Low cost MEMs accelerometers, gyroscopes and magnetometers --> 3D Posisition and attitude

Hi,

I am an amateur robotics fanatic and I need an expert advise.
I have a 3D accelerometers and three 1D gyros connected and a 3D
magnetic field sensor.
These sensors attached on to a carrier printed circuit board (PCB)  in
such a way that I can observe (by oscillascope) that their output
changes as I move/rotate the carrier board in 3D space.

Initially I leave the PCB in a predefined position on a table for
calibration. After that I move the PCB in 3D space and I want to
estimate the 3D position and orientation/attitude of the PCB at an
arbitrary time.

Assume that we have the following declerations to store the initial,
calibration values and the current values.

typedef struct {
   float AccV[3]; // Output voltages (AVx, AVy, AVz) of the
acceleormeters
   float GyrV[3]; // Output voltages (GVx, GVy, GVz) of the gyros
   float MagV[3]; // Output voltages (MVx, MVy, MVz) of the
magnetometers
}MeasStruct; // Measurements

typedef struct {
   float Pos[3]; // Position
   float Vel[3]; // Velocities
   float Acc[3]; // Acceleration
   float Att[3]; // Attitude (Roll, Pitch, Yaw  angles)
}PVAAStruct; // Pos,Vel, Acc, Att


MeasStruct CalibrationMeasurements;
PVAAStruct CalibrationPVAA;

MeasStruct CurrentMeasurements;
PVAAStruct CurrentPVAA;

long int T =0; // Time counter
int dT = 10; // Time increment in millisecond

void Init()
{
   CalibrationMeasurements.AccV[0] = ReadADC(AccVxChannel);
   CalibrationMeasurements.AccV[1] = ReadADC(AccVyChannel);
   CalibrationMeasurements.AccV[2] = ReadADC(AccVzChannel);

   CalibrationMeasurements.GyrV[0] = ReadADC(GyrVxChannel);
   CalibrationMeasurements.GyrV[1] = ReadADC(GyrVyChannel);
   CalibrationMeasurements.GyrV[2] = ReadADC(GyrVzChannel);

   CalibrationMeasurements.MagV[0] = ReadADC(MagVxChannel);
   CalibrationMeasurements.MagV[1] = ReadADC(MagVyChannel);
   CalibrationMeasurements.MagV[2] = ReadADC(MagVzChannel);

   CalibrationPVAA.Pos[0] = 0.0; // Position X
   CalibrationPVAA.Pos[1] = 0.0; // Position Y
   CalibrationPVAA.Pos[2] = 0.0; // Position Z

   CalibrationPVAA.Vel[0] = 0.0; // Velocities X
   CalibrationPVAA.Vel[1] = 0.0; // Velocities Y
   CalibrationPVAA.Vel[2] = 0.0; // Velocities Z

   CalibrationPVAA.Acc[0] = 0.0; // Acceleration X
   CalibrationPVAA.Acc[1] = 0.0; // Acceleration Y
   CalibrationPVAA.Acc[2] = 0.0; // Acceleration Z

   CalibrationPVAA.Att[0] = 0.0; // Attitude Rol angle
   CalibrationPVAA.Att[1] = 0.0; // Attitude Pitch angle
   CalibrationPVAA.Att[2] = 0.0; // Attitude Yaw  angle
}

void UpdateState()
{
   T = T + dT;
   CurrentMeasurements.AccV[0] = ReadADC(AccVxChannel);
   CurrentMeasurements.AccV[1] = ReadADC(AccVyChannel);
   CurrentMeasurements.AccV[2] = ReadADC(AccVzChannel);

   CurrentMeasurements.GyrV[0] = ReadADC(GyrVxChannel);
   CurrentMeasurements.GyrV[1] = ReadADC(GyrVyChannel);
   CurrentMeasurements.GyrV[2] = ReadADC(GyrVzChannel);

   CurrentMeasurements.MagV[0] = ReadADC(MagVxChannel);
   CurrentMeasurements.MagV[1] = ReadADC(MagVyChannel);
   CurrentMeasurements.MagV[2] = ReadADC(MagVzChannel);

   // How to calculate current Pos, Vel, Acc, Att values?

   CurrentPVAA.Pos[0] = ??; // Position X
   CurrentPVAA.Pos[1] = ??; // Position Y
   CurrentPVAA.Pos[2] = ??; // Position Z

   CurrentPVAA.Vel[0] = ??; // Velocities X
   CurrentPVAA.Vel[1] = ??; // Velocities Y
   CurrentPVAA.Vel[2] = ??; // Velocities Z

   CurrentPVAA.Acc[0] = ??; // Acceleration X
   CurrentPVAA.Acc[1] = ??; // Acceleration Y
   CurrentPVAA.Acc[2] = ??; // Acceleration Z

   CurrentPVAA.Att[0] = ??; // Attitude Rol angle
   CurrentPVAA.Att[1] = ??; // Attitude Pitch angle
   CurrentPVAA.Att[2] = ??; // Attitude Yaw  angle
}

}
int main()
{
   Init();
   while (1) {
     UpdateState();
     fprintf("Position=(%f, %f, %f), Attitude=(%f, %f, %f)",

CurrentPVAA.Pos[0],CurrentPVAA.Pos[1],CurrentPVAA.Pos[2],

CurrentPVAA.Att[0],CurrentPVAA.Att[1],CurrentPVAA.Att[2]);

   }
}

Question;
Can you show me/us how to calculate position and attitude estimates of
the PCB at any time step?
i.e. Can you help me how to finalise the UpdateState() function?


Regards,

Miem Chan
miemchan at gmail com