Mark I was the first prototype of a series of autonomous airships built by the The Robot Group.
The airship utilized an undercarriage constructed of aluminum rods and plastic with two gimble-mounted toy motors driving two small propellers and a water ballast tank connected to an electric water gun pump. The gimble, powered by a geared-down Futaba hobby servo motor, was movable through one axis to provide multiple angles of pitch for the propellers.
The onboard control system was based upon a Motorola MC68HC11EVB development computer controlling the toy motors via relays and the Futaba gimble via Pulse-Width Modulated (PWM) signals. The control program generated movement based upon random selection of time intervals and movement selections.
The computer and motors were powered by a bank of generic NiCad batteries, providing power for an extended flight of approximately one hour. The ballast pump was operated by a radio-controlled mechanical switch.
The envelope for the Mark I was constructed of Mylar survival blankets taped together with Mylar tape. When inflated, the envelope measured approximately 6′ long x 4′ tall x 3′ wide. It carried a payload of approximately three pounds, roughly equivalent to the weight of the undercarriage and a handful of coins (additional ballast).
The Mark I airship was developed at a cost of approximately $200 and a time investment of approximately 50 man-hours. It was first exhibited at RoboFest 1 at Discovery Hall in Austin, Texas.
Problem areas were observed in the Mark I airship which would cause the retirement of the ship and redesign of a new airship. The problems that arose with the design included :
- The motors and propellers were not strong enough to overcome the slight indoor air system currents. When in flight, one could observe the program operating but could not associate the movement of the ship.
- Leaks in the envelope were significant. Even though the leaks were very small (most of them unidentifiable), ballast adjustment and refilling were constantly required.
- The random control program, even if the undercarriage provided stronger motive force, was disappointing, since the airship did not nearly imply coherent behavior.