One DOF Spinning Body Update Effector Mass Props

[seb-argo]

In SpinningBodyOneDOFStateEffector::updateEffectorMassProps we find the following code:

    // Find rPrime_ScB_B
    this->rPrime_ScS_B = this->omegaTilde_SB_B * this->r_ScS_B;
    this->rPrime_ScB_B = this->rPrime_ScS_B;
    this->effProps.rEffPrime_CB_B = this->rPrime_ScB_B;

Why is this valid? In particular, the second line, where B is being treated the same as S?

[joaogvcarneiro]

Because rPrime_SB_B is 0, as r_SB_B is fixed in the B frame.