Thursday, December 24, 2009

Merry Christmas and/or Happy Holidays

The robots and I wish you a Merry Christmas and/or Happy Holidays as applicable

Friday, December 18, 2009

Pyoony the mini robot


Ok, I admit that, lately, I've spent enough time building gadgets that are only peripherally related to robotics. Time to build another robot. This one is going to be scratch built from some reclaimed and repurposed hardware: a dual tape deck out of a dead all-in-one system (below, at top), motors from a broken linear tracking turntable (below, at bottom), and other goodies from a lifeless HP inkjet printer (not pictured).

The turntable mechanism features a pair of small motors that would be ideal for a differential drive robot. For wheels, paper rollers from the inkjet printer, driven by some combination of pulleys and gears from the tape deck. With two drive wheels I'll need at least one caster. The pinch roller mechanisms off the tape deck should do nicely. The recovered parts can be seen below.



So that's the start of the inspiration. Now, what the heck do I want this thing to do, how big should it be, how long should it run? Time to define the problem, that is, write down my requirements for the robot, in good systems engineering fashion.
  • Size: 3 cubic inches, maximum
  • Weight: light enough that the motors can drive it around on hard surfaces
  • Speed: no slower than 3 inches per second
  • Run time: 10 minutes or more
  • Behavior: this is a long story

I've had this ancient TAB book (#1241), How To Build You Own Self-Programming Robot, for 10 or 15 years and it was ancient when I got it. It was written in 1979! In short it presents a simple mechanism for a robot to learn how to react to external stimulus, primarily wall collisions. I'd kind of like to try out this scheme on Pyoony. Check out this website for a learning robot based on the book.

I am also interested in playing with the subsumption architecture. I can probably do both of these things if the robot is flexible enough. I'd also really love it if I could figure out a way for the robot to find its recharging station and recharge itself. Maybe that is asking too much.

In short I want the robot to sort of drive around in the living room on its own with some basic reflexes to guide it, and mostly keep it out of trouble. Sort of like a bug. Since we have four cats, I probably have no choice to but to figure out a way for it to survive feline aggression...

Thursday, December 17, 2009

Heathkit IO-12

As you can tell I haven't been up to much electronics tinkering lately. My efforts have all been focused on servicing old audio gear, like my friend's BIC 920 turntable, my TEAC A-7010 reel to reel deck, and so on. You think those are old?

They're youngsters compared to the Fisher 400 receiver and Knight KG-250 amplifiers I recently acquired and plan to refurbish. They use vacuum tubes (aka valves).

Before I dig into those beasties I want to practice on this old Heathkit IO-12 oscilloscope. Yeah, it uses tubes, too. It's simpler, more room to work inside, and so forth.

Part of the refurbish work involves replacing very old capacitors to avoid shorts, opens, and out-of-spec havoc.


To find bad capacitors, I could use the ESR test harness I wrote about... I just have to build it first.