The Great Drivetrain Robbery - A True Story
April 1992
Kevin Dowling

--The Phone Call

Friday afternoon I'd been talking to some project team members
about project issues and the meaning of life. Usual conversations.
The phone rang. "Hello?"
"Hi Kevin, This is Mike. Something bad has happened"
"Uh-oh, what?"
"The drivetrain has been stolen"
"WHAT!!!?"

<fade to black>

--The Robot

We've been building a mobile robot, the Tessellator, for NASA`s
Kennedy Space Center (KSC) to work on the Space Shuttle. Tessellator
is designed to service the tiles on the bottomside of the Shuttle, or
Orbiters. The robot will perform inspections and also inject chemicals
into the tiles. The tiles are critical to the orbiter and protect the
it from the heat of re-entry into the Earth's atmosphere.

As a result of several factors the robot is relatively compact and
heavy. It is also amazingly maneuverable due to the incorporation of
some interesting wheels that allow the system to turn in place or move
in any direction. Building the robot has involved the design and
construction of high-quality, high-force drivetrains that connect a
motor, speed reducer and the wheel together. The drivetrain is a
chunky, powerful thing. When hooked up to our electronics and power
they are capable of driving our 2 1/2 ton robot over obstacles and in
any direction using our special roller wheels. We had an upcoming big
demonstration of the robot in May 1992 (4 weeks away from these
events) to demonstrate the system.

The motor is a special high-torque brushless motor, and the speed
reducer is a neat device called a cycloidial drive. It doesn't have
any gears like most speed reducers and transmission but has lobed
rollers and cams that provide very high speed reduction in a compact
and dense package.

The week prior to the phone call we had assembled our one and only
drivetrain to show some NASA people who came up to see progress on the
system. We not only showed it running and turning a wheel but later
dissected the drivetrain to point out assembly issues and illustrate
how the system worked and was put together. We hadn't really
thoroughly tested it at that point but the system had just come
together and begun to run. This process of running and disassembly
went well.

The core robot design team was myself, Hagen Schempf and Mike
Blackwell. I led the project and oversaw the design, Hagen was
responsible for the drivetrains and Mike was responsible for
electronics and hardware.

--The Current

During some early tests of the drivetrain, Mike noticed that the
drivetrain was drawing more current than it should be and surmised
that it might be the motor amplifiers but it also could be the speed
reducer. That is, he thought it was a mechanical issue. Hagen, who was
responsible for the drivetrain mechanics, of course thought it was the
electronics! The amplifiers take a signal from the computing hardware
and transform it into a high current, high voltage signal that is
porportional to the input. In this way, small input changes can
control powerful devices.

Mike contacted the local company that we had purchased the amplifiers
from and they concluded they should do some tests at their facility
north of Pittsburgh. Mike brought the core of the drivetrain to
them. This included the motor, speed reducer and the metal pieces
holding it all together. This core is a hefty 30kg and about 22cm in
diameter and about 35cm long.  It also represented at least $10,000 in
parts and machining alone.  The assembly was grayish in color and was
steel with a hard chromium coating. The color, gray, looked a lot like
aluminum. The motor sticking out the back was black and there were no
names or labels on the assembly.

Mike left it at the amplifier company so they could test the system
later that day and the next morning. They did some tests and found the
same symptoms we did; high current. Then they hooked up a really beefy
motor to drive the reducer. The bigger motor had trouble as well. From
this they determined that problem was not the amp after all, but that
the speed reducer was very stiff and hard to turn at room
temperature. As they ran the reducer it heated up and the lubricating
grease became more fluid and the system ran easier. The solution: we
needed to pack the reducers in oil and not grease. So, all in all,
good news and bad news. No showstoppers.

On Friday they ran some more tests and determined the relationship
between input force to turn the speed reducer and the temperature of
the unit. After many minutes of running it was finally at rated
specifications but the temperature was almost 100 degree Celsius! You
could boil water off the drivetrain! To start the next test require
cooling down the system and the easiest way was to put it outside
where it was a nice chilly motor-cooling kind of day.

