Instead, it relies on an ultrasonic distance sensor to detect a hand (or foot) waved in front of the door. An Arduino Leonardo runs the show, sounding a buzzer when the ultrasonic sensor is triggered.

To supply targeting data for the launcher, an Arduino Uno uses an ultrasonic sensor pair mounted atop a servo. As the servo rotates, the returns from the ultrasonic sensor are plotted on a screen ...

Arduino AI monitors noxious air bubbles via ultrasonic scans This one is an unusual smart home project, potentially - how to monitor a fish tank’s health with an AI-enabled ultrasonic sensor system.