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CAPSTONE PROJECT: MULTI-MODE PORTABLE TURRET BLASTER

Capstone Project: Foldable Nerf Turret: Text

For the mechanical engineering capstone project, the course tasked us to form teams of 5 and identify and explore a market need, before designing a prototype for this need.

 

Our team, Team Wildcard, identified the need for a decent recreational foam blaster (eponymously known as “Nerf blasters”) that is meant to be used in a stationary manner. Competitor products identified in this niche were the Nerf Rhinofire and the Nerf Vulcan. The key deficiencies identified in these products were reliability issues and lack of uniqueness over conventional “mobile” blasters. Our solution was a “suitcase blaster”: a repeating blaster that can unfold from a compact container, and has multiple operating modes. By posting a survey on r/Nerf, we determined a group of other features that would be most desirable for our target user. 

 

The selected features were:

  • Easy to carry

  • Quick to deploy

  • Reliable firing (no jamming)

  • High ammo capacity

  • Manual control mode using handles

  • Bluetooth control mode using smartphone

Wildcard_Poster_24441.png

For our prototypes, we decided to use an off-the-shelf foam blaster, the Air Warriors Quantum, as opposed to designing a blaster from scratch, in order to demonstrate our prototype in action. This allowed us to focus our time and effort on aspects of the project that are most innovative. To control the blaster and switch between control modes, we used an Arduino Mega. To rotate the blaster, we decided to use a strong 20 kg-cm servo. Power was to be supplied by a Nerf Rival Rechargeable battery pack, but it was found that power also needed to be drawn from the pack of 6 D-batteries that came with the Quantum. We determined that in order to control the DC motors within the Quantum blaster, we would also need motor relays.


Our final iteration consists of a turret containing the blaster mounted on a base containing the Arduino, the two battery packs, the servo, and relays. Symmetrical carrying handles are attached to the base, and can be flipped down for deployment.

The mounting of the turret to the base consisted of a linkage that allowed the blaster to be lifted and rested in a raised position for manual control mode, or set down onto the rotation control boss for Bluetooth control mode. In manual control mode, the turret can be freely pivoted around the base upon a turntable bearing. For Bluetooth control mode, a wedge at the bottom of the turret that rests in a boss geared to the servo; the rotation of the boss would forces to the turret to rotate as well. The two modes are facilitated by two concentric turntable bearings.


The carrying handles are designed prevent the turret from rotating when folded up. They also served as a raised platform so that users would not have to crouch as low to use them. This double function was inspired by metal tennis hoppers. To y-shaped foot of the handles is designed so that they do not slip outwards when the weight of the blaster is resting on them.


The project was completed over the course of a semester. I served as overall project lead and was responsible for scheduling meetings, setting deadlines and goals, facilitating design discussions, and delegating design and manufacturing responsibilities. Components I was directly responsible for designing were the carrying handles, the mounting linkage, and the rotation wedge and boss.

Given more time, our team would have liked to implement foldable manual control handles (implemented ones were rigid), use of only one battery pack instead of two, and addition of autonomous operation using an Arduino-compatible camera.

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