Older blog entries for gear21 (starting at number 3)

15 Apr 2002 (updated 15 Apr 2002 at 03:21 UTC) »

I spent a good part of the weekend ripping out all the power and ground connections and rebuilding and rewiring the entire system. (new pics coming soon)

There were a couple reasons for this... First, wires were starting to go everywhere (esp. with the connections from the switches), AND I needed to add another +5v source (just a 7805) since I didn't want to stress the OOPic now that it will connect to the IR ranger. It looks much cleaner now...

I also decided on a name for the bot! Akhenaten. (The 18th Dynasty Egyptian Pharoh).

10 Apr 2002 (updated 10 Apr 2002 at 05:21 UTC) »

After getting a few new bits and parts, I came up with a much more reliable bumper system... Instead of the overly-complicated spring/hinge mechanism, I converted it to a simple stip of aluminum bent at the ends and near the center. It's simple and works better! The pics of the bumper are on the bot's site at http://www.gear21.com/scook/bot/.

Some of you may have noticed that if it runs into something in the middle, it won't set off the left or right switch... but that's why I have the GP2D12 IR range module *GRIN*.

This week I soldered up the "secondary board" to my OOPic2 so I can attach the 40pin IDE connector to it without soldering my OOPic board. From the secondary board, I have 8 outputs (enable,fwd,rev, and PWM-speed for left and right) and 7 inputs (5 contact switches, 1 IR module, and 1 A2D for battery monitoring). BTW, solder flux RULES!

Since the switches are bolted to the outer shell of the bot, the connections are made to an IDC header, that I can connect the switches to. That way I can remove the shell without having permanent wires attached. Using the internal pullup resistors on the OOPIC is going to make the switch circuits really simple and clean.

I got a couple emails about the wheels and gear motors. I bought the motors from www.sciplus.com about 8 months ago. They were from one of the battery operated kiddy cars. The output shaft was unique in that it was 2.25" in diameter and was divided into 10 sections. I was originally going to just replace the shaft completly, but as luck would have it, by breaking off every other section, it fit exactly into my lawn mower wheels. (shell1.jpg shows the wheel). This was an astounding bit of luck that it matched size, radius, and depth! After that, I bought two more motors as spares!

2 Apr 2002 (updated 2 Apr 2002 at 22:26 UTC) »

Finally posted some pictures of my as yet un-named robot. There isn't an index yet, but they can be seen at: http://www.gear21.co m/scook/bot/

The skeleton is built from aluminum pieces scrounged from around work (which is why it is almost exactly the same size as a 12u rack-mount network switch :).

I used "off the shelf" DC motor controllers after many variations of H-Bridges I built just didn't have the flexibility I wanted... For the new controllers, I made a "universal interface" using cat5 ethernet cable and rj45 connectors, so I can swap out drive methods (from connected switches, remote control, to onboard microcontrollers).

Originally I was using a parallel port on a laptop to send signals to the motor controllers, but the laptop was just too big, so I got an OOPic a few weeks ago, and have started using it as the brains...

This week, I'm making an interface to the OOPic so I can connect 5 contact switches and 1 IR range module for external sensory duty...

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