Alter Fight Controller for Motor thrust around z-axis

Lynxmotion UAVs / Drones
1

Hello. New here and to Drone Tech. For a school project, we are launching a payload on a weather balloon up to 100,000ft. We are testing motors, props, and other equip in this extreme environment. Our payload will be hanging on the flight string at the bottom. We have attached 2 motors on booms on the L/R sides. They will be used to control the spin of the payload and stabilize in a desired direction.
I have attached an example drawing of our payload.

The problem I have is with preset configurations for the multicopter. I am using a Lynxmotion Quadrino Nano for the FC. I would like to edit or create a new type with 2 motors in the vertical configuration (no servo control, just using throttle of motor to turn). I see places in the MultWii code for the different copter types but am unsure what to change. I would just like to be able to use the Magnitometer and other sensors to orientate in a certain direction.

I have tried changing the sensor orientation to make up for the 90degree change in the motor mounting direction, but still have no luck. Any ideas or thoughts would be welcomed!

Thanks,

Simple BalloonSAT Drawing.jpg
Simple BalloonSAT Drawing.jpg933×628 20.9 KB

2

Hi,

There is a define in “config.h” which allow you to create a custom mixing:

//#define MY_PRIVATE_MIXING "filename.h"

In “Output.ccp” you will find all of the defines:

