Ultimate Machine

I decided to build a tribute to the "ultimate machine".
 

A popular image of a man of genius is of one who sits in a quiet office and thinks great thoughts, using only pencil and paper as his tools.  Exemplars include Einstein, Godel, and Erdos who revolutionized Physics, Logic, and Mathematics, respectively.  Einstein's "thought experiments" led to the Special and General Relativity, the very far reaching implications of which are still being tested and have always been confirmed.  With this kind of success, Platonic navel-gazing seems to be the certain path to knowledge.

But the 20th century has seen other non-Platonic examples of genius, exemplified by Feynman, Turing, Von Neumann, and Shannon, who have revolutionized their own fields (Physics in the case of Feynman, Computer Science and its related mathematics in the cases of the others).  These men made far-reaching theoretical contributions, but also were highly engaged in the practical world.  Feynman is famous for demonstrating in front of Congress that O-rings become brittle when cold by soaking one in ice water during his testimony, then snapping it in two (when testifying about the cause of the Challenger shuttle disastar).  Turing cracked German codes during World War II.  Von Neumann was a government contractor, living the high life and advocating a first strike on the Soviets.  Further, these men tended to be jokers. 

Shannon has a long and storied career.  His Masters thesis (see also here) showed how to reduce problems in designing switching circuits to Boolean logic - and is called the most important Masters thesis ever.  Later at Bell Labs, he developed "Information Theory", which (roughly) describes how information can be communicated.  Shannon was motivated by practical problems in cryptography (he worked with Turing) and signal processing, and developed a very far reaching theory which is the foundation of vast enterprises such as communications systems, data compression, and data mining (when you watch a video on youtube, you are using and being used by Shannon's theories in many many ways).

Shannon was also a prolific inventor of silly toys.  One famous toy was a mechanical mouse which could find its way through a maze (which he built in 1950).  After a first search through the maze, the mouse would move straight to its target.  This toy was a highly tangible demonstration of the power of switching theory, graph search algorithms, and machine learning.

Another toy is the Ultimate Machine, which does nothing but turn itself off.  The Ultimate Machine is a box with a switch in front.  Flip the switch to the On position, and a hand reaches out of the box to turn the switch off.  The Ultimate Machine is a joke about the nature of computation and the inevitable robot uprising.


I became interested in building an Ultimate Machine when Morris Odell posted a short note about one he had built to a very nerdy newsgroup that I read.  I asked him for more details and he was kind enough to send me a series of very detailed photos.  His version of the Ultimate Machine uses a "parallelogram linkage", which ensures that an arm raised by the linkage to a motor remains flat during the entirity of its motion.  I'd never heard of this before, being mechanically incompetent.  Morris' photos showed how he had machined the linkage parts himself.  Unfortunately, I live in a tiny Manhattan apartment and am not competent to operate machine tools.  I had to find a way to build a parallelogram linkage from parts I could find in a hardware store.

Fortunately, I did and it was fairly easy.  I picked up some aluminum bars and some "strap hinges".  I cut the aluminum bars, drilled holes for the strap hinges, screwed everything together, and it worked.  Below is a picture of the assembled machine clearly showing the parallelogram linkage at rest


The photo above shows a lot of parts of the Ultimate Machines.  After getting a paralleogram linkage to work, I needed to activate it somehow.  The bronze rectangle on the right hand side is a gear motor that came with an arm that screwed onto the output axle.  I need that large rotary motion to move the parallelogram linkage, but how?  I didn't even know the names of the parts I needed.  I searched around, then found the parts I needed on a RC hobby supply web site.  On the right hand side, connected to the motor arm, is a "ball linkage" : inside the plastic hood is a ball with a screw-hole drilled into it.  The ball attached to the motor arm and rotates freely with in the plastic hood. On the left hand side is a "clevis linkage".  Between them is 4-40 threaded rod.  Here is the linkage at nearly its most forward extension


An interesting aspect of the Ultimate Machine is that the box is a critical part of the machine.  It has to be of just the right height so that the hand is just hidden when the machine is off.  The ledge holding the switch has to start at a spot so that the hand just clears it on the ascent.  The switch itself has to be positioned so that the hand flips it at its maximum extension (I redid the ledge to move the switch further to the left).   On the topic of the switch, it is an exceptionally smooth action switch that I picked up at my favorite store in New York, Leeds Electric.

The logic behind an Ultimate Machine is simple.  Notice that there are two switches, the big obvious one at the upper left, and also a small limit switch on the lower right.  Move the hand forwards if the big switch is on, and backwards if the little switch is off and also the big switch is off.  A second joke of the Ultimate Machine is that this kind of switching logic was the topic of Shannon's master's thesis. I use a microcontroller to implement more complex logic, e.g., shut off power if the motor stalls.

I am completely incompetent at anything artistic, so I asked an artist friend, Yuliya Lanina, to make a hand for me.  I was expecting something totally conservative, a Caucasian hand in a dark suit sleeve.  I was shocked when she gave me a flourescent-white hand with blood-red nails.  She explained "it had to be weird" - please see her web site for more context.  But it worked out perfectly.  I had been thinking about building a totally conservative wooden box, but a black plastic box gives excellent contrast.  Also there is a third joke because it is a "black box".

Here is a video of the machine in action.