Hi Pirates, based on Hein's comments, I'm going to try to explain how is the mixing of the motors done, depending on the layout/position of your ship's motors.
All mixing depends directly on the motor's positions and layout proportions. Depending on it's position each motor needs to apply different strength to pitch and roll axles. In other words, the farthest a motor is from a axle, the stronger it will have to pull.
This strength is set for each motor in the motor mixing (motors.pde) as meanings of a percentual value, that will multiply pitch and roll values used to calculate the final value for each motor.
When the percentage is 100%, it is not necessary to add any value, as we would be multiplying by 1.
Pitch and Roll Axles
Pitch and Roll axles will be used as reference to find the needed strength for each motor:
The axles layout will help to understand and locate what will the values for each motor be, and it's sign.
As for the Yaw, things are simpler, as it just depends on the rotation direction of the motor:
If Motor turns ClockWise (CW) Yaw is Negative.
If Motor turns CounterClockWise (CCW) Yaw is Positive.
I will try to explain it using exampes for the frames we commonly use:
Quad + mode
Ok, let's start with a simple Quad in + mode:
As all 4 motors are on the axles, they all will have 100% and 0% as strength values, in more detail:
Motor Pitch Roll Yaw
0 Right CCW -0% -100% +
1 Left CCW +0% +100% +
2 Front CW +100% 0% -
3 Back CW -100% 0% -
Thus the resulting pseudo-code would have these signs and values:
rightCCW = - (0 * Pitch) - (1 * Roll) + Yaw
leftCCW = + (0 * Pitch) + (1 * Roll) + Yaw
frontCW = + (1 * Pitch) + (0 * Roll) - Yaw
backCW = - (1 * Pitch) - (0 * Roll) - Yaw
and the final code in Motors.pde, adding throttle and controlling total motor value not to get out of bounds, would be:
BUT, as we would be lowering the overall power to 71%, and all values are the same we can simply uses 100% for all values, this way we're still keeping the same proportion of strength between motors, so there will be no difference in stability, but we will be getting all the available power.
and the final code in Motors.pde, adding throttle and controlling total motor value not to get out of bounds, would be:
So all 4 left and righ motors will have a pitch strength of 50% and roll of 87% while front and back will only have 100% on pitch and no effect on roll.
and the final code in Motors.pde, adding throttle and controlling total motor value not to get out of bounds, would be:
NOTE: The current NG code, is not using the 87% on roll, but 100%; in this case it is like the all four left and right motors were a bit farther away from center (13%).
Hexa H mode
Next, HEXA in H mode, with three motors on each side in a "H" shape, forming a perfect square:
More in detail:
Motor Pitch Roll Yaw
1 FrontLeft CW +100% +100% -
6 Left CCW +0% +100% +
5 BackLeft CW -100% +100% -
2 FrontRight CCW +100% -100% +
3 Right CW -0% -100% -
4 BackRight CCW -100% -100% +
Thus the resulting pseudo-code should have these signs and values:
FrontLeftCW = + (1 * Pitch) + (1 * Roll) - Yaw
LeftCCW = + (0 * Pitch) + (1 * Roll) + Yaw
BackLeftCW = - (1 * Pitch) + (1 * Roll) - Yaw
FrontRightCCW = + (1 * Pitch) - (1 * Roll) + Yaw
BackRightCW = - (0 * Pitch) - (1 * Roll) - Yaw
BackCCW = - (1 * Pitch) - (1 * Roll) + Yaw
So in this case as all values are 100%, no value is needed, only signs.
and the final code in Motors.pde, adding throttle and controlling total motor value not to get out of bounds, would be:
NOTE: If the sides where to be closer to each other, a roll value would have to be added, as they would have to have less strength than pitch; and viceversa, if you got your front and back motors closer, you would have to add a pitch value.作者: feitian227 时间: 2012-5-29 14:18
Octo classic mode
Next, Octo in classic mode, with one motor at front and back:
More in detail:
Motor Pitch Roll Yaw
0 Front CW +100% +0% -
1 FrontRight CCW +71% -71% +
2 Right CW +0% -100% -
3 BackRight CCW -71% -71% +
6 Back CW -0% -0% -
7 BackLeft CCW -71% +71% +
9 Left CW +0% +100% -
10 FrontLeft CCW +71% +71% +
Thus the resulting pseudo-code should have these signs and values:
Octo X mode
Next, Octo in "Quad" mode, 2 motors at the front, 2 at the back, 2 left and 2 right:
More in detail:
Motor Pitch Roll Yaw
0 Front CW +92% -38% -
1 Front CCW +92% +38% +
2 Left CW +38% +92% -
3 Left CCW -38% +92% +
6 Right CW -38% -92% -
7 Right CCW +38% -92% +
9 Back CW -92% +38% -
10 Back CCW -92% -38% +
To be able to have full power, I'll increase values to 100%, so proportionally they will be: 92% = 100% and 38% = 42%, thus giving these values:
Thus the resulting pseudo-code should have these signs and values:
FrontCW = + (1 * Pitch) - (0.42 * Roll) - Yaw
FrontCCW = + (1 * Pitch) + (0.42 * Roll) + Yaw
LeftCW = + (0.42 * Pitch) + (1 * Roll) - Yaw
LeftCCW = - (0.42 * Pitch) + (1 * Roll) + Yaw
RightCW = - (0.42 * Pitch) - (1 * Roll) - Yaw
RightCCW = + (0.42 * Pitch) - (1 * Roll) + Yaw
BackCW = - (1 * Pitch) + (0.42 * Roll) - Yaw
BackCCW = - (1 * Pitch) - (0.42 * Roll) + Yaw
and the final code in Motors.pde, adding throttle and controlling total motor value not to get out of bounds, would be:
FrontCW = constrain(throttle + control_pitch - (0.42 * control_roll) - control_yaw, minThrottle, 2000); // Front Motor CW
FrontCCW = constrain(throttle + control_pitch + (0.42 * control_roll) + control_yaw, minThrottle, 2000); // Front Motor CCW
LeftCW = constrain(throttle + (0.42 * control_pitch) + control_roll - control_yaw, minThrottle, 2000); // Left Motor CW
LeftCCW = constrain(throttle - (0.42 * control_pitch) + control_roll + control_yaw, minThrottle, 2000); // Left Motor CCW
RightCW = constrain(throttle - (0.42 * control_pitch) - control_roll - control_yaw, minThrottle, 2000); // Right Motor CW
RightCCW = constrain(throttle + (0.42 * control_pitch) - control_roll + control_yaw, minThrottle, 2000); // Right Motor CCW
BackCW = constrain(throttle - control_pitch + (0.42 * control_roll) - control_yaw, minThrottle, 2000); // Back Motor CW
BackCCW = constrain(throttle - control_pitch - (0.42 * control_roll) + control_yaw, minThrottle, 2000); // Back Motor CCW
Files to Check when adding new motor mixing
COMMS.pde (Show_Platform_Info())
Motors.pde (motor_output())
system.pde (APM_Init())
Well Pirates, that's about it, I hope I've been able to enlighten a bit more your pirte minds! Now you can go and design your own weird shape!!
I hope you got the idea!
any comments / addings / corrections are welcome!!
