William's Workbench

My cousin works for a school and spotted something on its way to the dumpster that he thought I might like.

He was right. (Thanks cuz!)

That is a SCORBOT-ER 4PC teaching robot, complete with controller and a PC with SCORBOT software. It’s amazing what some people will throw away. After getting this home, cleaned up, and up on the workbench for a look I discovered there was no cable to connect the PC to the control box.

Off to the webs I go and after waiting a few weeks for back order (nobody carries weird DB cables in stock these days) I had me a cable. Oops, it doesn’t fit. What at first glance I thought was a DD-50 connector was actually an HD-62. The cable from the control box to the robot is a DD-50 and I assumed the other was the same. Lesson learned, I should have counted the pins instead of assuming.

Fast forward a couple of weeks and a shiny new HD-62 cable arrives. Plug it in, boot up the ailing old Windows 98 PC (I really need to backup that HDD…) and I have a working robot. Wow. I’m in geek heaven. Now to bolt this thing to the workbench and teach it to solder…

My first SCORBOT program. Pick up a block and move it.

A closeup of the gripper.

Stacking some blocks.

Several years ago I got a good deal on a used Romba Discovery. A good cleaning and an AC adapter from the parts bin later it worked fine. The battery didn’t have much life in it after a few months of use so I bought another on eBay and all was well.

Fast forward a couple of years and the little robot had fallen into disuse but still sat patiently on its charger. Upon trying to start to use it again the battery gave out. After a charge it would give anywhere from 1 to 30 seconds of run time before flashing red and crying pitifully that it needed a charge. Some internet searching and forum reading led to a battery conditioning technique that is recommended by the manufacturer. I also took this opportunity to finally build a serial interface for the Roomba (more bits from the parts bin = $0 cost). Thanks to a few lines of Perl to parse the serial output and gnuplot I have pretty graphs of the battery charging cycle (that is currently 52 hours into the recommended 72 hours).

Click on the graphs to embiggen.

Here is voltage and current for the first 52 hours. You can see that the most interesting stuff happens in the first 17 hours.

Here is voltage/current and voltage/temperature for the first 17 hours. Something radical appears to happen around the 3 1/2 hour mark.

Hmmm, not sure what that means. Did the battery do something (possibly vent) due to heat? 40C isn’t all that warm but who knows.

After the 72 hours is up I will run the Roomba and see what kind of behavior I get.

Update

The battery did not respond to the reconditioning. One new battery from eBay later and the Roomba is back to normal.

http://www.jbprojects.net/projects/wifirobot/