\[\begin{equation}
\vec{p_{4N}}=
\left[
\begin{array}{cc}
\sum_{k=1}^N\left\{L\left(\cos\alpha_{2k-1}+\cos\alpha_{2k}\right)+h_1\cos\beta_{2k-1}+h_2\cos\beta_{2k}\right\}\\
\sum_{k=1}^N\left\{L\left(\sin\alpha_{2k-1}+\sin\alpha_{2k}\right)+h_1\sin\beta_{2k-1}+h_2\sin\beta_{2k}\right\}\\
\end{array}
\right]
\end{equation}\]
In case of all modules are same and \(L>>h_1,h_2
\), \(\phi\) can be calculated from (15),