@staticmethod
def interpolate(dq0, dq1, t):
    """Return interpolated dual quaternion

        Parameters
        ----------
        dq0 : skrobot.coordinates.dual_quaternion.DualQuaternion
        dq1 : skrobot.coordinates.dual_quaternion.DualQuaternion
            dual quaternion
        t : float
            ratio of interpolation. Must be 0 <= t <= 1.0.
        """
    if not 0 <= t <= 1:
        raise ValueError(
            'Interpolation step must be between 0 and 1, but gives {}'.
            format(t))
    dqt = dq0 * (1 - t) + dq1 * t
    return dqt.normalized
