海面上失踪，他的关于声波导航的论点得到证明。

His point about sound navigation was rammed home by the disappearance of an aircraft over the sea.

每个机器人上装有声波导航和测距装置,这也使得它们不会碰撞到墙壁与其它的机器人.

Eight sonars on each unit helped them avoid collisions with walls and other robots.