Sensing sensors properly sensed....

All of the LEDs and phototransistors are now all completely installed in the wood-recessing blocks and completely soldered and connected to the sensing PCBs! Check out the photos that follow to see how the foosball table will roughly look during presentation.

Top of table showing all LED's and phototransistors installed
 in the wooden recessing  blocks along the parameter of the
table. Also pictured (right) is the LED/PT testing circuit we built to
test the sensors manually.

Another photo of the top of the table.

Furthermore, fabrication of the support table is complete and it's now in our lab! Thanks to Joe's dad for his expertise in carpentry and skillful implementation of our adjustable leg design! Pictures follow showing how the table will be setup once the slides arrive from Macron Dynamics.

Joe (left) and Ahmed (right) thinking about mounting heights of
equipment and a method of coupling the tables together during game-play.

Up close view of motor support table. The lateral motors will be mounted
horizontally on the support table.

Joe looking at the semi-finished product.

The PCBs are now mounted underneath the table and each of their multiplexer outputs has been marked and made ready to be connected to the BeagleBone. Once the BeagleBone is connected to the addressing pins of the PCBs and all the PCBs are connected together (via J3 and J4 connectors on the PCB to send power and the multiplexer address to each board), the BeagleBone will be used to automatically step through each sensing pair of LEDs/PTs along the parameter of the table and tell if there are any issues with sensors. The photos below show the interconnection of PCBs and wires coming from the output of each board to be used. This 'Z' output from the multiplexer (red wire) is used to tell the BeagleBone the location that the ball was last seen. See my earlier post about the sensing method if this is unclear.

Bryan (legs on the left), Khalil (middle), and Joe (right)
mounting the sensing boards along the bottom of the table
using 3M Command strips.

Mounted PCBs and multiplexer outputs (red wires) running
 to BeagleBone for testing the sensors.

Detailed look at where the 'Z' multiplexer output will go to the
BeagleBone. Later, there will be a hole made in the side of the table
to run the wires to the BB. 

Coming up:
1. A video of the BeagleBone output as we instruct the processor to test the sensors around the table.
2. BeagleBone motor control video.

Also, Team Foosbot will be giving a presentation on March 8th to show the latest progress to the faculty at the College of Engineering at the University of Akron. Wish us luck as crunch time rolls around!

Sensing PCB Design and Scheme explanation.

Pictured above is one (1) of twelve (12) PCB's furnished with our sensing scheme (comparators, resistors, a multiplexer, and a demultiplexer). These twelve boards will be connected together and used to detect the position of the ball as follows:

The LED's are pulsed in groups along the edge of the table. Corresponding to each LED is a phototransistor that sits across the table. When the LED is energized, the voltage across the phototransistor circuit changes. If the ball is to interrupt the infrared light going across the table, the voltage across the phototransistor circuit drops. This voltage (across the pull-down resistors in the phototransistor circuit) is compared with a reference voltage used in the comparator. The signals from all of the phototransistors are multiplexed and sent to the processor (BeagleBone Rev. A3), which demultiplexes said signals and locates the position of the ball based on the address of the phototransistor that detected the ball.

This process is repeated for sixteen (16) groups of phototransistor and LED pairs along the edges of the table to locate the position of the ball at a power-efficient and extremely fast rate. Once the position of the ball is found multiple times, a trajectory can be calculated and the position of the foosmen can be adjusted according to the future position of the ball.

Stay tuned for more updates related to the operation of the ARM processor on the BeagleBone development board as well as how motors will be used to position the foosmen and kick the ball!

-Khalil
Project Leader, Team Foosbot

Who is Team Foosbot and what are they building?

Need:
The game of foosball has entered the homes of people all over the world since it was first invented in 1922 to replicate the game of soccer.  The game was patented in the UK in 1923 and in the US in 1927 and remains as one of the oldest table games still played today, falling only to billiards and table tennis.  Today, five annual World Championship Series events are hosted by the International Table Soccer Federation (ITSF) which culminates in an annual World Cup where the best players from over 40 countries compete for world titles.  Even with the popularity of foosball, many tables remain highly unused, serving more as decorations than entertainment devices.  The automated foosball table would integrate modern technology with a classic game to provide entertainment to foosball table owners everywhere.


Team Objective:
The objective of this project is to design and build an automated foosball table machine which will serve as an opponent to a human player.  Besides providing the thrill of challenging a robot to a game of foosball, this also allow players to practice their skills when a human opponent is unavailable. The system will also keep score of the game for ease of play.  By doing so, the automated foosball table will provide an entertaining opponent for any game of foosball. Building this project on a senior-design team at the University of Akron will serve as the independent design requirement for the ABET accreditation.


Research Survey:

The concept of an automated foosball table has been explored by several groups, such as those from the University of Adelaide, the University of Sherbrooke, and the University of Waterloo.  Each design consists of different ways of detecting the position of the ball, moving the foosmen, and determining where to move the foosmen for game play resembling a human’s.  The program to control foosmen movement can be implemented on either a microprocessor or laptop computer.  This will need to communicate with the motors which need to be high-speed in order to accommodate real-time game play. 

Perhaps the most difficult aspect of the project is detecting the position of the foosball.  Several groups have used various types of cameras (high-speed, pin-hole) to track the ball.  These designs are very complex and extremely expensive. Team Foosbot thought of a much simpler and cost-effective approach to achieving the same thing. The idea is to use infrared light emitting diodes (IR LEDs) and optical detectors (phototransistors) so that the ball breaks the light from the LED.  This option allows for a very fast response, although the accuracy is limited since the LED’s must be placed far enough apart to prevent illuminating multiple photodetectors.

No patents for automated foosball tables were found. The only design found that resembles this tracking ability is a YouTube video that shows the reaction of the foosmen in response to the LED (visible light spectrum) tracking.

Updates:

Updates will be made on this blog as well as the following outlets:

Facebook group page (TeamFoosbot)

YouTube Channel: TeamFoosbot

Google+: TeamFoosbot

Twitter: TeamFoosbot

Add us/subscribe to our pages and channels/comment on our blog

More posts will be made shortly with updates related to the progress of the project.


-Khalil
Project Lead, Team Foosbot