Quaternion conversion in satellite attitude using sun-earth sensors simulation

[shakeel001]

I need to convert quaternion (q) to a form that is suitable to show changing attitude of a Satellite. like new x,y,z vectors of a satellite.I don't know the math of quaternions. I am getting updated state using rung -kutta 4 method where state vector x=[q(1:4) wx wy wz a(1:3) b(1:3)].I can convert quaternion to euler angles but don't know further how to convert these to x,y,z of a satellite(updated) which will tell x,y,z position of a satellite after its state vector(x) was updated.

the sequence of operations I am doing are
% Simulation data
% Spacecraft data
% Gyro data
% Sensor data.
% Control system initialization
% Generate the orbit
% el = [a,i,W,w,e,M]. The spacecraft is in geostationary orbit
% Initial conditions at equinox
% Sun and Earth vectors
% Run the simulation

here I am using RK4 for solving differential equation which is giving me an updated state vector x​

% Attitude Determination

here I am getting q​

% Plot results


I shall be very grateful to all for help in this regards

Thanks again in advance for your time and efforts

 

[lippyka]

.The way to convert quaternion (q) to x,y,z vectors of a satellite depends on the type of quaternion you are dealing with. If it is a unit quaternion, then you can simply use the q2dcm function in MATLAB to convert it to a rotation matrix. From there, you can apply the rotation matrix to the initial x, y, z vectors of the satellite to get the new x, y, z vectors. If it is not a unit quaternion, then you can normalize it first before doing the q2dcm conversion.