[Part 1] Project Initiation

"Building a UPC (or aka DIY Segway) is certainly not an easy matter. To build one, one has to be able to set up and run a microcontroller with a digital feedback mechanism. Depending on how stable and smooth you want your machine to run at, some knowledge in noise filtering algorithms is also required. But most of all, you must have an access to a machine shop or at least an access to a milling machine, a saw and a lathe. Once you have all these, you are pretty much good to go."

There are a few good websites on the topics of DIY Segway and each of them was very helpful. Some of them concentrate on the details which some other websites are rather taking for granted. For example, the famous website (well famous among the DIY Segwayers out there) by Trevor Blackwell gives us a nice list of parts and some follow-up detailed pictures of his segway, but he doesn't really go about telling the details regarding how the signal from sensors gets processed and incorporated into the balancing feedback. A blog called "Starino" talks about how this should be done in plain English but it doesn't really say about the Segway hardware part anyway. So, all in all, visiting various websites and fitting all the pieces of puzzles together is quite important before you commit yourself into this project.

Trevor Blackwell said building one is not that hard. This certainly seems true once you realize all the pre-written codes on the balancing bots out there. All you have to do is to change some constants in the codes to fit that into your specifications. Unfortunately, that's only true if you want to build one that behaves like a Segway and nothing more. Once you jump into polishing your feedback mechanisms and trying out various filters to control the measurement noise and all that stuffs, that's when everything becomes ugly and time consuming.

My project is, of course, building a Segway from scratch. However, I took a little further into incorporating lots of safety measures as well as some fancy user-oriented features (such as RFID ignitions). Also, aesthetics was a quite important factor to me. Therefore all the components that I ordered had to meet certain criteria that I've set for myself.

Specking out the components is relatively an easy task especially if you plan to build one from scratch. For example, say I have a set of bearings which go with the main axle. Since everything is from scratch, I just had to machine my chassis to properly house the bearings I've already got and not the other way around. I guess, what I want to say here is, when you are specking out all the parts, you don't have to care about minor details since you have already given yourself an ability to fit your design into whatever components you have by building from a scratch.

The following list shows a quick break-down of all the components I bought. The list contains 95% of the parts and, in principle, anyone can build a Segway using only the components in the list. 

12'' Wheels (Northern-Tools)
$33.97
Propeller Board, Accelerometer, Gyroscope, ... (Parallax)
$64.90
LCD Module (eBay)
$11.99
Gear Boxes (BaneBots)
$236.35
8'' Wheels, 1/8'' Keys, 0.5'' Hubs, CIM Motors (AndyMark)
$128.68
12V Battery Charge Indicator LED (eBay)
$16.89
1"x2"x0.125"x48" and 0.75"x1.5"x0.125"x48" Rectangular Al Tubes 
0.375"x12"x24" Al Sheet, Nom 0.5" 24" Al Pipe (OnlineMetals)
$123.26
Schwinn Rubber Grips (WalMart)
$8.44
6 10-AA-Battery Holders (BatteryPrice)
$35.35
Tenergy 12V Charger, 60 1.2V 2500mA AAs (All-Battery)
$97.88
2 OSMCs, 2 12VDC Fans (RobotPower)
$364.00
Al Casings, Ribbon Wire 50ft (AlliedElectronics)
$67.00
Various things from McMasterCarr
$154.19
LEDs, LED Drive (Luxeon Star)
$53.19
Potentiometers, Knobs, 10-pin Latch Connectors (Futurlec)
$60.67
PVC Board, Terminal Blocks, Wire Hooker (RadioShack)
$11.09

I didn't specify which gear box model I bought as well as the things I bought from McMasterCarr and Parallax. If you want to know about the details, you can send me an email. From McMasterCarr, I bought 2 bearing blocks, two fuses (30VDC, 40A) and two fuse blocks, two shaft collars, rubber metal edge protector,  4-disc tumbler, and an anti-slip tape. I'm using some 4 2-56 screws to hold the display, 4-40 stainless steel and nylon screws to fix electronics to the main chassis, 2 1/4 screws for structural members like a beam that houses battery packs, 4 1/2 screws for more important structure members (bearing blocks), and few more screws and custom shear pins to complete the assembly. These are not shown in the list. If one has to include them, I expect them to cost around $50~75 (which is the best case scenario where there is no minimum quantity order or expensive shipping service).

Some of the parts are going to be shipped at a significantly later time scale (such as the order with FuturLec and BaneBots. The usual lead time on their shipping service is 15-20 days). Things I bought from eBay may come late but at the same time the LCD module and and battery indicators are not critical components of the design, so it is okay. Once I have all the parts, I should be good to go with hardware manufacturing and I will keep writing a post on my progress as I do that.

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