Niels's Posts

March 17, 2006




The Double Down card dealer is a fully programmable automated card dealer. It has the ability to deal a card in two directions (left or right, dealer or player, etc) while at the same time moving linearly perpendicular to those directions (card stack 1, 2, 3, etc).



Decent Back and Forth
Class Demo Day
Tech Demo Day 1
Tech Demo Day 2



The majority of the electrical work for this project was comprised of linear amplifier circuits to drive the DC motors. Each of the two motors had the following circuits created:


The V_in signal came from the PC/104 stack analog outputs driven from the computational model. The motors were each driven usen +/- 15V, but the stack could only output +/- 9V. Therefore, to push 9V up to the 15V source, the multiplier 5/3 (1.667) was chosen to push the limits. This would give us ultimate torque and speed.

The solenoids were also driven with a similar amplifier, though they only needed 12V.


Flipper & Scanner


Each playing card had a barcode printed onto each side, so that as it exits the stack the cuecat will scan it and know the card being dealt. This allows the robot to play any number of games rather than just deal them. The cuecat was disassembled into two parts. The black housing with the red light is the photodiode, LED and lens system for reading, and on the other side of the solenoid is the electronics that convert the signal into a keyboard signal. The cuecat was glued in place, and had to be positioned so that it was right against the surface of the barcode being scanned.

The Solenoid was included, but never fully functional in our project. For many games, some cards need to be dealt face up. The solenoids were added so that as the card is leaving the dealer the solenoid would kick up the back end of the card, flipping it over mid-air before landing on the table. The physical flipping worked quite well, but the actual timing of when to fire the solenoid was never implemented in out code, and is very difficult to do by hand.



The bulk of the body was constructed out of polycarbonate for its ease of machining and for viewing the internal mechanisms. Each piece was designed by hand, in SolidWorks, and then machined by hand in a mill. The pieces were glued together with a plastiweld glue and screwed together as well. The opaque pieces in the diagram represent pieces of UHMW for the bed and the axel bearings. UHMW was again chosen for its low friction, cost, and ease of use.


Another Maxon motor from the lab was used to control the movement of the cart. A 72:84 teeth ratio was used to gear down the motor for greater precision of movement. The gearing and the motor control gave very accurate and still rather fast movement. The gear ratio was chosen as it was the greatest ratio available given the physical constraints of the wheel size and distance between the motor and the axel.

March 16, 2006


bulk materials:

  • clear polycarbonate
  • blue UHMW (mcmaster)
  • aluminum stock

mechanical components:

  • springs (ace hardware)
  • shoulder bolts (ace hardware)
  • screws and set screws
  • Maxon motors (from the labs)
  • solenoids (jameco)
  • gears and hubs (robotzone)


  • cuecats (purchased from ebay)
  • PC/104 stack
  • resistors and transistors

if unlabled, the material was aquired from the shop

February 10, 2006

Project Proposal - Card Flipping

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

The following is taken from our project proposal:

1.2 Card Flipping

When dealing a game of blackjack, some cards need to be face-up and some face-down. When a card is dispensed from the deck housing is lying facedown and can be allowed to slide down a ramp and onto the table. So far we have thought of two different systems for flipping the card face-up before placing it on the table.

Figure 6: Flipping Method #1

The first method uses a foot that is lifted up by a small solenoid at the end to the ramp to prevent the card from falling onto the table. Then, a second solenoid pushes the top of the ramp while it pivots at the base. The foot will be an acute angle to hold the card in the ramp until it has been completely overturned.

Figure 7: Flipping Method #2
The second method uses a light sensor near the bottom of the ramp to trigger a solenoid at the top of the ramp, so that when the bottom of the card covers the sensor, the solenoid quickly pushed the top of the card out, flipping it in the air. A bar attached to the solenoid would ensure it flips the way we want. A light sensor makes most sense as a touch sensor might not be sensitive enough to feel something as light as a card.

Project Proposal - The Player/Card Recognition

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

The following is taken from our project proposal:

2 The player
Figure 3: Card’s Barcode

For our device to play any number of card games, it will need to know what cards it deals itself and sometimes which cards are dealt to the player(s). After considering several methods we agreed upon a barcode and phototransistor system, as it would be the simplest to implement in our design and doesn’t require metal contacts or stickers on the cards so that they remain slick for easier dealing.

2.1 Card Recognition

Using a template, a binary barcode will drawn on each card in opposite corners. The barcode will be composed of two parallel 6-bit binary numbers. The first set of lines will be all black and will act as the clock cycle for triggering the reading of the other set of lines next to it. The second set is then the one holding a binary number 1-52 for each card in a deck.

Figure 4: Methods for Sensing Barcode
An LED will light up the underside of the card and either one or two phototransistors will detect if the card reflects or absorbs the light. Two phototransistors can be used as digital inputs for reading the two lines, or one phototransistor can be used as an analog output to differentiate between no lines, one line, or two.
Figure 5: Sensor Position

The phototransistors and LED will be positioned at both outputs of the deck housing and will read the barcode as the card is dispensed. They can either be under a clear ramp that the cards slide down or in a recess of an opaque ramp.