Singing card concepts (1 GIF, 886 kBytes)
Mark Tilden's hand-written notes (c. 1990) on making interesting (if not terribly useful) devices from "junk" (in this case, singing greeting cards and liquid crystal displays)

Solarroller circuits (1 GIF, 269 kBytes)
Mark Tilden's hand-written notes (c. 1990)

Solarroller mechanics (1 GIF, 518 kBytes)
Mark Tilden's hand-written notes (c. 1990)

Vbug 1.5 / Walkman 1.0 (1 GIF, 585 kBytes)
Mark Tilden's hand-written notes on Vbug 1.5 (a.k.a., Walkman 1.0).

Walkman was constructed out of 4 "Walkman Pro" cassette recorders (in particular, the rectangular Escap MU915L motors from them) and an OTU gearmotor (for the waist). Walkman used a single battery, weighed 0.7Kg, had metal / plastic unibody construction, 2 visual and 5 tactile sensors, 8 sensor-processing Nu neurons, and 4 Nv neurons. Behaviors included high speed walking convergence, powerful environmental adaptive abilities, strong accurate phototaxis, 3 walking gaits (stop, walk, dig), and a backup/explore ability.

The legs on the motors had 360 degree freedom, which gave it great flexibility when trying different leg positions for climbing, pushing, and walking over different terrains. And there were rear-facing sensors, which made Walkman lift the corresponding rear leg somewhat higher than usual so it could clear whatever activated that sensor.

Sadly, all this is in the past tense, as Walkman was stolen out of Mark Tilden's Lab at the Los Alamos National Laboratories.

Vbug 1.6 / "Solar" (1 GIF, 206 kBytes)
Mark Tilden's hand-written notes (c. 1994)

Vbug 1.7 / "Walkman Daggerwrist" (1 GIF, 551 kBytes)
Mark Tilden's hand-written notes (c. 1994)

Walkman Daggerwrist is a highly adept 2 motor walking machine that has the skills to successfully negotiate very complex terrain. It also has a built-in 45 degree angle-of-attack sensor so it "backs down" from terrain that may be too hazardous.

Neural Voice Recognition (1 GIF, 76 kBytes)
Mark Tilden's hand-written notes (c. 1994)

Mark did some experiments with voice recognition a ways back. When asked about the circuit, he says that: "It's just a simple hipass/lowpass filter arrangement used in many voice recognition systems."