They put the drivetrain on their loading dock at the back of the
building next to the door to their lab. It was covered with a cloth
and ropes were used to cordon off that corner of the loading dock. At
11:30am the engineer checked it again and it was still warm so he'd
thought he wait a little while and bring it then. A half-hour later he
came out and the drivetrain was gone!

--Panic, Hair-pulling and the Police

After quickly determining that no one at the company had moved the
drivetrain they tore the area upside down. Next door to the building
was a truck-driving school and they were approached to see if anyone
had seen anything. Other tenants in the building were questioned as
well. They emptied the nearby dumpsters thinking someone may have
accidently thrown it out. They looked in the cars, looked in bushes on
nearby roads... no luck, no drivetrain, despair... They called the
local police.

Mike had arrived at the company at about this time and found the
company people pulling the place apart. He then phoned me. After an
"April Fool's!" wasn't forthcoming I suggested that maybe someone
thought it was aluminum and took it to a recycler for money. 

After a time there Mike came back to CMU before the police arrived on
the scene...

--The Plan

We didn't panic but I wasn't taking any chances on the project and
immediately assumed we would never see the drivetrain again and worked
out a plan to create a new drivetrain out of spares. The tough part
was getting all the parts machined and getting one more speed
reducer. We'd already been subject to extreme delays in getting that
one speed reducer which was missing and it was the only one we had at
the time. Three others were due to arrive but we didn`t know if we
could get another. Hagen called that company and I called our
machinist at home to tell him that we would begin a bulding a new
drivetrain that weekend. We had four weeks til NASA showed up.

--Insult to Injury

I went to pick up Ashlinn, my daughter, from daycare and on the way
out tripped on some ice removal stuff. To avoid hurting Ashlinn I spun
and went down the steps landing on my back. Some knee pain but Ashlinn
was OK. What a day...

Hagen's in-laws were in town and we have design reviews, a conference
and demonstration to prepare for...sigh... Hagen's got ulcers - I
dunno what that's like but I was making some strong insightful
guesses.

I called the local police department and left a message for the
officer in charge of the investigation. He called back later and I
said I wanted to give him some photos if it would help. He agreed and
said he was onshift Saturday starting at 3:00pm. I said I'd get the
photos developed and then call him Saturday afternoon.

--The Evidence

That night, I came back into CMU to get a camera from Hagen's office
that had a picture of the drivetrain and shot the rest of the roll.

Saturday morning I brought the film to a Fotomat. One hour developing
took two hours...

Meanwhile from home I called CMU's Director of Public Relations at
home and told him what was going on and asked if I could get a contact
list for TV and Radio stations to contact. I figured that by having
words like "Space Shuttle", "Robots", "CMU", "Valuable" and "Theft" in
the same sentence that the local media would latch onto this story.  I
suggested that I would talk to the police officer first and see what
he had to say first. He agreed and said he would have the list for me
later that day.

The guy from the motor amplifier company called Mike at CMU and said
he hadn't slept Friday night. I called him and discussed the media
idea which he had also had. Again, I suggested waiting til I talked to
the officer that afternoon. If need be we could still be on the Sunday
night news with time to get on-site cameras to show the scene of the
crime.

I went to get the prints and only one of the pictures was useful.  It
showed the drivetrain on a table with the electronics around it and a
student in the background. I then went to have a dozen prints made. I
figured that I could have a courier service hit every scrapyard and
recycling center north of Pittsburgh on Monday morning with that photo
and a paper description and a no-questions-asked reward of several
hundred dollars.

After getting the prints I called the police station and the officer
returned my call finally around 5:30pm. We agreed to meet at a
restaurant parking lot at a major intersection a few miles from the
company at 6:00pm.

I highballed it there and showed him the photos and also brought a
drivetrain piece from one of the other assemblies to give an idea of
scale and weight. He also agreed that it might be someone who saw it
as scrap value and also thought that the media exposure was
worthwhile. He said because of the drivetrain's value and that 24
hours had passed that the crime was now Felony Theft. Sounded
like an impressive crime label to me.

