Monday, June 3, 2013

Archive 100 GB for $1.00

I'm still processing images from my trip, oops. I also realized I have no hard drive space for the images, so I thought about how to remove all of my old images from primary storage and put them into backup. At first I considered Dropbox, but the rate of $100/year for 100 GB is pretty crazy, considering that the images that I'm uploading will probably only be accessed once a year, if that.

Instead, I'm using Amazon Glacier, which is relatively new AWS product designed for "secure and durable storage for data archiving and backup" and "optimized for data that is infrequently accessed and for which retrieval times of several hours are suitable." The most compelling aspect of the service to me is that the storage cost is $0.01/GB/Month currently. Additionally, there is no cost to transfer data in, and the cost to transfer data out is $0.12/GB, with the expectation that only 5% of the data will be accessed per month, and $0.13/GB exceeding that (if I am interpreting the sometimes confusingly complicated AWS pricing rules correctly).

Right now I'm uploading my ~60 GB archive of camera photos (RAW, JPG) and movie captures to the archive. It's going at a smooth rate of 3 MB/s, on average:

I'm using FastGlacier, which seems pretty awesome, and is only $40. They have a slightly crippled free version too that can only do two parallel uploads.

Tuesday, May 21, 2013

Nice+Monaco Trip, Day 0

I'm on a ten day trip to the French Riviera for sightseeing and to see the F1 race in Monaco. I've been documenting the trip with pictures and keeping track of my thoughts on a day by day basis.

Departure from JFK

Typically lousy JFK departure experience. We arrived at Terminal 7, which had our Iberia/British Airways flight. As usual, there was a long line through security. The security check -- taking off your shoes, all metal, separating out electronics - is easily the most stressful and aggravating part of travel for me. It's all just security theater and a waste of eight billion dollars of taxpayer money. We waited around our departure gate for a few hours but got onto our flight on time.

The Iberia flight was the best flight that I've ever been on. American carriers are all about the bottom line; everything costs money and they try to upsell at every possible opportunity. Emergency exit seats with more legroom, drinks, upgraded meals, movies, bag checks -- it's all available for a price. The Iberia flight was not like this at all -- we got a great free dinner and then a great breakfast a few hours later.

Dinner: hot stew, garden salad with dressing, bread and butter, and a cheesecake. SO good.
Breakfast: croissant, muffin, candy, plus a sleek box.
They even had lemon slices for the tea. AWESOME.
The flight attendants were also great. They were hyperactive Spanish women who didn't speak a word of english. I learned Spanish for three years in high school and couldn't understand a word of what they were saying because they were so fast (admittedly, I was a bad student). They were really nice though.

Our flight had a layover at the Madrid-Barajas Airport. Our connecting flight was 6 hours after we had arrived, so I had plenty of time to explore the airport. I liked what I saw.

The terminal for our departing flight was of modern construction; it had no ugly low drop ceilings like in JFK. The construction materials were exposed and the environment was built around them, like many other modern designs. At first I thought that the airport was underutilized because it wasn't overcrowded like JFK, but I realized that it was actually correctly sized by design. There were tons of gates and the terminal was organized in a way that traffic flowed without any major clogs.

Metal and Concrete. Source
I really liked the design of the main hall within the terminal. The roof is a tensile structure made of wood and metal supported in compression by concrete struts shaped like top heavy Ys. Each strut is painted a slightly different color, so you can see a cool gradient looking down the hallway. The walls of the main hall are all glass and permit lots of natural light, and there are openings at the top of the membrane to allow in more light that is reflected and diffused by metal panels. When it got dark outside, artificial light shined on the panels instead, avoiding nasty direct fluorescent lighting. Apparently, this design for a terminal is not new; Denver has a similar tensile membrane structure.

Awesome main hall of T4. Source 


The connecting flight to Nice was on a much smaller turboprop. For whatever reason, our flight was filled with teenagers. Like the entire plane. The flight experience wasn't nearly as nice as the flight into Madrid, but it was only two hours long. I really enjoy flying; when the plane takes off, it feels like as if it's taking off because of the collective wills and hopes of everyone onboard. The first sight we saw of the French Riviera was beautiful, and this terrible phone photo does it no justice:

The phone really can't capture how brilliantly blue the water is...
After we got off the plane, our AirBnB host met us. She is an attractive young Russian woman who rents apartments in Monaco that directly face the F1 race track. The going rates for such apartments is 2000-4000 euros for 3 days. We are not filthy rich like that, and so, we're staying in Nice and commuting 45 minutes by train to Monaco every day and sitting in the grandstands. Such is life. The French Riviera apparently has a large community of New Russians with too much money to burn. There is even a Russian supermarket a block away from our apartment.

