DIrection cosine matrix sequence question. Roll - pitch - moment.

Hello! When trying to first make a roll-pitch-moment and then another roll, it cannot convert the second transformation, the 3D plot goes into an unwanted direction.

[cosd(teta) 0 -sind(teta);[1     0         0     ;                              
0  cosd(phi) sind(phi);                                
0 -sind(phi) cosd(phi)]*
0       1        0   ;
sind(teta) 0  cosd(teta)]*Velocity_matrix=New_velocity_matrix

And then perform

[1     0         0     ;                              
0  cosd(phi) sind(phi);                                
0 -sind(phi) cosd(phi)]*New_velocity_matrix

it doesnt work but flips it with respect to inertial frame. Any suggestion? Kind regards

[Jan]

I assume something went wrong during typing the message: The first matrix contains another matrix. Is this intented? Use the "{} Code" button for formatting. Thanks.

Answer 1

[Jan]

The code does exactly, what is defined mathematically. If this moves the vectors in an "unwanted direction", you want to do something else - but we cannot guess what it is.

A frequent problem with rotation matrices is the definition, if the rotate the vectors or the reference frame. Both points of view are valid, but the results differ. Does applying the transposed rotation matrices satisfy your needs?