),
    \end{eqnarray}
</p>
<p>As discussed above, it may be more convenient to use the states \(v_{\rm T}\) e \(\alpha_{\rm T}\) instead of \(\dot{x}\) e \(\dot{y}\). The respective time derivatives are</p>
<p>
    \begin{eqnarray}
    \nonumber \ddot{x} &=& \dot{v}_{\rm T} \cos \left( \psi + \alpha_{\rm T} \right) - v_{\rm T} \left( \dot{\psi} + \dot{\alpha}_{\rm T} \right) \sin \left( \psi + \alpha_{\rm T} \right) \\
    \ddot{y} &=& \dot{v}_{\rm T} \sin \left( \psi + \alpha_{\rm T} \right) + v_{\rm T} \l