Pet Projects
Noribo
2.009! Senior Product Design Capstone! Woah!
Okay, that should convey the standard excitement levels for 2.009 here at MIT. Big course, big ideas, big teams, and a very unique experience. The premise is to get a team of 20 MIT students together, give them $6500, and see what they can design and engineer over the course of a term. Results are always interesting, and the end is a culminating presentation that had over 1000 people present in MIT’s largest auditorium to review and critique your project. Beavitvl.
The theme of the year was “food”, very open and with endless possibilities. Our team went with building a novel way to deliver food in restaurants, in this case a small swarm of robotic plates that would ferry food from the kitchen to you. They had several interactive features, most importantly a dance they would do when a plate was removed from them. The idea actually started as a robotic coaster for delivering beer in bars, seen as a way to alleviate the pain of waiting for a bartender in a packed bar. With time the idea muted to all-purpose food ferrying, so it goes.
Our robot in an exploded view.
The bot was a fun design project. I was in charge of bringing all the disparate parts together into a final package, and given that a low profile and small form factor was key to success there were many challenges in packaging everything so tightly. Not to mention all the design for manufacture we had to include in our build. Still, at the end of the day I brought a lot of innovations to the table when parts didn’t fit and made sure all the layout worked well. Beyond that, when a problem arose, it was often at the intersection of two or three team’s parts, and I found myself being the liaison between designs more often than not.
Our finalized bot, looking something like a UFO
A depiction of our bots in action
The bottom of our robot
Our bot with a very adorable sushi plate on top
Our bots went through quite a few design revisions, mind you. There were basically three stages. During the mock-up, we threw together a bot in an inordinately short amount of time, having a radio-controlled bot with the basic form factor done in some 5 hours one Saturday. Surely a testament to the rapid prototyping skills of a modern caffeine-injected MIT student with a nice machine shop at hand.
The first bot had an acrylic shell that we laser cut and assembled with Charles Guan’s infamous “T-Nuts”. Powered by an Arduino and a random smattering of battle bots components, it served bravely, but was dismantled to make the second iteration. This guy featured a 3dp chassis with an acrylic top plate that was etched to produce interesting different designs. It also featured LEDs for different underglow colors, which the judges loved. Guidance was provided via wall-following with IR sensors, the idea being that it could follow a small lip placed around a bar.
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A really fun project, a lot of good memories, and a experience I wouldn’t pass up. Thanks Prof. Wallace!
-Cd
ExoSense
One of the projects I’m working on currently is to develop a new set of senses for people. The field’s loosely called “exosenses”, and right now we’re flying the idea of developing new senses using tactile feedback and a smartphone, immersing the mass of digital and networked information available through feedback. With time this feedback becomes integrated, the stimulus becoming a new independent sense as real as any other.
For now this is taking the form of an Android phone talking over 3G with Google Maps and interfacing to the body with a set of actuated solenoids on a belt. Drop a waypoint or tag a reference, and Android constantly gives you feedback on the heading of the marker. All without ever looking at a map or thinking, just feeling through your new sense.
The Arduino, compass, and demux for actuating the belt
3-Axis CNC Mill
The Epic 2.72 Mill
2.72 holds a certain special place in the heart of anyone who’s ever taken the course. Stockholm Syndrome, some would call it, but I prefer “Survivor’s Glory”. The course centers around the design and build of a precision desktop lathe using parts and a budget provided for in the class. Marty walks you through a lot of design steps and labs, and every two to three weeks your team meets with him personally in design reviews.
These events are always exciting. I remember that for the first design review we got an email two days before saying “none of you have been in contact with me about what exactly I want to see in the first design review. Interesting, given that I’m your boss here and I expect certain elements to be complete. Further, I refuse to accept incomplete presentations, and will require you to push back a day. Each day you push back removes 75 points from the 100 possible design review points, and do note that negative scores are possible.”
No one had completed what was necessary to present the first day.
We came in on the second day and showed off our work, which Marty was quite pleased with, but regardless we walked out with 15/100. We all hoped these were “who’s line is it anyways” points.
Our team significantly differed from the standard 2.72 team in that instead of designing a lathe as was typical for the course we opted for the alternative design goal of making a 3-Axis Milling Machine. The specifications weren’t clear, and we were forced to execute a very open design loop in order to decide on what our final capabilities could be, and from there work back to the actual machine design. The experience was quite worthwhile, and more to follow on our actual design decisions, but for now these images will begin to convey the work we put into building this monster of a design project. And remember, we not only made design decisions and modeled each component, but also machined and assembled everything here.
