[tmatrix]

Hi, everyone

I recently read the code of sixDoFRigidBodyMotion class. There is a function rotate in this class and the corresponding code is shown as following:

inline Foam::Tuple2<Foam::tensor, Foam::vector>
Foam::sixDoFRigidBodyMotion::rotate
(
const tensor& Q0,
const vector& pi0,
const scalar deltaT
) const
{
Tuple2<tensor, vector> Qpi(Q0, pi0);
tensor& Q = Qpi.first();
vector& pi = Qpi.second();

tensor R = rotationTensorX(0.5*deltaT*pi.x()/momentOfInertia_.xx());
pi = pi & R;
Q = Q & R;

R = rotationTensorY(0.5*deltaT*pi.y()/momentOfInertia_.yy());
pi = pi & R;
Q = Q & R;

R = rotationTensorZ(deltaT*pi.z()/momentOfInertia_.zz());
pi = pi & R;
Q = Q & R;

R = rotationTensorY(0.5*deltaT*pi.y()/momentOfInertia_.yy());
pi = pi & R;
Q = Q & R;

R = rotationTensorX(0.5*deltaT*pi.x()/momentOfInertia_.xx());
pi = pi & R;
Q = Q & R;

return Qpi;
}

I don't know why five rotation should be carried out in this function? Is there any comments for this treatment?

[mAlletto]

Did you find an answer? What's the exact reason to rotate in this order: first half angle around the x-axis, then half angle around y-axis, than the full angle around the z-axis, the half angle around the y-axis and last half angle around the x-axis?