Overview
Prototypes
PLAYER Hovercraft design
Hovercraft design included not only choosing the shape of the ship but also the material (something strong but lightweight) and the skirt type. A rectangular shape was favored over a circular one (in spite of fluid dynamics) to allow more room for electronics and batteries. The initial prototype had a plastic skirt, was made of cardboard reinforced with carbon fiber, and largely followed the instructions given here. The plastic skirt did not appear promising; it was difficult to maintain a strong seal. The following are prototypes that hovered much more reliably and are made with foam core.
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PLAYER Propulsion
To achieve steering and propulsion, we debated various fan positions, quantities, and steering mechanisms (mechanical ideas included rudders, ducting, etc.). As 218A/B veterans, we opted for the simplest proven option: two rear-mounted fans, PWM'd to achieve differential steering. A number of propulsion modules were explored, from 3D-printing ducts for use with cheap computer fans to sourcing RC plane propellers. Some examples are below. The driving specs included low current draw (4 A or less), high thrust, and simple implementation.
PLAYER Kicker
The PLAYER requires a kicker to engage with the soccer ball (a whiffle ball). The device cannot extend below the PLAYER's skirt without disrupting the air layer, so it necessarily will extend from the PLAYER. A few actuation concepts are discussed below.
One kicker design involves attaching a flipper to a servo. While being a relatively simple idea and easy to implement, it requires a fast and powerful servo for effective kicking as well as use of a PWM channel.
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Another kicker design involves attached a flat plate to the end of a solenoid. Using on/off control (and a return spring), the solenoid would punch out to deliver the kick. Although this idea has already been implemented in many RoboCup robots, it proved difficult to source a solenoid with reasonable voltage (<7V to avoid adding an extra battery) and sufficient throw.
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A variation of the solenoid idea uses a High Power Door Lock Actuator. This device provides push or pull (range is its throw) when the polarity across its leads is reversed. It is also a high-voltage option and requires an H-Bridge to switch the current safely. Unfortunately, it was difficult to source an actuator with sufficient throw for reasonable voltage and current.
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PLAYER Energy Level Indicator
The PLAYER is required to have an electro-mechanical display of its Energy Level. A preliminary sketch of a moving dial design is shown below.
COACH Controller Ideas
The COACH controller can be anything. Previous years have seen a Barbie car, a rocking horse, and a teddy bear among others. The idea is to engage the operator into wild, enthusiastic movements that may or may not make him or her feel or look foolish. Below are a few of our early ideas.