To avoid obstacles a HC-SR04 Ultrasonic sensor mounted on a SG90 Servo continuously scans the area. Manual control is by a GUI implemented with a Bluetooth HC-05 Module and the BlueDisplay library.

Or, you can buy an ultrasonic cleaning machine and let it do all the work instead. These countertop contraptions—which we have not tested—claim to dislodge food bits, bacteria, and the like ...

Ultrasonic sounds are high-frequency sound waves that exceed 20,000 hertz, making them too high-pitched for human ears to detect. These sound waves vibrate more than 20,000 times per second. Doctors ...