Lift - Base Design
The lift design was one of the most crucial and sensitive aspects of the LOBBYIST. We went through four prototypes before we had a design we were satisfied with. Our first two prototypes were extremely rough. One featured a form of 'soft skirt' and the other utilized a hard base. From these two prototypes we deduced that a hard base style design would be more consistent and would allow us better performance over hard and relatively smooth floors. 'Soft skirt' designs could handle a more uneven surface but took much longer to manufacture, had substantial amounts of body roll when cornering at speed, and were more sensitive to weight distribution and human error during manufacturing. Once our prototype proved that a hard base was capable of hovering on the floors in question, the decision to go with a hard base seemed obvious.
Our inspiration for our hard base design came from air hockey tables. We tried to mimic the thin film of air they create between our LOBBYIST and the floor. The third prototype we made utilized a simple flat base with holes that looked much like an air hockey table. While this worked on smooth surfaces, we found that our large foam core base bowed slightly thereby causing the prototype to get stuck on any uneven areas. In our final design, we utilized a thin center chamber in combination with a wide outer ring. The wide ring had strategically placed and sized holes to create lift while the pressurized center ring helped to lessen ground contact and even out pressure irregularities. This base design worked extremely well as our final design as it could glide over the most uneven areas in our lab and even some hard carpets.
Our inspiration for our hard base design came from air hockey tables. We tried to mimic the thin film of air they create between our LOBBYIST and the floor. The third prototype we made utilized a simple flat base with holes that looked much like an air hockey table. While this worked on smooth surfaces, we found that our large foam core base bowed slightly thereby causing the prototype to get stuck on any uneven areas. In our final design, we utilized a thin center chamber in combination with a wide outer ring. The wide ring had strategically placed and sized holes to create lift while the pressurized center ring helped to lessen ground contact and even out pressure irregularities. This base design worked extremely well as our final design as it could glide over the most uneven areas in our lab and even some hard carpets.
Lift - Pressurized Chamber
In order to create sufficient and even lift through the base design, the LOBBYIST needs to have a high pressure chamber of air directly above it. The lift fan used was specified by project requirements. A duct made out of foam core channels the air from the fan to a cylindrical chamber above the base plate. The duct is shaped such that it allows the air to gradually expand into the chamber, thereby minimizing pressure losses.
Propulsion
The Propulsion module contains an EPS-100C-BS brushed motor, a EP8060 propeller, and propeller guard made mostly of 1/8" duron. The front and back faces of the propeller guard are connected using 1 1/2" standoffs, with the resulting gap covered by duct tape. The motor and propeller are attached to the guard such that the propeller is safely confined inside of a protective cage. This prevents any wandering fingers from accidentally getting caught in the propeller.
In order to control of both thrust and direction, a total of two Propulsion modules are placed on the Lobbyist. Thus, by applying a similar thrust to both modules, the Lobbyist will go straight. If the thrust differ, the Lobbyist will turn.
In order to control of both thrust and direction, a total of two Propulsion modules are placed on the Lobbyist. Thus, by applying a similar thrust to both modules, the Lobbyist will go straight. If the thrust differ, the Lobbyist will turn.
The Display of Memory and Commitment (DMC)
The DMC consists of a magic lamp and an acrylic genie that is driven by a motorized linear potentiometer. When the LOBBYIST pairs with a PAC, the genie arises from the magic lamp. A strip of LEDs lights red or blue to indicate the team color of the PAC that paired with the LOBBYIST. Over time the genie slowly lowers back into the magic lamp. Once the 45 seconds has elapsed or the PAC unpairs with the LOBBYIST, the genie is fully retracted and the magic lamp lid is closed by a string also attached to the motorized linear potentiometer.
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Ball Hitting Swords
The LOBBYIST comes complete with two swords that swing out from the side of the hovercraft. The outward path of the swords effectively extends the reach of the LOBBYIST allowing it to be more effective in herding ping pong balls. The swords were powered by two small servos and were made to break off in the event of a hard collision with another LOBBYIST. During competition, these swords proved an effective means of quickly moving ping pong balls towards the desired goal.
Carpet
The carpet that we have placed on our LOBBYIST completes our 'flying carpet' LOBBYIST. We created a second level of foam core on our LOBBYIST and covered that level with the carpet. This level is great for looks as it hides all of our circuits and wiring, but it also serves as an extra layer of protection in the event of a collision. In order to make our flying carpet look even more realistic, we removed parts of foam core in the upper level thereby allowing the carpet to 'flap' slightly under the force of the propulsion fans.
lobbyist_assembly.pdf | |
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