Double Down

This entry contains the continuation of our project propsal, found here.

The following is taken from our project proposal:

1 The Dealer

The cart has 4 wheels, powered by a DC motor, and rolls along a straight path of approximately 1-2 feet. As it rolls, the machine deals out the necessary cards for blackjack: the dealer’s 2 cards, the user’s 2 cards, and any additional “hits”. The DC motor is equipped with an encoder to determine where to deal the cards such that they are evenly spaced and do not overlap.

To prevent the cart from rolling off a table, it is equipped with an infrared range sensor on each end that will detect the difference between the tabletop and the floor. In the event the IR ranger detects the edge of the table, the machine will stop moving and produce an error signal or message.

The main component of the cart body is the storage bin for the cards. We intend to play with 2 to 4 decks, which will rest on a spring-loaded bed. This spring lifts the deck as cards are dealt, keeping the top card at a constant height for dealing. By dealing from the top of the deck, there is less weight on the card being dealt, thus reducing friction and enabling a more reliable deal. To deal from the bottom of the deck places the entire weight of the deck on the dealt card, increasing friction. Additionally, dealing from the top follows standard casino rules.

To lift the deck, the spring must simply be able to exert a force slightly larger than the weight of the deck. As cards are removed from the deck, the weight will lessen and the deck will become thinner. Accordingly, the spring will lengthen, given the extra space, and will exert less force (by Hooke’s Law) as the spring nears its natural length. Thus, by carefully selecting a spring with the appropriate length and spring constant, we can expect the top card to always be in the correct position for dealing, with the correct amount of force acting on it.

The cards are dealt using a rubber flap attached to a belt driven by a DC motor. The motor drives the belt clockwise or counterclockwise, depending on whether the card is being dealt to the user or computer. The rubber flap, selected to have a very high coefficient of friction, moves around the belt until it contacts the top card. As it continues along the belt, the flap drags the top card off the deck, since the flap/card friction will be considerably higher than the card/deck friction. Also, by using a single flap to contact the card, none of the other cards below will be touched or moved, which could potentially jam up the dealer. To reduce friction further, we are investigating the use of a small CPU fan to create a thin air pocket between the top card and deck.