Fixing the cam turret, Baumarkt II

After work I cycled over to the baumarkt ("Home Depot"). I did not buy the fancy EUR50,- table for my saw, but a L-shaped aluminum profile instead. Got some filler, sand paper, aluminum tubing, and "spachtel". It took me 1.5h to find all what I wanted. On the way home missed major downpour by 5min.

Cam pivot with wood struts At home I worked at the cam turret. The modifications I added yesterday nicely straightened out the platform, so everything is perpendicular know.

Serial to Foretrex adapter I finished the day with soldering together a serial adapter for my Foretrex GPS, using hot glue to fabricate a narrow plug.

Trouble with UPS

UPS tried to deliver the DC/DC converter, an AC/DC adatpter, a 3.5" to 2.5" hard disk adapter and an ATX cable to me today. Since I wasn't at home they threatened to deliver the stuff the next day. I phoned, moved the delivery to Friday; they tried again - in vain - on Thursday. Hello?! On Friday I phoned (their office opens at 7:30am) to change the address to my work address. After I gave them the information I'm told "until Monday then". Why Monday? Well, since the address changed... Argh... So, Monday then, while the stuff could be home safely since Wednesday.

The model shop has vanished

Joypad I bought a gamepad controller (pro: two analogue sticks, lots of buttons (12); con: no thrust control), which should allow for some interessting additional functions (and it is much smaller than a joystick).

More buttons Could not get a hold of LMZ, I gleaned from the web site it moved to Emsdetten (20km from Münster). Cycled over, and indeed: the shop is empty. F*ck! Now, how am I supposed to get hold of the stuff I ordered?!

Got Knoppix 3.9, maybe this helps getting the EPIA to boot with the TV card plugged in.

Assembling the cam cradle

Draft cam turret

Camera servos I spent the whole day putting together the web cam mechanics (web cam cradle, servo mounting, rotating cam platform, base plate). Wasn't happy with the result, mainly because the cam platform does not rotate perpendicular to the base plate, though I think I can fix that.


Cam turret, bottom view Tried out the new electric saw I bought, but without some guidance bar I won't use it again - it's impossible to cut a straight line in thin material free handed.


Turret casing (outside)


Turret casing (inside)

Some tests with side effects

Lots of I/O (and more on the board) I used my Shuttle ATX to power up the VIA board. All went well, including booting Knoppix (live-CD Linux - zero installation). With the TV card plugged in Knoppix stalled when starting X, or shortly thereafter. Hm, I hope XP or W2K do better.

While that took me only 1h, it took me 2h to get the Shuttle working again: I believe I had plugged the monitor in the wrong VGA port (it has two). After booting and watching the runnning lights - nothing. Luckily VNC still worked. I tried using the other VGA port, a different monitor, to no avail. The monitor worked when booting Knoppix. After fiddling and cursing I eventually booted the system so that two monitors, one 1024 x 768 and one 1280 x 1024 were visible in the config panel. The correct one (1280 x 1024) was the second. I made this one the primary, deactivated the other , and - zip - the whole thing worked again. Go figure...

Ordering the servo controller and more

I augmented my order at the model shop via email, and ordered the servo controller, compass module, basic stamp and an LCD display at the Elektronikladen ("Elmikro"). Added a couple of items to my order at the model shop: another Rokraft 50mP and a rudder, and I want 2 6V batteries instead of one 12V battery for the motors - it's just easier to get the 6V for the power rudders.

Into the model shop

I had to resend yesterdays order because my email got lost somehow (that's rare...). I went to the LMZ model shop at Aegidimarkt. They don't have much in the shop, but I got some pretty good advice from the owner (like, if the motor I choose is OK, why ships mostly run on 12V motors, whether I need a strong rudder servo (yes) etc.).

I found their prices are quite a bit lower for Robbe items, like EUR11,- for a S3001 servo in the shop and EUR19,90 in the catalog! The lead acid batteries where a bit more expensive, but now they have 12Ah instead of 10Ah while the dimensions remain the same. Bought two Robbe 3001 servos, a 70mm propeller, ordered batteries, controllers, motor and a rudder servo (got talked into a rather big one).

Planned to order the servo controller, a LCD display, a compass module, and a Basic Stamp IIe kit. Could not decide whether to get the display (yes) and the kit (no).

DC/DC conversion

DC/DC converter (narrow strip; built-in) I had some doubts the PW60 DC/DC converter can handle a fully charged lead acid battery - Visual Data said the voltage isn't that high, and a FAQ on the PW I found says that nothing up to doubling the voltage will kill the thing. Got told, too, that 14.4V is the loading voltage for a 12V lead acid battery, not the voltage provided by a fully loaded battery.

Knowing that I ordered

• the PW60/AC-Adapter bundle for a high EUR55,-
• an ATX adapter since I've been told the PW doesn't fit the PD board, and
• a 3.5" to 2.5" HD adapter since the pin out is different between "normal" and "laptop size" hard disks

Downloaded data sheet of HM55B compass module from Parallax - I think I will need that for autonomous navigation. I realized that without the web, doing the research and getting the stuff would have been next to impossible. I think the computer's name will be Loihi (the smallest and newest volcano in Hawai'i; keeping in line with my home naming scheme).

Questions:

• The USB servo controller would be easier to connect to modern computers, plus the USB connection takes care of the power supply. But is the whole combo as good as the serial version (I assume/hope that the USB connection is transparent and will show up as a serial port - as it turned out, it does)?
• How would I interface the compass module with the ITX board (basically I need to provide data in/out plus clock)? Should I use a Basic Stamp for the job (needs 5-12V)? I later did just that.
  