[code]
/**************** main Mix Table /
#if defined( MY_PRIVATE_MIXING )
#include MY_PRIVATE_MIXING
#elif defined( BI )
motor[0] = PIDMIX(+1, 0, 0); //LEFT
motor[1] = PIDMIX(-1, 0, 0); //RIGHT
servo[4] = (SERVODIR(4,2) * axisPID[YAW]) + (SERVODIR(4,1) * axisPID[PITCH]) + get_middle(4); //LEFT
servo[5] = (SERVODIR(5,2) * axisPID[YAW]) + (SERVODIR(5,1) * axisPID[PITCH]) + get_middle(5); //RIGHT
#elif defined( TRI )
motor[0] = PIDMIX( 0,+4/3, 0); //REAR
motor[1] = PIDMIX(-1,-2/3, 0); //RIGHT
motor[2] = PIDMIX(+1,-2/3, 0); //LEFT
servo[5] = (SERVODIR(5, 1) * axisPID[YAW]) + get_middle(5); //REAR
#elif defined( QUADP )
motor[0] = PIDMIX( 0,+1,-1); //REAR
motor[1] = PIDMIX(-1, 0,+1); //RIGHT
motor[2] = PIDMIX(+1, 0,+1); //LEFT
motor[3] = PIDMIX( 0,-1,-1); //FRONT
#elif defined( QUADX )
motor[0] = PIDMIX(-1,+1,-1); //REAR_R
motor[1] = PIDMIX(-1,-1,+1); //FRONT_R
motor[2] = PIDMIX(+1,+1,+1); //REAR_L
motor[3] = PIDMIX(+1,-1,-1); //FRONT_L
#elif defined( Y4 )
motor[0] = PIDMIX(+0,+1,-1); //REAR_1 CW
motor[1] = PIDMIX(-1,-1, 0); //FRONT_R CCW
motor[2] = PIDMIX(+0,+1,+1); //REAR_2 CCW
motor[3] = PIDMIX(+1,-1, 0); //FRONT_L CW
#elif defined( Y6 )
motor[0] = PIDMIX(+0,+4/3,+1); //REAR
motor[1] = PIDMIX(-1,-2/3,-1); //RIGHT
motor[2] = PIDMIX(+1,-2/3,-1); //LEFT
motor[3] = PIDMIX(+0,+4/3,-1); //UNDER_REAR
motor[4] = PIDMIX(-1,-2/3,+1); //UNDER_RIGHT
motor[5] = PIDMIX(+1,-2/3,+1); //UNDER_LEFT
#elif defined( HEX6 )
motor[0] = PIDMIX(-7/8,+1/2,+1); //REAR_R
motor[1] = PIDMIX(-7/8,-1/2,-1); //FRONT_R
motor[2] = PIDMIX(+7/8,+1/2,+1); //REAR_L
motor[3] = PIDMIX(+7/8,-1/2,-1); //FRONT_L
motor[4] = PIDMIX(+0 ,-1 ,+1); //FRONT
motor[5] = PIDMIX(+0 ,+1 ,-1); //REAR
#elif defined( HEX6X )
motor[0] = PIDMIX(-1/2,+7/8,+1); //REAR_R
motor[1] = PIDMIX(-1/2,-7/8,+1); //FRONT_R
motor[2] = PIDMIX(+1/2,+7/8,-1); //REAR_L
motor[3] = PIDMIX(+1/2,-7/8,-1); //FRONT_L
motor[4] = PIDMIX(-1 ,+0 ,-1); //RIGHT
motor[5] = PIDMIX(+1 ,+0 ,+1); //LEFT
#elif defined( HEX6H )
motor[0] = PIDMIX(-1,+1,-1); //REAR_R
motor[1] = PIDMIX(-1,-1,+1); //FRONT_R
motor[2] = PIDMIX(+ 1,+1,+1); //REAR_L
motor[3] = PIDMIX(+ 1,-1,-1); //FRONT_L
motor[4] = PIDMIX(0 ,0 ,0); //RIGHT
motor[5] = PIDMIX(0 ,0 ,0); //LEFT
#elif defined( OCTOX8 )
motor[0] = PIDMIX(-1,+1,-1); //REAR_R
motor[1] = PIDMIX(-1,-1,+1); //FRONT_R
motor[2] = PIDMIX(+1,+1,+1); //REAR_L
motor[3] = PIDMIX(+1,-1,-1); //FRONT_L
motor[4] = PIDMIX(-1,+1,+1); //UNDER_REAR_R
motor[5] = PIDMIX(-1,-1,-1); //UNDER_FRONT_R
motor[6] = PIDMIX(+1,+1,-1); //UNDER_REAR_L
motor[7] = PIDMIX(+1,-1,+1); //UNDER_FRONT_L
#elif defined( OCTOFLATP )
motor[0] = PIDMIX(+7/10,-7/10,+1); //FRONT_L
motor[1] = PIDMIX(-7/10,-7/10,+1); //FRONT_R
motor[2] = PIDMIX(-7/10,+7/10,+1); //REAR_R
motor[3] = PIDMIX(+7/10,+7/10,+1); //REAR_L
motor[4] = PIDMIX(+0 ,-1 ,-1); //FRONT
motor[5] = PIDMIX(-1 ,+0 ,-1); //RIGHT
motor[6] = PIDMIX(+0 ,+1 ,-1); //REAR
motor[7] = PIDMIX(+1 ,+0 ,-1); //LEFT
#elif defined( OCTOFLATX )
motor[0] = PIDMIX(+1 ,-1/2,+1); //MIDFRONT_L
motor[1] = PIDMIX(-1/2,-1 ,+1); //FRONT_R
motor[2] = PIDMIX(-1 ,+1/2,+1); //MIDREAR_R
motor[3] = PIDMIX(+1/2,+1 ,+1); //REAR_L
motor[4] = PIDMIX(+1/2,-1 ,-1); //FRONT_L
motor[5] = PIDMIX(-1 ,-1/2,-1); //MIDFRONT_R
motor[6] = PIDMIX(-1/2,+1 ,-1); //REAR_R
motor[7] = PIDMIX(+1 ,+1/2,-1); //MIDREAR_L
#elif defined( VTAIL4 )
motor[0] = PIDMIX(+0,+1, +1); //REAR_R
motor[1] = PIDMIX(-1, -1, +0); //FRONT_R
motor[2] = PIDMIX(+0,+1, -1); //REAR_L
motor[3] = PIDMIX(+1, -1, -0); //FRONT_L
#elif defined( FLYING_WING )
/*********** FLYING WING *********/
if (!f.ARMED) {
servo[7] = MINCOMMAND; // Kill throttle when disarmed
} else {
servo[7] = constrain(rcCommand[THROTTLE], conf.minthrottle, MAXTHROTTLE);
}
motor[0] = servo[7];
if (f.PASSTHRU_MODE) { // do not use sensors for correction, simple 2 channel mixing
servo[3] = (SERVODIR(3,1) * rcCommand[PITCH]) + (SERVODIR(3,2) * rcCommand[ROLL]);
servo[4] = (SERVODIR(4,1) * rcCommand[PITCH]) + (SERVODIR(4,2) * rcCommand[ROLL]);
} else { // use sensors to correct (gyro only or gyro+acc according to aux1/aux2 configuration
servo[3] = (SERVODIR(3,1) * axisPID[PITCH]) + (SERVODIR(3,2) * axisPID[ROLL]);
servo[4] = (SERVODIR(4,1) * axisPID[PITCH]) + (SERVODIR(4,2) * axisPID[ROLL]);
}
servo[3] += get_middle(3);
servo[4] += get_middle(4);
#elif defined( AIRPLANE )
/ AIRPLANE **************************************/
// servo[7] is programmed with safty features to avoid motorstarts when ardu reset…
// All other servos go to center at reset… Half throttle can be dangerus
// Only use servo[7] as motorcontrol if motor is used in the setup */
if (!f.ARMED) {
servo[7] = MINCOMMAND; // Kill throttle when disarmed
} else {
servo[7] = constrain(rcCommand[THROTTLE], conf.minthrottle, MAXTHROTTLE);
}
motor[0] = servo[7];

