Would be fun to have bicopter support (Avatar type).


Two rotors and two servos outputs.


Servos outputs would need diffential mixing.



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Hi, thanks, and really sorry for the late reply, ive been busy with college all week. I will start with the yaw and elevator connections. The individual servos work fine when directly connected to the gyros, but once the Vtail mix is introduced, theres just no response in the servos, they arent getting the signals from the Tx anymore, literally dead!...

Next, when i hook up the aile gyro direct to the ESC, they (esc) seem to go haywire, causing the motors to twitch round in steps .. at this point, i have no control from the Tx , the motors just keep twitching while ESCs keep beeping abnormally. 

When i connect the vtail mixer and gyro to the ESC according to the diagram, they just wont arm... like the servos, they're dead without any response whatsoever.

I figured the problem maybe power supply (Vtail mix may have disrupt power delivery from Esc where battery connects to) but the receiver didnt indicate any problems.

I must apologise in advance because my RC knowledge is rather shallow. Ive done some research & it seems these builds almost always require some sort of PID control which i dont have..might that be the issue?

I will try to upload some pictures next..




The mixers may not like the output coming from the gyros.  Try hooking up the servos, mixer and receiver - without the the gyros in the circuit.



Thanks for the tip, yeah the mixers didnt cope well with the gyro signals, ive since changed the gyros to proportional ones, now the system works..planning some test flights in the future..

I made some test with a modified code.

I need assistance from a developper because I am not a SD.

In AP_MotorsMatrix.cpp I changed this:

 // mix roll, pitch, yaw, throttle into output for each motor

for( i=0; i<AP_MOTORS_MAX_NUM_MOTORS; i++ ) {

if( motor_enabled[i] ) {

motor_out[i] = _rc_throttle->radio_out +

_rc_roll->pwm_out * _roll_factor[i] +

_rc_pitch->pwm_out * _pitch_factor[i] +




with this:

// Motors

i = 0;

if( motor_enabled[i] ) {

motor_out[i] = _rc_throttle->radio_out +

_rc_roll->pwm_out * _roll_factor[i];


i = 1;

if( motor_enabled[i] ) {

motor_out[i] = _rc_throttle->radio_out +

_rc_roll->pwm_out * _roll_factor[i];


// Servos; Change signs + to - for servo revers

i = 2;

motor_out[i] = 1500 + _rc_pitch->pwm_out * _pitch_factor[i] +

_rc_yaw->pwm_out * _yaw_factor[i];

i = 3;

motor_out[i] = 1500 + _rc_pitch->pwm_out * _pitch_factor[i] +

_rc_yaw->pwm_out * _yaw_factor[i];


It works but there are some problems.

1. The value 1500 must be replaced with a more appropriate expression.

2. The term _rc_pitch->pwm_out * _pitch_factor[i]  produces to small servo movement. I need +/- 45 degrees similar to camera tilt. The idea is to preserve the desired position of the propellers when the frame is balancing.

3. The stability patch that follows in the code must be adapted.

4. Are the terms _roll_factor[i]  _pitch_factor[i] and _yaw_factor[i] redundant in this case?  

Can somebody help me out?



Why not just use an FCU that will auto stabilize it , the FCU doesa all the mixing for you.

What do you mean by FCU?

Flight control Unit , pre-programmed and pre-made board , they are cheap , and plug and play.  http://www.hobbyking.com/hobbyking/store/uh_viewItem.asp?idProduct=...
I say this because no matter how long I search i cant find a mode for the Ardupilot bicopter.
This is of course entirely up to you. 

I use the KK2.1 with Steveis 1.17 pro firmware and it works pretty good with out the use of a WSM. Check it out in my video.


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