The 18V Dewalt drill motor and belt drive assembly
A good shot of the mill bit (3/8" 2 flute) and work table, with a "sacrificial" piece of Al bar stock on board
A sample light cut (long traverse) and a full width, high speed, high depth-of-cut (jagged death-looking traverse)
The mounts for the two tables, with flexures visible
Our special flexure for the lead screw thrust nut. Works incredibly well, allows around 1/8" flex in any direction, but holds several 100lbs axially
Our vertical bed translation axis, using a 6in main support column and 5/8in drill rod for translation.
Kinematic Coupling joining our spindle to the support neck. Theoretically allows us to change to other head attachments while maintaining endpoint accuracy
1972 Yamaha RD350
This bike was the love of my 2010 summer while staying at MIT doing undergraduate research. I picked her up for a dime when it looked like a mix between a vintage tracker and a kid’s dirtbike. Terrible shape, really, but a diamond in the rough if you know how to hold a wrench right.
I spent quite a few nights laboring long and hard to bring out what I wanted to see in the bike. She’s almost there now, and the work I’ve put in has completely transformed the look.
To date I’ve:
- Replaced the rear shocks with some beautiful Marzocchi Strada Ducati adjustable shocks
- Found a new side cover and oil tank with the retro R5 chrome accent
- Picked up a set of cafe handlebars
- Bought a new cafe seat
- Installed reasonable (not-70′s-enormous) turn signals and brake light
- Completely tore down and rebuilt both carbs
- Added a new four piston Tokico front brake caliper with custom mounting bracket
Have to say I’m pretty proud. Next up? New seat, Aluminum this time, and maybe some head work to boost performance a bit.
Full on of the bike's left side.
Nice four piston Tokico brake caliper and custom mounting plate
The new Strada shocks. So nice
TV Oscilloscope
A quick update on a random and fun evening. A hall mate and a few friends from around Senior Haus showed up to tinker around with a TV we were disassembling. One cool thing found online to do with a spare CRT is to drive the deflection coils with audio frequencies and make a cool visualizer out of the thing. We did just that and had a grand old time messing around with Audacity and some music files.
The basic premise is pretty straight forward. Take a TV cover off and check out the big tube inside. Be careful not to break the tube (it can implode) or to short the capacitors on the flyback circuit (the one with the transformer and a line running to the back of the tube, where the electron gun lives) or touch the anode running into the tube near the screen, with the big high voltage line and the rubber coating and what not. Now that you’re looking at the tube, find the terminals for the deflecting coils. They’ll look like this:
Close up on the deflection coil terminals (Large posts with green wires attached).
These coils control the horizontal vertical deflection by generating a magnetic field and literally pushing the focused beam around. Now that you have these terminals identified and some leads so you can do something fun with them, grab yourself an amplifier and run the leads into the output posts. Join some speakers into the same posts, and find an input source for your computer. Here we’re using a spare low quality amp and small computer speakers with a USB DAC hooked up via RCA, but an 1/8″ to RCA wire would work just fine as well.
With this, you’re ready to drive the channels with your laptop and some nice free software like Audacity to make some really spectacular things happen. By driving the left and right channels, you can independently drive the horizontal and vertical deflections of the beam. So you can do something simple like have the left and right channels be driven by a track, and you’ll get circles for in phase balanced music, and fun shapes otherwise. Even more interesting is to drive the horizontal axis with a sawtooth wave and the vertical with a signal, say a square wave, and generate an oscilloscope image of what you’re dealing with. Neat! You also still get music output from the speakers so the whole thing makes for a cool system visualizer that is live and a bit different from what you’ll normally see. When you don’t drive it, the beam sits centered on the screen at fairly high intensity, meaning the phosphor will be burned out fairly quickly. In fact, the TV screen isn’t designed for this heavy of a load, so you’ll burn the phosphor fairly fast this way. But CRTs are old and cheap, so no big loss.
Below you’ll see a picture of my hall mates watching the image kick on, the initial stand still beam, and a tracking sine wave. Try it out!
Electron Beam sitting still on screen center.
Electron beam etching a sine wave across the TV Tube.
Take care and enjoy kids!