Winter Break Update

Nate and I have been working until around 4AM every day this week on Robobuggy. Its been pretty stressful, but its still a lot of fun. We've accomplished a lot so far, but we still have a bit of ways to go.

A few nights ago, we took the buggy out on Forbes and on Morewood at around 2AM. Nate needed to gather data to ensure his algorithms were robust enough to work in the dark as well. There weren't many cars on the road, but the drivers that did see us pushing a buggy in the middle of the street must have been extremely confused. The drivers familiar with the area probably realized that this was typical CMU behavior.

The hardware aspect of Robobuggy is fairly small. There's one main computer that sits right in the middle of Robobuggy that controls all of its peripherals. A "phidgets" I/O Board hangs off of the main computer that controls and reads the data from the hardware components in parallel. The steering encoder runs through the I/O board as well as the hall effect sensor on the front wheel. In addition to the I/O board, there is a Servo controller that also plugs into the main computer via USB.

Although we do realize the analog camera that was on the old Robobuggy is still very good, its difficult to interface it with with our new computer brains. So instead, in true Nate Barshay image processing style, we replaced that camera with a Playstation Eye Toy (The Newer Version for PS3) . I could go into specifics of why we chose that camera, but the bottom line is that it was made for image processing. In addition, Playstation wants to push games instead of the EyeToy itself, so its pretty cheap for its value.

Two relays will control the braking valves. The relays are attached almost directly to the RC receiver, so we don't have to run the brake through the computer. In addition, the Robobuggy is set up in a way, that we can literally plug the steering servo into the RC receiver and steer it by remote control, pretty easily. We may do this in order to gather data more effectively.

3 6V Sealed Lead Acid Batteries will be powering the Robobuggy. I built an enclosure for them last night.

Some set-backs we've had:

We thought we could get away with building our own simple circuit for the quadrature decoder, turns out, its not that simple, and we need to buy specialized hardware in order to make that work.

The Hall Effect Sensor broke. I got new ones, all I have to do is attach them.

Nate's been chugging away with the code, and in our next update I'll provide a more detailed view on how the algorithms might work. Nate's having a bit of trouble with the methods being too slow, and he's working to fix that. In addition, I'll try to provide some stills from our sketchy night run.

Until next time,

Alex

The Next Two Weeks.....

As of right now, Nate has a pretty clear idea on how the navigation algorithm is going to work. Its essentially image processing algorithm coupled with navigation algorithms based on position, time and velocity, where the two algorithms play off each other depending which data is readily available. The buggy will rely on clues from its previous position and velocity, and make a guess as to where it is with a given confidence interval. If there is a white line available in the road, the confidence will increase. The buggy will compare its projected position on the road with a "map" of buggy course already in its brain. We predict that map will be represented as a string of GPS coordinates that trace a line through the track.

I have been working on the hardware and getting it all to interface with each other. There are circuit boards to print, and components to solder, so I definitely have all my work cut out for me. Right now I'm working on setting up the emergency brake to stop the buggy with an RC transmitter and integrating an I/O board to interact with a computer.

Nate and I will be in Pittsburgh working on Robobuggy until Christmas day. If you're in Pittsburgh - Stop by! We're at the corner house on Forbes and Morewood, the AEPi house.

-Alex