• Is BEC (battery elemination circuit; getting the receiver power from the motor controller) for receivers only, or does it supply the servos, too? It does supply the servos if they are not too hungry.
  

Propulsion

Early draft propulsion I decided or tried to decide on motors and power controllers (which are at EUR70+ pretty expensive!). Should I go for 12V? Slow running low amp motor and big propeller or fast running motor, either with small propeller, or gear and large propeller? The fast running motors allways use more amps.

Then: which power controller is the best? I get the impression, too, that the controllers recommended for the power rudders are oversized (and thus too expensive). How to clarify that? Do I actually need proportional power controllers for the rudders? And: does the servo controller card work with power controllers? I would think so (same plugs), but if not I'm screwed. On the other hand, they just get plugged into the receiver like a servo, so...

Looking for distributors, ordering the computer

I found that the Elektronikladen chain, of which Antratek is a part!, has Parallax hardware, for OK prices. I found out, too, that they can order in all hardware, whether it is in the catalog or not.

VIA EPIA PD 600 mainboard I additionally ordered the EPIA 600 PD mainboard/CPU today at Alternate, after some lengthy research which of the dozen modells fits my needs best, together with some RAM and a laptop size Samsung HD. I realized later I need an adapter to connect the IDE connector on the mainboard (for 3.5" drives) to my laptop 2.5" drive...

Downsizing expectations, and shipping issues

I realized that maybe I'm tempting fate if I want to build a jet drive and bow/aft rudders myself. So I settled in my head for a plain propeller drive and ready made rudders.

I said about Antratek: "Good selection, reasonable prices", until I found out they charge EUR30,- for shipping to Germany :-(. Started looking again.

Ordering from abroad is expensive!

From my recent experience with ordering a Firefox T-shirt from the States I know that customs will slap on toll fees plus VAT on top of that, which roughly doubled the price. So I started looking for a Parallax (the manufacturer of the servo controller) distributor in Europe, and came across Antratek in the Netherlands. Good selection, reasonable prices. But the shipping cost... Stay tuned.

Choosing the brain (computer)

I started looking for a 12V DC power supply for ATX boards. First I tried to build this myself, and I ended up with learning quite a bit about DC/DC converters (buck, flyback etc.), but no concrete solution. I found a nice National Semiconductor chip and ordered a couple of samples (which didn't work out). In the end I wasn't too thrilled building the thing myself because a couple of parts, notably the coils, seemed to be hard to come by.

So I looked at commercial solutions. There seem to be only a few products that everybody sells, ie. the PW 60 and the ITSP (?). The latter is for car use and can deal with spikes, overvoltage, and other car-specific stuff that I don't need.

June 2005 - How it all began

Idea: Inspired by projects such as an autonomous glider thats gets dropped from a weather baloon at 60,000ft I started thinking about a computer-controlled vehicle.

Basic options: Ground/Air/Sea. "Air" is not an option since I have no experience with planes and I figure this option has a high entry barrier. "Ground" is OK, but where in Germany can you really explore (without getting run over by a car)? So "sea" seems to be interesting: Münster has lakes and a canal, and both offer quite a bit of freedom (submarine, anymone?!).

Early draft: A submarine Decision: A boat or a submarine. I choose the boat for starters, since my model experience is zero. Since the computer is the focus, the ship should be reasonably easy to build. I'm thinking of a gravel lighter design which may lack charm but should be easy to build (square shape). Since propellers and rudders can be cought in mud and plants: how about a covered drive (directable jet?), and a bow propeller.

I'm not an electronics guru either. So the inital idea hovers around an ITX board, WLAN, car battery, and remote control via laptop/joystick.

Actuators? Luckily I stumbled across a USB-connected device which controls 16 or even 32 conventional model servos. Perfect! So: brushless engine for main drive, brushless controller, small engine for bow rudder (will this be good enough for easy maneuvering?), and another controller for that. Propellers operating in PVC tubing.

Will the ITX board consume too much power? An ITX board itself consumes about 25W under full load, and needs a power converter. Lead acid batteries are pretty heavy (not so bad with a ship). This does not include WLAN, harddisk and servo box. Option: Lower power embedded PC (problem: OS), or embedded controller like Basic Stamp. Problem in both cases: interfacing devices, nastly programming (C or even Basic).

What I have described so far is using a WLAN-connected computer as a fancy remote control, though transmitting data is very convenient (high bandwidth IP; good for web cam etc.). But I could connect my old GPS and buy an electronic compass to obtain information on position and orientation. This should allow for some autonomous operation (a plane has more tolerance to positioning, less tolerance to orientation; a ground vehicle has rather less tolerance to positioning, but dead reckoning is pretty accurate).

So what could the computer do? "Keep position". "Get me from A to B". "Avoid obstacles". Intelligent operation of servos.

I started to look for low power consumption PCs with Google, and came up with a number of PC104 boards, namely Micro886ULP. I later got a quote beyond $2000; I got the impression they don't want to deal with individuals. The other board is the IPC/NETIPC-5A by SYSLOGIC, but I did not follow up because I decided for an ITX board: full PC, no compromise, and should run for at least 2h on a moderately sized 12V battery (about 20W consumption).

AC.motion - a computer-controlled model ship

First draft of jet drive Currently I'm working at T-Systems and a private project, "AC.motion". It is a computer-controlled ship that can be remotely controlled via a laptop, joystick, and WLAN - that's the plan. The ultimate goal is to give it some intelligence for autonomous operations, such as following a preset track using GPS and an electronic compass.

I'm a software guy, not a model person. I hope my skills are sufficient to get the carpentry done...