9. Ultrasonic Detection

This chapter delves into the workings of the ultrasonic sensor, an electronic module that senses the same way a bat does—with sonar. The sensor sends out pulses of inaudible sound, and then listens for them to bounce back, computing the distance traveled.

Ultrasonic sonars make excellent rangefinders, but can also be used to detect any kind of obstruction within its sensing area. Take Steve Hoefer’s Tacit project (grathio.com/tacit; see Figure 9.1). It’s a sonar for visually impaired people. It features a pair of Ping ultrasonic sensors paired with small servos that squeeze the wearer’s wrist when an obstruction is detected.

FIGURE 9.1 The Tacit glove squeezes when it detects an obstruction. Credit: Steve Hoefer.

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