Comb the Beach for Valuables with This DIY Metal-Detecting Robot

There is a good chance that you’ve managed to lose an item or two on a sandy beach, and you’re certainly not the only one. Florida alone gets more than 100 million visitors every year. It’s pretty safe to say that the vast majority of them are traveling to the state to go to either a theme park or one of the state’s world famous beaches. Predictably, a favorite pastime of beachgoers is metal detecting, and on every beach you will find at least a few people scouring the sand for lost valuables. If you want to get in on the action in a fun new way, you can build this fantastic Arduino-based, metal-detecting robot, complete with controller.

Metal detectors work by emitting a relatively strong electromagnetic (EM) field from a transmitter coil. If you’re close enough to a conductive piece of metal, that EM field will induce current in it. That, in turn, causes the piece of metal to emit its own (much weaker) EM field, which the metal detector’s receiver coil is capable of identifying. This robot works in exactly the same way, thanks to the small metal detector module that contains the necessary transmitter and receiver coils. That module is attached to the front of an otherwise straightforward rover-style robot that is constructed from 3D-printed parts. All of the part files and code for this project are available, so you can start creating the robot as soon as you purchase the electronic hardware.

Both the robot itself and the controller are built on an Arduino RF Nano board (available from a variety of online retailers). The most important addition to this Arduino clone is the nRF24L01+ RF transceiver module, which enables the remote control. The chassis of the robot and the enclosure for the controller are both 3D-printed. The robot is driven by four geared DC motors through a 1.2A motor driver. Power comes from a pair of 18650 li-ion battery cells. The remote control is also powered by two of the same cells. A pair of joysticks on the controller are used to control the robot’s throttle. A small LCD screen provides the status of the radio connection and a notification if the robot detects metal. This is a very affordable robot to make, and would be a fun project if you live near a beach or anywhere else where there are buried valuables to be found.