I talked to the officer for a few minutes and then got back in my car
and decided to visit the scene of the crime. Mike had given me
directions and I had scribbled them on something that, of course, I
had left at home. I remembered them enough to find the place though.
I entered the small industrial park that the company was in. It was
about 6:30pm.

It looked like a small strip mall with a couple of associated larger
buildings. I didn't see the company immediately and drove down a dirt
alley to the back of the buildings. I noticed a couple of people
scavenging in a dumpster and a lot of old computer racks and frames
lying near the dumpster. I then saw the door and loading dock area at
the back of the amplifier company. It was more of a ramp than a
loading dock. It was also at least fifty feet from the dumpster so
there should have been no mistaking it for garbage.

I looked at the area for a few seconds and turned around and when back
to the people in the dumpster. They didn`t look like your average
dumpster divers. They were a young couple and drove a nice Audi.  I
figured it couldn't hurt to ask them...

I stopped my car and parked and went over to them and confronted the
guy with the photo and asked if by any chance he had seen this thing
the previous morning on the doorstep on the nearby building.

"Yah, I took it"

My heart leaped for joy and disbelief! I spun around happily and cried
"Alllright!  That's mine! You don`t know how happy I am to have found
you!"

He looked a little sheepish and said that he had seen it on the
loading dock and thought it was being thrown out. His girlfriend poked
her head out from the dumpster and said "He wouldn't have taken it if
he had known it belonged to someone!" I didn't argue with her logic, I
just wanted to get the drivetrain back.

While still pulling stuff out of the dumspter, he then asked if he
could get it back to me tomorrow or Monday.  "No way!" I cried, "I'm
following you home" I was on him like fleas on a dog til I got my
drivetrain back.

I talked to him a little while waiting for him to pack up. Jeff was a
graphic artist for an ad-agency on the second floor of the building
that the amplifier company was located in. He tinkered with stuff and
wanted to build animation stands and cameras and that's why he
scrounged stuff from dumpsters and loading docks.

I believe that Jeff wasn't malicious but he was naive and thoughtless.
He said he didn't see anyone to ask and so took the drivetrain. It
doesn't take much to see where this logic will lead.

I tailgated him home to Pittsburgh's Northside and dashed in the house behind
him. He had already taken the drivetrain apart the previous evening
but luckily had not taken the speed reducer apart. That would have
been very tricky to reassemble. I showed him the various pieces and
how they worked. I invited him down to CMU to see our labs and he was
clearly fascinated by our work. I thought maybe if he visits us we could move
his car elsewhere and say we didn't see anyone around it...

I called Mike, Hagen and the police station from Jeff's house. Mike
was entranced by the roller coaster ride we'd all been on and we all
remarked on the weirdness of the whole thing.  To quote a later
message he posted: 'Absolutely amazing.  The range of emotions, from
total disbelief, major embarassment, despair, and finally utter
relief. No one got much sleep last night...'

I had to hold the phone away from my ear as Hagen shouted
congratulatory things. Jeff and his girlfriend Gloria could see that
our team was happy.

I took the parts home and put them in my living room. I called out to
my wife Mary Jo "I've got the drivetrain!!!!" She replied, "oh, that's
nice..."  "NICE???" I cried. She burst out laughing.  Both Hagen and
Mike had called while I was driving home from Jeff's house.  I made
some more calls. The police officer called back later and said that
Jeff could be charged with Felony Theft. I said we weren't going to
press charges but I did give him Jeff's number.

Sunday morning I went to CMU again to get some more work done and Jeff
called to ask for a name at the amplifier company to apologize. He
also said the police had read him the riot act! He sounded genuinely
contrite but I didn't sympathize much.

Alls well that ends well for now. We'll put the drivetrain together
and have a Robot in May.

[Followup: We had a successful demonstration and a few laughs over the
Great Drivetrain Robbery. The Robot, with a lot more parts on it, was
finished and delivered to NASA in June 1994. The Drivetrains are
working fine.]

Kevin Dowling
April 1992