def METHOD_NAME(self):
    ts = [0]
    us = []
    for i in range(self._ss.shape[0] - 1):
        us.append(
            0.5 * (self._xs[i + 1] - self._xs[i]) / (self._ss[i + 1] - self._ss[i])
        )
        ts.append(
            ts[-1]
            + 2
            * (self._ss[i + 1] - self._ss[i])
            / (self._velocities[i] + self._velocities[i + 1])
        )
    self._ts = np.array(ts)
    self._us = np.array(us)