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EOH 2004 Project: Pinball

You've played pinball games on a computer before. What happens when the computer wants to play a real pinball game? We at SigArch have decided to find out. We're fitting a pinball machine with a camera, an embedded PC, and some relays to control the flippers so we can answer this age-old question.

The Machine

We've purchased a 1978 Bally Star Trek machine. Its brain is a MC6800 CPU with 4K of program ROM. Pictures of the machine can be found at the bottom of this page.

To control the flippers, we've put two relays in parallel with the normal switch mechanism. A PIC18F452 on the circuit board takes flipper commands over the serial port. It also serves to route messages from the serial connection to other boards, such as the board in the backbox which reads the current score from the machine.

A miniature video camera is suspended above the playfield where it can track the movement of the ball. It produces NTSC interlaced video at 60 fields per second suitable for capture with a TV capture card in a PC.

Image-processing and artificial intelligence algorithms run on a Linux PC inside of the pinball machine cabinet.

Currently, the machine plays pretty poorly. To finish the project for EOH, we hardcoded a lot of the AI algorithm, and therefore the machine doesn't make very intelligent decisions. We're currently working on an algorithm based on reinforcement learning to develop more intelligent behavior.

More Information

For those interested in duplicating this project, we have much more information available, including source code and schematics for some parts of the project.

Technical Details Page

Other Projects

We also plan to interface a magnetic card reader with the machine so the machine can keep records of players based on their university ID cards.

Demos

You can see a demo of an early version of our software in action. You'll need an XviD codec installed to watch the following video file. This video was created using the computer to track the ball and trigger the flippers. This build of the code was pretty dumb, but it's gotten better since then.

Demo Video (13MB)

Here's a newer version of the control software, running at the recent Siebel Center open house on April 30th, 2004. The monitor to the right of the machine shows what the computer sees, with the red dot representing where it thinks the ball is.

Another Demo (13MB)

Pictures

Here are some pictures of the machine. Click on the thumbnails for a full image:

Links

Bally Star Trek Manual

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