The apartment that we have is nice - it's a block away from the beach and close to major attractions. The city is small -- 400,000 people in the city proper -- and you can walk along the major diameter in a few hours, easily. After settling in (it was 8PM local time at this point; and probably about 18 hours from when we had departed JFK), my parents and I went to bed early.

Day one tomorrow.

Friday, May 17, 2013

Crown of Chains

I decided to make one last thing in the machine shop before I graduated: a crown. Since I'm no jewelry maker, the crown would have to be made of materials and objects that I am familiar with and know how to manipulate. I wanted it to look imposing, gritty, and have a beauty that reflected the qualities of its individual components. Oh, and I had to be able to source the parts and make it in one day.

The design I came up with is simple and I can't really point to any distinct sources. It consists of motorcycle roller chain, bike chain, and 0.5" diameter steel balls. Everything is joined together by welding.

I got the motorcycle and bike chain for free from two shops that I called up. These shops have to replace chain on a daily basis because it wears out and 'stretches'. This stretched out chain is useless and must be sent for recycling -- or used for silly art projects. I had to clean all the grime and grease off the chains using a mix of soapy water, WD-40, and xylene. I then wanted to strip off the black-oxide on the outside of the chain - it's there to inhibit rust but it takes the shine off of the chain. I got it off using a mix of hydrochloric acid typically used for cleaning concrete. I'm probably going to get cancer from dealing with all these chemicals...

Cleaning off the protective black-oxide coat from the chain. I got
old stretched out chain for free from a motorcycle shop I called up.
After cleaning it was just a matter of a few hours of TIG welding. At this point I'm half decent at it, so I think things went pretty smoothly. It reminds me of taking a leisurely bike ride on a Sunday afternoon.

Getting an arc on polished steel balls is hard though -- there isn't a highly preferred point of arcing on the surface. I wish that I had gotten the tacks to look more consistent, but it looked consistent enough when it all came together.
My workspace.

Here's a closeup of the welding work. That big chunk of aluminum is so that I could keep everything in form while I was tacking. I would tilt the whole jig so that the ball I was welding would not go skittering around while it was molten hot (it did happen a few times though...).
Sphere Packing, anyone?
Here's the final product. I added in the bike chain loops as accents, but they make the thing damn hard to wear because there are now four sharp points of contact with your head. I am going to add a decorative felt lining on the inside, I think.

10 lbs of awesome.

Sunday, October 14, 2012

Robot Omniwheels

For my senior project, I'm working a robot that balances on a ball to move (ie. a ballbot):

A rendering of my robot's drive assembly -- the motors,  gearboxes, wheels, and the ball it balances on are pictured.

The robot is not statically stable -- there is no orientation for the robot to sit on the ball so that it stays balanced without any movement of the wheels on the ball. It is therefore necessary for the 'bot to have some complicated electronics to stay balanced.

It needs an Inertial Measurement Unit (IMU) with some gyroscopes and accelerometers on it to compute its current angle and speed relative to the ground, and it has to move the wheels according to a control system so that the ball remains under the robot (to stay balanced) or slightly off-center so that the robot moves. I'm going to stop talking about the control system because I haven't really put much more thought into it beyond the preceding two paragraphs (OK, I have, but I don't want to look like an idiot on the internet).

What I have put some thought into, though, is the wheels. Those little cylindrical pieces hugging the ball aren't your run of the mill wheels. The robot has 3 wheels, and if two of them rotate in opposite directions while the third is stationary, the robot will move straight in one direction. However, the stationary wheel shouldn't oppose the motion of the 2 other wheels -- it has to have rollers on it so that it can also move laterally to the normal direction of motion. People have come up with omniwheel designs for this exact purpose:

A typical omniwheel design has rollers on the wheel that allow for lateral movement -- when the wheel moves through the axis of rotation, the small roller it is resting on spins.

We're not using run of the mill wheels, and we're not even using run of the mill omniwheels. An important characteristic of omniwheels is the contact surface of the wheel with the surface it is rolling on. The above omniwheels have non-continuous contact surfaces: as the wheel rotates, the wheel loses contact with the ground because of the gaps between the rollers. It turns out that it is very hard to construct a wheel with a continuous contact surface, but such a design was patented in Japan in 2001: 
Japanese Patent Publication # 2001-191704. The magic here is that the contact surface is continuous -- when you look at the wheel from the top down view (as seen here), it looks like a perfect circle.
There have been two teams have have built omniwheels according to this design, a Swiss team and a Japanese team:
The Swiss ReZero robot wheel assembly.
The wheel assembly of the robot designed by Kumagai and Ochiai, 2010

Our wheel assembly is very similar to the one created by both groups:

A Solidworks screencap of our wheel. Three of the rollers are transparent to display  more detail about the inside of the wheel.
We've already started manufacturing the wheels; I'll put up more pictures as the construction progresses.

Thursday, September 20, 2012

I try to get out, but they just pull me back in...

