Servo - June 2010

FIGURE 4. Rob’s test bed.

FIGURE 5. Melty board.

(a commercial version due to size). Motor control is via STMicroelectronics BU941ZT Darlington drivers, and the accelerometer is a Freescale 200G MMA2301EG.

Open Melt

The author, having rerun sufficient material to add pocket jingle without seriously enraging his editor, now begins to generate new material, at considerable more effort to himself …

Rich provides information on his robots and other projects at www.nothinglabs.com, and has now upgraded and refined the software into a fully open platform. He says: “I shifted from Bascom AVR to C (WinAVR) to eliminate the dependency on commercial software. The full version of Bascom AVR is about $130 — which is a lot

FIGURE 6. Death by Translation.

relative to the hardware for the project (which is only around $50-$100).” The code is licensed through Creative Commons to acknowledge his authorship. Rich also has posted a schematic (Figure 3), a tutorial video, and well documented code at

http://nothinglabs.com/nothing/ openmelt/.

Also on the site is a link to a centrifuge calculator, links to parts sources, and a video comparing wheel types. He feels someone with moderate electronics/microcontroller skills could build a test platform — similar to that shown in Figure 4 — in a weekend. The photo shows a test bed built by Rob Glidden, author of the companion article in this issue. He provides a nice segue into the next section, discussing how Rich’s brain melt has spread.

Open Melt is Contagious

Showing impressive literary skills, the author cleverly employs a “hook,” neatly tying this section to the eye catching article title …

Rob took Rich’s ideas and went a step farther down the road. He used Rich’s original Basic code as a reference; I’ve done all of my work using custom circuit boards and programmed in C. He says: “There are some neat tricks one can do to get more out of the Melty bot (control wise) but the biggest problem with putting a Melty bot in combat is making sure the insides stay where you put them — especially during hits!” Kevin Barker collaborated with Rich to build a Featherweight ( 30 pound) combat bot. Kevin did the hardware; Rich did the electronics. They used an impressive S28-150 Magmotor, two HFS33 solid-state relays, an MMA2301, 200G accelerometer, and a Pololu Baby Orangutan B-328 microcontroller. The bot — “Death By Translation” — was a creative success but a combat casualty. Kevin says: “The bot actually did not work very well. It spun plenty fast but due to a couple factors, it didn’t translate very well. It also was not strong enough to absorb its own impacts and bent several frame pieces in a huge hit with Touro Feather.” Figures 5 and 6 show the custom electronics board and the finished bot. Many more pictures are available at www.teamvelocityrobotics.com.