Jan 17, 2008

Head-Mounted Displays for LEGO vehicles

Having recently gotten over a bad stomach flu, I did what most people would do and grabbed a soldering iron (note to self: do not get the cheap battery-powered version next time!). My goal was to hack a previously obtained "mini spy camera" and combine it with the Spy Video Car Replacement Headset to create a wearable "spy video" hookup for my LEGO vehicles (notably LNE/Packbot, or Serenity for a boat's-eye view). Jake of All Trades did an excellent blog entry about hacking this some time ago, that has resulted in the headset being rather hard to get, but I did manage to order one just before Christmas. The camera is the same as the one Jim posted on a while back (and very similar to this one). The receiver just needed 12V DC and a display to make the system completely portable, so...

Following the directions in the Jake of All Trades blog, I grabbed a battery box, 3.5 mm miniplug, & project enclosure from Radio Shack (the rest of it I had laying about, but still shouldn't set you back more than a couple bucks) and set to work. Trusting the regulator in the headset was good, I risked powering it at 12V DC (risky), so all I needed to do was power both the headset and receiver from the 8 AA batteries (through a switch for ease of use), and wire the video signal from the standard RCA output the receiver provides to the RCA+power miniplug to hook the headset into. I then hooked the battery box to the side of the project enclosure (with 3M Dual Lock), & the whole thing to the back of the receiver (more Dual Lock), and that was it. The result is a nice little B&W head-mounted display that can be stuck in a pocket or clipped to a belt, and allows me to drive around with a "robots eye view" - without needing a TV, or even a laptop & video card. Even for me, this was easy*, and I've not even bothered cracking open the headset unit to switch it to NTSC format (it is set to PAL video by default, & I'd probably get a better image if I performed the hack shown at Jake of All Trades).

Getting the entire "Spy Video Car" (around $100) might actually be a better option for some hackers - I suspect you could gut the RC car and controller for everything you need, already wired together, and just provide the power & case. But since I already had a camera handy, the fact that Wild Planet has just the video headset available ($25 at this time) made it a much cheaper option... not to mention a lot of fun to hack. And that's coming from a guy who is not exactly hacker-friendly (why do you think I like LEGO electronics?).

Now excuse me as I send LNE/Packbot on a search and destroy mission under my bed. I know I has a fresh pair of socks under there somewhere...

--
Brian Davis

*Well, it was "easy" after I figured out I had cross-wired the power and video signals to the headset, and then fought with the stupid soldering iron for 20 minutes trying to undo the work I'd just done... yes, I'm poor at soldering, but not quite as poor as the lousy resoldering job on the miniplug makes it look. And yes, it still seems to work after my mistreatment.

10 comments:

Christopher R. Smith (Littlehorn) said...

Brian, Great job! The package looks perfect...and your solder job isn't all that bad!

I am a little behind you in finishing this project (I have the same setup). Maybe you could send me that stomach bug.

Brian and I happened upon this Hack nearly on the same day fully unaware of eachother's actions.

We both have a bunch of cool ideas that I'm sure will force others to pick up a soldering iron and perform a hack job on something.

These sorts of things are very fun and can provide valuable skills development.

Chris

222Doc said...

I think Brian might have caught the Cyborg bug? Part man part Lego machine now.

Brian Davis said...

...They can also provide valuable flesh burns... well, if you value those things ;).

I look forward to seeing what you come up with, Chris (& others). The biggest question I have is batteries & voltage - the receiver needs 12V DC, but the headset should work fine on less than half that. But two power supplies wouldn't be as small as I'd like, and regulating two voltages off the batteries was more than my off-the-top-of-my-head skill level.

--
Brian Davis

BlueToothKiwi said...

That is cool - and thanks for sharing, Brian.

Seeing you with the head piece actually it reminded me of an old Van Damme film from a dacade ago: 'Universal Soldier'!

Dean Hystad said...

Brian,

You've officially gone from ultra-geek to too-embarrassing-to-be-seen-with. Do you have any daughters?

Dean "worried about your mental health" Hystad

Brian Davis said...

I *do* have daughters, actually... and they wanted to play with it as much as me & my son :). We spent a good part of the afternoon sneaking up on a rather passive cat (he's used to the LEGO chaos, so yet another robot trying to run him down hardly raises a whisker).

--
Brian "now how do I correct the optics for my glasses" Davis

Jonathan Daudelin said...

Wow, that's awesome... now with a NXT controller you'd be completely portable.

-Jonathan

Christopher R. Smith (Littlehorn) said...

Learn from your burns!

BrianBorg, regulating from one battery pack is the way to go and that was part of my plan for the package. My circuit is setting at home. ...waiting.

Chris

Andreya said...
This comment has been removed by a blog administrator.
Andreya said...
This comment has been removed by a blog administrator.
Related Posts Plugin for WordPress, Blogger...