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Pucky 1.0 - Robot chassis with wheel encoder feedback

Pucky got his name once I'd finished assembling him. He looked like a big red hockey puck.

I wanted to experiment with drive motor control, so I needed a mobile platform to play with. I took this opportunity to search the web for inexpensive mobile robot platforms with wheel encoders. Tough luck... I didn't find any. I'd previously decided that I liked the Tamiya Dual Motor Gearbox, so I decided to add optical encoders to the gearbox. You can see the full evolution of this project on my [TMG Encoder] project page.

So, I had a motor drive with an encoder, now I needed a suitable chassis and controller to assemble my bot. I found [www.Pololu.com] who had great little circular acrylic chassis that was designed to mount the Tamiya gearbox. I ordered a couple of chassis', and got the matching "Ball Casters" to be the third-wheel. Since my encoder board is mounted to the top of the gearbox, I had to cut an opening in the chassis. I needed a hole that was approximately 1.5" x 1.5"

My old Scroll saw did fine cutting the access hole. In the picture to the right you can see the acrylic chassis with it's paper protection layer still attached. I left this in place while I marked and cut the opening. The Twin Motor Gearbox gets mounted under the chassis and the encoder board gets mounted on top. In the left picture I've removed the protective paper and mounted the gearbox and Ball Caster

Now I needed a controller board.

You may have guessed by now that I really like OOPic processor chip from [Savage Innovations], so I started hunting down a controller board that uses an OOPic process AND had drive logic capable of running two small motors. Eventually I came up with the OOBOT-40 processor from [Oricom Technologies]. The [OOBOT-40] is a great robotics board because it's really designed to be Uber configurable, plus it has two Quad H-Bridge Driver IC's. This means you could run four independent brushed DC motors. I only had two motors so I was fine.

The Pololu chassis come with lots of mounting holes, so I tried several configurations. Since I needed some extra height for a set of Sub-C rechargeable batteries, I used a second chassis as a space. Since this was just an experiment I wasn't too worried about the final appearance, but I still think Pucky looks cool. Click the picture for an enlargement.

Once I had Pucky up and running, I wrote an oUserClass object for him that would let me make use of the PWM motor drive and optical encoder feedback.