified settings means there are fewer things (especially PID) that need to be adjusted.

- Auto PID tuning!

- Position Hold

- Mag Hold

- Altitude Hold

- Return to Home

- Standard or DSM2 Satellite receivers

- Throttle Helper - Automatically applies extra throttle when tilted in attempt to maintain attitude.

- Uncrashability Mode - Takes over when you get below critical attitude or get too far away.  Practice those Acro maneuvers without being able to dumb-thumb it!

- The project doesn't rely on any Arduino libraries which means that it can be easily developed on other development systems.  BradWii was originally developed on a Mac using Xcode.  The Xcode project can be cloned from the links below. You will also need to clone the libraries.  My avr tools are in a unique location, so some tweaking will be involved in getting the xcode version working (experienced programmers only). 

https://github.com/bradquick/bradwii
https://github.com/bradquick/avrlibraries

- Well commented, logically laid out code.  It is designed to be easy to add additional sensors and control boards.  Developers should find this code a good starting point for various projects.  The curious will find it easier to understand what makes their multi-rotors tick.

Quick Setup Guide:

- Download the Arduino Software.
- Download the BradWii Arduino project.
- Download a Multi-Wii config program for your comptuer.
- Edit the config.h file to match your particular setup.
- Upload the software to your control board.
- Connect to the board with the Multi-Wii config program.
- Calibrate the Accelerometer.
- Calibrate the Magnetometer (if your board has one)
- Set the checkboxes that select what the aux switches do.  Make sure one arms the board.  Set up another aux switch for autotune.
- Write the settings to the board.
- Before installing a battery, while still connected via Multi-Wii Config, use your transmitter to arm the board.  Apply throttle and other inputs and verify that the motor outputs react as expected.
-Calibrate your ESC's:
	- Remove the props
	- Edit config.h and remove the two slashes from in front of the ESC_CALIB_CANNOT_FLY
	- Re-upload the software into the control board.
	- Unplug the board from the computer.  Plug in the battery.  Wait for the ESC's to stop making their noises.
	- Unplug the battery.
	- Put the two slashes back in front of ESC_CALIB_CANNOT_FLY
	- Re-upload the software into the control board.	
- Remove the props, install the battery and test the operation.
- Fly it.
- While hovering, switch the autotune aux switch.  Let it oscillate for about 30 secconds (more is better).  Switch autotune off and back on again and let it oscillate again for 30 seconds.  Land, disarm, switch autotune back on and off again.
- Use Multi-Wii Config to set your aux switches to do other cool stuff.
- Fly


More Detailed Operating Instructions:

Config:

Brad-Wii is compatible with Multi-Wii config programs.  Use any of these programs to configure the software once it is installed.  Note that writes to eeprom won't take place if the aircraft is armed.  When you hit the "Write" button, confirm that the updating of the config program pauses for a second or so.  This indicates that the eeprom write is being performed.

Calibrating:

Set the aircraft on a level surface. Use the config program to calibrate the accelerometer.  This will also calibrate the gyro.  Calibration will only work when disarmed.

If you are using a compass (magnetometer), also calibrate the compass.  Click the calibrate mag button on the config program and then rotate the aircraft in all directions for 30 seconds. For best calibration, first figure out which direction the magnetic field points (highest mag values in the config program).  In most places, it points down into the earth at a steep angle.  While calibrating, make sure both ends of each axis get pointed in this direction during the 30 second period.  When the config program starts updating again, the calibration is done.  Yaw the aircraft 360 degrees and verify the compass feedback on the config program.  If it doesn't look right, repeat the calibration.

The LED:

The LED stays lit when the signals from the gyros and accelerometers indicate that the aircraft is stable.  If you move the aircraft around by hand, you should notice the led going off when it's accelerating. When hovering, the LED should be lit most of the time.  If it's off more than it's on during hover, then you probably have too much vibration from the motors feeding back into the control board.

When using a GPS, the LED won't light until 5 satellites have been acquired.

Arming:

Arming currently needs to be done using Aux switches.  By default it arms when Aux1 goes high.  It will only arm and disarm when the throttle is low.  When armed, the props should all spin at a low rate.

Flight Modes:

The software defaults to Level mode, where the angle of the transmitter stick corresponds directly to the angle of the aircraft.

Acro mode can be turned on via Aux switches when setup in the config program. In acro mode, the angle of the transmitter stick corresponds with the aircraft's rate of rotation.

Semi Acro mode can also be set via Aux switches.  Semi Acro mode is a mix between acro mode and Level mode.  This the easiest mode to do flips without crashing.

Acro rotation rates can be set using Multi-Wii Config.

Maximum tilt angles (when in level mode) and rotation rates (when in acro mode) have dual rates.  The high rates (or they could be lower rates if desired) can be activated by aux switches when setup using the Multi-Wii Config program.  One preferred setup is to have high angles active when aux2 is switched off, and to have low angles, high rates, and semi acro mode active when aux2 is switched on.

Autotuning:

To use autotuning, use the Multi-Wii Config program to assign autotuning to one of your Aux switches.

Hover your aircraft as still as possible and flip the the aux switch to turn on autotuning.  The aircraft should start to roll back and forth.  If you can, let it do so for 30 seconds or longer.  While it's doing this, try to use only pitch and yaw to bring keep the aircraft from flying away.

Flip the aux switch off, then back on again.  This time it should start rocking in the pitch direction.  Again, try not to use pitch control while it's doing this.  After 30 seconds or longer, turn the switch off and test it.  You can use the switch as many times as you want.  It will alternate between tuning roll and tuning pitch.

If you want the new settings to be saved to eeprom, land, then dis-arm, then switch the autotune aux switch on while dis-armed.  This will cause a write to eeprom.

Throttle Helper:

Throttle helper mode automatically applies extra throttle when the aircraft is banked.  Without throttle helper activated, when you bank, you lose vertical lift, so if you don't apply extra throttle, you lose altitude.  Throttle helper applies the extra throttle for you so that you don't lose altitude.

Altitude Hold:

If you have a barometer, altitude hold keeps the aircraft at a constant altitude by varying the throttle setting automatically.  Throttle helper is automatically activated when altitude hold is activated in order to minimize altitude fluctuation due to banking of the aircraft (flying it around).

Position Hold:

This holds the aircraft at the GPS location where position hold was activated. Note that altitude hold isn't automatically activated with position hold, so if you also want altitude hold, you need to set it also.

Return To Home:

When return to home is activated, the aircraft will return to the home position, which will be where it was armed.  Note that altitude hold isn't automatically activated with return to home, so if you also want altitude hold, you need to set it also.


Uncrashability Mode (somewhat expreimental):

Uncrashability attempts to make the aircraft uncrashable by taking over the controls when danger approaches.  It uses the barometer to determine altitude and optionally uses the gps to determine location.  The home location and altitude are set when uncrashability is activated, so it should be activated when the aircraft is at a safe altitude.  If the software anticipates that the altitude will go below the home altitude, it will automatically bring the aircraft to level, then apply throttle to get it back to the home level.  If it goes more than a pre-determined distance from the home location, it will take over the control of the aircraft until it gets back in bounds.