PMDS is a device that can determine whether a machine in front of the device is a perpetual motion machine. This is a gag invention, as by the second law of Thermodynamics, perpetual motion machines cannot exist.
The US Patent office automatically rejects any application that mentions "free energy" or "perpetual motion". This project aims to find out if they will reject a "perpetual motion machine detector" as well. It costs a lot to file a patent, by the way.
As far as I can tell, no one has ever tried to create such a device, probably because it serves no real purpose. Nevertheless, sell the shovels. Here is a link to a perpetual motion machine that has made it past the scrutiny of the US Patent office in 2006: https://patents.google.com/patent/US20070246939?oq=perpetual+motion+machine. It was later abandoned.
