The main problem of the ultrasonic sensor is the beam width.We conduced two different experiments to understand how accu-rate is this sensor. We need to understand how is its interceptionof obstacles on the lateral side with respect to the user. We usedtwo obstacles a 2D obstacle, a normal A4 paper sheet, and a 3Dobstacles, a carton box. The two obstacles were moved from the extremely right and extremely left of the sensor until the center to intercept the influence field of it, from a distance ranging from 0 to 150 cm.