The FSAE team wanted to resurrect the 2012 failcar to show off during Cooper Union's annual Fall Festival as a way to lure in unsuspecting freshmen to join the team. One of the major problems in realizing that dream is that the power distribution on the car utterly sucked and probably doesn't work anymore. So, like any respectable engineer, I decided that I could make a new system from scratch that would be better in every way possible. Since I'm not actively participating this year (wait, I guess this is the first time I mentioned that?), I also decided that this project would be a good segue for the next person in charge of the engine and electrical subsystems.

Here is the product of about three days of work:
The schematic. Ain't it pretty? I taught my protégé the fine art of mitering everything so that it looks professional. Ignore the crossed wires though...
Here's the board. The huge traces are because it's rated for automotive things -- 15A pumps, 15A fans, etc. The big rectangular blocks at the sides are kickass solderable lug terminals. The connector at the bottom is a 35-pin right angle ampseal connector.

Since everything had to get done in less than two weeks (and really in the last three days...), we milled the board in-house on 1/2 oz one-sided copper clad using a 1/32" endmill, which is why the trace clearances are so big on the board. I can't decide if this is a stupid and abusive way to use our expensive CNC mill or only just stupid. There are a couple of designed-in flywires on the board since there was literally no way to put more fat traces on the top layer.

Actual board pictures are forthcoming once I get off my butt and take them. The amount of solder I laid on the traces is amusingly stupendous.

Here are the pictures:
The copper side of the board. Look at those huge blobs of solder! The flywires  are some conduction paths that wouldn't fit on the board. The rectangular bits poking out on the right are the lug slots.

Topside. Looks pretty neat...

Tall, dark, and handsome. Enjoys long walks on the beach and switching motor loads.

Tuesday, September 4, 2012

Equalizer... the stereo one octave edition?

I'm still in GA for a few hours until my flight for NYC leaves, so I spent a few hours reworking my ghetto equalizer. Since more features are always better (amirite guise?), I've changed the design from a mono five band eq to a a stereo eight band eq -- pretty much the threshold at which the thing actually becomes useful instead of a toy.

I changed the design to use the Dangerous Prototypes Sick of Beige PCB profile template because it's more thought out than the mess of arbitrarily placed standoff holes that I had before. The board is also supposedly more "aesthetically pleasing" because the aspect ratio is the Golden Ratio. I personally think that that's a load of garbage, but hey, if anything can make this even more beautiful than I plan on making it, why not? Anyway, the board currently looks like this:

I don't have nearly half the components placed and everything is just in a big blob right now, but... ROUNDED EDGES~!

I'm still sticking to the super awesome OPA1644 opamps, graciously and unknowingly sponsored by TI through their sample program. I'm using the TSSOP packaging this time instead of SOIC. TSSOP is a surface mounted device packaging standard, and SOIC is another. The acronyms are typical irrelevant nonsense, so have this picture instead:

A scaled up picture of SOIC vs TSSOP.
Yeah, this board is basically going to be awesome.

Saturday, September 1, 2012


A few weeks ago, my friend Xo invited me to build a robot at the GT Invention Studio for the robot battle competition at Dragon*Con. Since I have more money than sense, I immediately accepted his offer and bought a roundtrip ticket to Georgia.

My stay in Georgia was only going to be a week, so I knew that I had to come up with a simple and robust design since I wouldn't have any time to do any fancy machining or even time to properly debug and battle test my bot. I whipped together a wedge in solidworks:

...not far from the robot's actual geometry
But more seriously, I did design this wedge:

The design consists of two motors attached to gearboxes that are wrapped in a steel cage, and a top steel sheet that has two bends in it. The wedges in the initial design are symmetric. The design is about 3.1 pounds, which is slightly over the 3 lb weight limit of the 'beetle' category I am going to compete in. The design is strong, stiff, and most importantly, very easy to manufacture on a waterjet, a cool little machine that the guys at GT have.

So, anyway, here's the product of about four days of almost nonstop design and fabrication work:

I christen thee "Critical Space Item." May you rip other robots to shreds and achieve great victory... The dings are some battle testing from facing the bot off against a 12 lb robot...

The top shell is the only change from the original design: instead of a symmetric wedge, the wedge on the front is at about a thirty degree angle relative to horizontal and it also has compound bends on the sides to deflect attacks on the wheels. The back looks like this:

GT seems to have an unhealthy fascination with yellowjackets...
The holes all over the shell are to remove unnecessary weight and make it go fast. The slots in the front of the bot are filled with button head screws to make the robot front-heavy and less jittery when moving. It's only somewhat effective; the bot is a skittery crackhead when it comes to turning and runs at 15+ MPH. The bumpers on the wheels are a lame attempt to deflect rear attacks; they tend to bend in practice.

The competition is tomorrow. I hope my bot doesn't get totally destroyed because I'd like to use it as a Roomba back in the office...