// Flapperon Controll TODO - optimalisation
int16_t flapperons[2]={0,0};
#if defined(FLAPPERONS) && defined(FLAPPERON_EP)
int8_t flapinv[2] = FLAPPERON_INVERT;
static int16_t F_Endpoint[2] = FLAPPERON_EP;
int16_t flap =MIDRC-constrain(rcData[FLAPPERONS],F_Endpoint[0],F_Endpoint[1]);
static int16_t slowFlaps= flap;
#if defined(FLAPSPEED)
if (slowFlaps < flap ){slowFlaps+=FLAPSPEED;}else if(slowFlaps > flap){slowFlaps-=FLAPSPEED;}
#else
slowFlaps = flap;
#endif
flap = MIDRC-(constrain(MIDRC-slowFlaps,F_Endpoint[0],F_Endpoint[1]));
for(i=0; i<2; i++){flapperons* = flap * flapinv* ;}
#endif[/code]**

3

Thanks for the reply. I did see the custom mixing option, but is unsure how to define for the motors being turned 90 deg.

4

What do you plan to achieve in term of stabilisation ?
There are two motors which only goes in one direction ? That will make you turn in circle no ?

5

Thanks Eric.

The motors go in opposite directions (Sorry if the arrows are missleading). As the balloon goes up the flight string twists back and forth, which turns the payload all around the z axis. I am looking to counter these forces using two motors. As it twists in one direction that motor spins up faster to counter the spin. I would like to point in any cardinal direction I choose. (We will have a Irridum Satellite modem that we can communicate to onboard, so I possibly could have it turn and face another direction mid flight) I currently have it kinda working by using the quad + copter type and only motors 6 & 5. I have mounted the Quadrino Nano vertically with the arrow up. It will self stabilize in what ever direction it is held in for a moment. This is definitely not the best way to have it done. I am unsure how to create a custom mixing option for this type of motor layout or if that is the best option. I am about avg in arduino code but have never used drone hardware. Any advice or ideas would be great. I have attached a pic of the temporary rig. The hardware will be incased.

Thanks again!

20170417_141835.jpg
20170417_141835.jpg5312×2988 3.98 MB

6

The Quadrino Nano using MultiWii will require an Input from a R/C system to work.
It will then try to Stabilize based on different sensors and Modes set in the WinGUI.

One option might be to use the “Wing” mode which control two servos (usually) for the control surface.