On July 1 of the year 1898, Nikola Tesla filed U.S. Patent Application No.: 684,934 for a "Method of and Apparatus for Controlling Mechanism of Moving Vessels or Vehicles". The patent application would later issue on November 8, 1898 as U.S. Patent No.: 613,809. The '934 application disclosed a boat remotely controlled by radio waves. What makes this invention so amazing is that it was made early in the age of electricity and right at the dawn of radio, well before voice and other sounds could be transmitted by radio waves.
Tesla's remote-controlled boat looked more like a wash tub than a boat. It
had a narrow, tall hull that was fitted with an elongated and slighly bowed lid. A plurality of antennas and light posts protruded from the lid. Inside the hull, the boat contained a plurality of storage batteries connected to three electric motors. A large electric drive motor rotated a screw propeller, while two smaller motors controlled the lights and moved a rudder to steer the boat.
Tesla's remote-controlled boat looked more like a wash tub than a boat. It
had a narrow, tall hull that was fitted with an elongated and slighly bowed lid. A plurality of antennas and light posts protruded from the lid. Inside the hull, the boat contained a plurality of storage batteries connected to three electric motors. A large electric drive motor rotated a screw propeller, while two smaller motors controlled the lights and moved a rudder to steer the boat.
Most importantly, the boat had an electro-mechanical control system for controlling the motors. The control system was rather complicated and included a control battery, electromagnetic relays, switches and numerous mechanical components, including springs, cylinders, spindels, cog-wheels and eccentrics. The control system was constructed to perform a control routine comprising a fixed sequence of operations that an operator stepped through to control the boat. More specifically, there were four operations. In a first operation, the propulsion motor was started and the steering motor was controlled to move the rudder toward port. In a second operation, the steering motor was stopped and in a third operation, the steering motor was controlled to move the rudder toward starboard. In a fourth operation, the steering motor was again stopped. The control routine would then return to the first operation. The propulsion motor of the boat was stopped by holding the routine in the first or third operation for an extended period of time.
The component of the control system that moved the control routine from operation to operation was called a "sensitive device" and was essentially a wireless switch. The sensitive device included a cylinder that was connected between terminals of the control battery and contained metal particles and insulating films. The sensitive device was constructed to normally be non-conductive, but to have its insulating films under considerable stress from the applied battery voltage. When a radio signal in a particular frequency band was applied to the sensitive device, the metal particles moved together and the insulating films broke down, thereby allowing electric current to flow through the sensitive device and actuate a relay that moved the control routine to the next operation.
The radio signals sent to the sensitive device were generated by an interface device that was manipulated by the operator, who was located remotely from the boat. The device included a handle that was movabe in one direction through four positions. Moving the handle from position to position would transmit radio signals to the sensitive device, thereby causing the control system to perform the sequence of operations.
The component of the control system that moved the control routine from operation to operation was called a "sensitive device" and was essentially a wireless switch. The sensitive device included a cylinder that was connected between terminals of the control battery and contained metal particles and insulating films. The sensitive device was constructed to normally be non-conductive, but to have its insulating films under considerable stress from the applied battery voltage. When a radio signal in a particular frequency band was applied to the sensitive device, the metal particles moved together and the insulating films broke down, thereby allowing electric current to flow through the sensitive device and actuate a relay that moved the control routine to the next operation.
The radio signals sent to the sensitive device were generated by an interface device that was manipulated by the operator, who was located remotely from the boat. The device included a handle that was movabe in one direction through four positions. Moving the handle from position to position would transmit radio signals to the sensitive device, thereby causing the control system to perform the sequence of operations.
In order to woo investors, Tesla constructed a model of his remote-controlled boat and demonstrated it in the auditorium of the Madison Square Garden in September of 1898, as part of the first annual Electrical Exhibition. The model boat was constructed of iron and was about four feet long and three feet high. Tesla demonstrated the model boat in a large tank built in the center of the auditorium, which had been set up for special viewing for key investors like J.O. Ashton, George Westinghouse, J. P. Morgan and Cornelius Vanderbilt. Ever the showman, Tesla demonstrated the operation of his model boat by having audience members make requests for maneuvers that were then performed by the model boat in response to commands transmitted by Tesla through his interface device. The demonstration appeared to be the work of magic and caused a sensation.
After the demonstration, the Science Editor of the New York Times discussed with Tesla how the model ship could be used as a remote-controlled torpedo for destroying ships. Although Tesla had discussed such military use of his remote-controlled boat in the '934 patent application, Tesla must have been contemplating the broader meaning of his invention at that moment in time when he responded to the newspaperman that "You do not see there a wireless torpedo, you see there the first of a race of robots, of mechanical men which will do the laborious work of the human race".
After the demonstration, the Science Editor of the New York Times discussed with Tesla how the model ship could be used as a remote-controlled torpedo for destroying ships. Although Tesla had discussed such military use of his remote-controlled boat in the '934 patent application, Tesla must have been contemplating the broader meaning of his invention at that moment in time when he responded to the newspaperman that "You do not see there a wireless torpedo, you see there the first of a race of robots, of mechanical men which will do the laborious work of the human race".