def __init__(self, parent=None): super(CliffSensorFrame, self).__init__(parent) self._ui = Ui_cliff_sensor_frame() self._motion = TravelForward('/mobile_base/commands/velocity', '/odom', '/mobile_base/events/cliff') self._motion_thread = None self._distance = 1.2 self._state = CliffSensorFrame.STATE_FORWARD self._is_alive = False # Used to indicate whether the frame is alive or not (see hibernate/restore methods)