def unpack_ROS_xform(xform):
    """ Unpack the ROS transform message into position and orientation """
    posn = [xform.transform.translation.x,
            xform.transform.translation.y, xform.transform.translation.z]
    ornt = [xform.transform.rotation.x, xform.transform.rotation.y,
            xform.transform.rotation.z, xform.transform.rotation.w]
    return posn, ornt