[WIP] [DIY] LEEP- Optics HMD

[Rec0iL]

Hi MTBS forum!
So this will be my first post and my first thread here.
Thanks to a lot of information i build my first prototype within 2 hours with my smartphone from a cardbox... i managed to get Interaction with my PC with splashtop and FreePIE and VireoSMT
I also tried the combination of Tridef 3D and a gyro mouse but having 3 dof was far cooler and the wrapped screen was better than the plain SBS of Tridef.
Here the embarrassing prototype xD:

IMG_20140710_160735.jpg

(mobile phone goes in the back, lenses were from cheap binoculars)
So i was pretty amazed by the 3D feeling and getting immersed and i started to get thinking about my first real build...

So for the head mount i found my old ski googles which are pretty comfy. Maybe ill attach another headstrap over the head not just around..
For the housing i will cut from polystyrene packaging.

For head-tracking ill use a Polulu MinIMU-9 v3 http://www.pololu.com/product/2468 and conversion to PC will be done by my Raspberry Pi, i'll make the output compatible with the FreeIMU support of FreePIE (http://andersmalmgren.github.io/FreePIE/) (if you need the vireoSMT plugin you can compile it yourself or i could upload it somewhere)
I will publish all code i will use or write for anyone intrested in rebuiding this one.

For lenses i will use an LEEP system.. I was searching pretty long untill i found the principe of leep Optics and a sketch so i redesigned it in OpticalRayTraycer 3.3 http://arachnoid.com/OpticalRayTracer/

LEEP optics.png

1 square is 5x5mm (right eye)
after my first mesurements this should give me a FOV of about 120-130° horizontal

Right now my problems are where i could get such lenses and not be poor afterwards..
and i need a monitor with a driverboard and the highest resolution possible, i could even find a 1980x1050 7" screen but 395 € were too expensive im looking more for something about 100€ max
right now im sticking to this one http://www.amazon.com/JBtek-Resolution- ... h+1280x800
Seems ok and inexpensive for this resolution...
and last but not least i will use a HDMI with a twistable jack:


I'm thinking about adding X,Y,Z tracking but i'm not sure if I want it...
Any suggestions and ideas welcome

PS: I will start building aproximatley in about 2 weeks (wating for salary xD)

[Suncho]

Nice work. There aren't many sets of LEEP lenses floating around these days. The original molds still exist, so we could conceivably have more made, but I'm not sure how much that would cost. Also, they're pretty heavy. I'm not an optics expert, but I wonder if you could get similar optical properties from lighter/cheaper fresnel lenses.

[Rec0iL]

Fresnel lenses are a thing i also thought about... But i'm not sure exactly what to choose... I never had some to play around...
And yes you are right.. i was searching for lenses (for the LEEP optics) at aproximatly these dimensions and curvature but couldn't find any or i found em and they would cost just one lense like 300$ ridiculous
and as i need 3 per eye this seems out of affordable price range... and out of glass so they would be very heavy...
Maybe someone with the access to lens making can use the data. I can post exact curvature etc to make them out of good quality plastic...
Of course I'm not exactly sure since the only source i found was this http://fp.optics.arizona.edu/opti588/re ... a_2005.pdf see page 8
and i tried to replicate it as exact as possible..
Too bad i can't simulate fresnel lenses in OpticalRayTraycer
But if anyone has expierience what would be a good fresnel lense for a 7" screen let me know... (better said 2 lenses for one 7" screen xD )
Open to any ideas..

[Suncho]

Hmm. The LEEP lenses are actually injection-molded acrylic, not glass. But they're heavy because they're so big.

I don't have any other advice. Good luck!

[Rec0iL]

Small status update:
So my Pololu MinIMU-9 v3 came today and I'm trying to get the readings on my pi then send them to my PC.
Another thing i will try in the next couple days.. I'll try to use an arduino. A friend of mine will borrow it to me. If it's good i'll tell you...

EDIT (23.08.2014 2:30 GMT+2) :
Getting raw values, some issues with the magnetrometer calibration hopefully i'll fix em tomorrow in the evening...
https://github.com/DavidEGrayson/minimu9-ahrs/wiki is what i used so far.. tomorrow i'll try out
https://github.com/richards-tech/RTIMULib both seem promising...

EDIT (27.08.2014 5:32 GMT+2):
So im getting the orientation displayed and fusioned and filtered by my pi with both librarys..
So next steps are i think writing a plugin for FreePIE to get the RTIMULib readings using SyntroPiNav https://github.com/richards-tech/SyntroPiApps wich creates a datastream through the network
On the recieving end is a ubuntu pc needed so thats a no go at the moment... ill see if i can grab the stream with some coding of my own if i analyze the source code enough..
Or maybe i can build a wrapper somehow..
Another thing i've been thinking about is using 2 monitors like in another thread here on the forums http://www.mtbs3d.com/phpBB/viewtopic.php?f=26&t=18335
I would simply use http://www.amazon.de/Liqoo%C2%AE-Splitt ... I+Splitter an hdmi splitter to get both screens running..
And for that purpose fresnel seems like the best option...
Small Youtube Video from the IMU
https://www.youtube.com/watch?v=9MOy696XAKk

8.9.2014:
So i got the IMU hooked up to an Arduino Uno... And it already gives out the correct output... like the Razor IMU...
But FreePIE gives some Errorous readings with +E89..... bla will post images and code later/tomorrow..

[Rec0iL]

Well here is my problem... Im pretty much stuck here...
This is the Arduino output

Arduino Output.PNG

And this the FreePIE output

FreePIE Output.PNG

Edit: COM port and baud rate are set correctly

as a comparison this is what the Razor IMU output looks like:


I think i found out the issue... and its the baud rate... as the razor IMU expects 57600 baud and mine is expecting 115200
now I'm thinking how to start as there are 3 possibilities:
1. Rewrite RazorIMU_AHRS to fit PoluluIMU
2. Rewrite PoluluIMU_AHRS to fit communication with FreePIE
3. Rewrite the part of FreePIE

im gonna look for sources... open to any ideas...