Comment by Michele on February 2, 2008 at 3:00am

wow!!, very, very compliments!!!

Comment by Jack Crossfire on February 8, 2008 at 5:23pm

Been 20 years since I saw "joy_x" in a piece of source code.

Comment by Christoph Prantl on March 31, 2008 at 5:37am

Hi Jordi,
I loke your work very much :-)
I'm pretty new in this UAV thingy and want to start with a project similar like your arducopter but make it a bit more "generic".

-> the part i'm trying to do currently is to try to use Kalman filters as "library" or external functions in the Arduino environment (i want to just pass values and get the corrected flattened values as response)
Do you have an earlier version of the Kalman filter code around somewhere? without the specific raedings and settings for your hardware.
Cheers Chris ...

3D Robotics Comment by Jordi Muñoz on March 31, 2008 at 10:40pm

Hello Chris,

Thanks for the compliment...

Yes i been working in a fuction like this:

Kalman(Gyro, AccelXY, AccelZ);

And the return will be the estimated position in radians... Is better because i save code for the two axis that i need to know (pitch and roll).

I have this for now, is the function:

float kalman (float q_m, float angle_m)
{

/* Unbias our gyro */
const float q = q_m - q_bias; //(Kalman)
const float Pdot[2 * 2] = {
Q_angle - P[0][1] - P[1][0], /* 0,0 */ //(Kalman)
- P[1][1], /* 0,1 */
- P[1][1], /* 1,0 */
Q_gyro /* 1,1 */
};

/* Store our unbias gyro estimate */
float rate = q; //(Kalman)

/*
* Update our angle estimate
* angle += angle_dot * dt
* += (gyro - gyro_bias) * dt
* += q * dt
*/
angle += q * dt; //(Kalman)

/* Update the covariance matrix */
P[0][0] += Pdot[0] * dt; //(Kalman)
P[0][1] += Pdot[1] * dt; //(Kalman)
P[1][0] += Pdot[2] * dt; //(Kalman)
P[1][1] += Pdot[3] * dt; //(Kalman)

R_angle= (joy_y_axis+1)*0.0098039; //external adjust jitter of accelerometer


float angle_err = angle_m - angle; //(Kalman)
float C_0 = 1; //(Kalman)
float PCt_0 = C_0 * P[0][0]; //(Kalman)
float PCt_1 = C_0 * P[1][0]; //(Kalman)
float E =R_angle+ C_0 * PCt_0; //(Kalman)
float K_0 = PCt_0 / E; //(Kalman)
float K_1 = PCt_1 / E; //(Kalman)
float t_0 = PCt_0; /* C_0 * P[0][0] + C_1 * P[1][0] (Kalman) */

const float t_1 = C_0 * P[0][1]; /* + C_1 * P[1][1] = 0 (Kalman) */


P[0][0] -= K_0 * t_0; //(Kalman)
P[0][1] -= K_0 * t_1; //(Kalman)
P[1][0] -= K_1 * t_0; //(Kalman)
P[1][1] -= K_1 * t_1; //(Kalman)
angle += K_0 * angle_err; //(Kalman)
q_bias += K_1 * angle_err; //(Kalman)



return angle*RadToDeg;
}


Good Luck!

3D Robotics Comment by Jordi Muñoz on March 31, 2008 at 10:43pm

Sorry my function is diferent you need to give the pitch or roll angle obtained just with the accelerometer:

angle_m= arcTan(axisX,AxisZ);

X= is for the pitch
Y=For the roll
Depends in the way you positioned your accel..

Comment by Christoph Prantl on April 1, 2008 at 2:49am

Hi Jordy,
Thank you so much ... I try to figure this out now.

Currently my only plan is to provide nick/roll stabilization (my 4 year old son wants to fly my heli :-))
and the gear is stabilized by a AVCS (Angular Velocity Control System) gyro anyway. And therefore i just want to use the Kalman filter for nick and roll "denoising".

Comment by Christoph Prantl on April 1, 2008 at 6:31am

I just set up a blog for the project:
Maybe you can take advantage of what I found out and did so far ... (of course with credits to all the people i use code of.)
I am going the "library" and function approach.

And the Heli i got is cheap and reliable for this :-)

Comment by Mitch on April 14, 2008 at 7:20pm

Thank you for your great work. I am going to use this as a base to make a Arduino IMU based on a Sparkfun 5DOF.

Comment by John Crisford on April 22, 2008 at 4:31pm

Will the bluetooth arduino be fast enough to get the data from sparkfun 6dof bluetooth and process through a kalman filter on 3 axis?

Comment by carmine on May 10, 2008 at 7:27am

hi.very good job. I think i need you. I'm doing a INS/GPS integrated positioning system with Kalman filtrer in C code for a little ship. Do you have somethingh for help me?
thank you very very much from Italy.

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