超声波具有方向性好，穿透能力强，易于获得较集中的声能，根据超声波这些特性进行障碍物有效距离的探测已在很多领域得到应用。-Ultrasound is a good direction, penetration, easy access to more focused sound energy, according to these characteristics of ultrasonic obstacle detection and effective distance application in many fields.