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Functioning Voight-Kampff Machine
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Buch
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Location: Copenhagen, Denmark

PostPosted: Thu Feb 16, 2017 10:42 am    Post subject: Reply with quote

joberg wrote:
eye piece (Remington electric grill) 22mm.


Which part is this exactly, Joberg? Want to wright it down in my VK log....
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joberg
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PostPosted: Fri Feb 17, 2017 7:27 am    Post subject: Reply with quote

It was used for the eye piece on the original V.K.



I didn't use it on my V.K.2, I just learn of its usage by watching the vid on Stephen Dane Wink
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Buch
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PostPosted: Fri Feb 17, 2017 11:03 am    Post subject: Reply with quote

Ahhh yes... now I remember!

This, right?


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LearnByMaking
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PostPosted: Fri Feb 17, 2017 9:06 pm    Post subject: Reply with quote

Joberg, thanks for the correction, I'm re-calculating proportions based on that.
Trying to finish a skeletal test rig of the arm movements - taking a bit longer due to having the flu for the past 2 days. Need to check if the servo's I have are good enough or if I need higher torque.
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joberg
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PostPosted: Sat Feb 18, 2017 12:11 pm    Post subject: Reply with quote

Anders: yes, that's the one

Tom, I don't know if you've planed to use light-weight materials for the arm/eye combo? It's a factor for sure, in terms of selecting the right motors.
I know that if you have a stronger motor, you'll add additional weight...You seem to know better in that stuff than me Wink

Anyhoo...I hope that darn flu-like stuff you're fighting will go away sooner, rather than later.
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joberg
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PostPosted: Sun Mar 05, 2017 4:54 pm    Post subject: Reply with quote

Bumperoo for that exciting WIP Wink
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LearnByMaking
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PostPosted: Sun Mar 05, 2017 5:35 pm    Post subject: Reply with quote

Sorry for the long delay in updating progress and status. I've made a bit of progress, despite hitting a lot of roadblocks.

The arm extension, along with the "eye" piece flipping up, is actually working now that I upgraded the servos to ones with metal gears and higher torque. Some issues with the raising of the arm - even using aluminum the arm ends up being to heavy for standard servo's. After testing a bunch of DC motors with reduction gearboxes I thought I would have to order a NEMA 17 stepper motor with a planetary gearbox (they have more than enough torque and holding power for the arm but they are fairly expensive). I still think the NEMA stepper would be ideal but I came across a larger DC motor with a bigger gearbox (was used in an industrial soap dispenser) and it seems like it will just fit into the VK.
Screens have definitely been a real pain but I found one for the main screen that I think is nearly perfect: 5.6inch AT056TN52 V3 50Pin LCD panel (it is a 640x480 display with a 4:3 aspect ratio - just like the 80's only an LCD instead of CRT - can find them from Chinese companies). I'm just waiting for the controller board for it (nice thing is that is can utilize a composite NTSC signal. I have smaller TFT/LCD screens (2.8"diagonal - but I plan to use a fresnal lens in front of each one). These have been a real issue though, after many many hours of attempting to use them I still can't get them to display anything.

Sensors have presented some issues but are progressing rather well. The initial pulse/ox sensor I was unable to get working (mainly due to the small size of the surface mount pads). I found a slightly more current sensor, already mounted in a breakout board - MAXREFDES117#. The advantages of this board are that the component is already mounted and it comes with code libraries to speed development. It is a nice small board but the code libraries from Maxim Integrated do not compile - I contacted the company and they are working on it. Looking for a quicker solution I came across a code library made by Spark Electronics and it actually works (YES!).

Eye tracking software seems to work reasonably well (still messing with the software).

Non-contact Infrared temperature sensor - works but not great at any reasonable distance. So, looking at other ways to address this.

Working to improve the Electrodermal Activity sensor (GSR) - works but trying to amplify and filter the signal.

More to come, with pictures (just trying to figure how to post them so they aren't gigantic).
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LearnByMaking
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PostPosted: Sun Mar 05, 2017 5:44 pm    Post subject: Reply with quote

Oops - I meant Sparkfun Electronics not Spark Electronics.
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joberg
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PostPosted: Mon Mar 06, 2017 7:59 am    Post subject: Reply with quote

Great update...despite the blood, sweat and tears that machine will give you (and I'm not even talking about the headaches ).

I was using a alu tube for the arm (lighter as you well know). The main block for the arm (the one on which the pullies are sitting) is machined aluminium also; hollowed at the bottom as to make sure the tube slides at a 1/4 in that block.

If you look at pictures of the innards, that servo box moving the arm is taking almost the whole length of the machine...for reasons you've discovered. The whole arm + eye combo is fairly heavy Shocked
Let's re-cap for people not familiar with that stuff:

Box at the base of the arm (contains servo for moving tube + gear box attached to the eye.
Alu-block with 2 pullies.
Gear box at the end of the tube
Eye piece.

Now, if you take that whole arm in your hand, it doesn't seem that heavy.
True, but one has to consider the length of the extended arm + gear box + eye piece, making it heavy for a normal gear box.

Looking at the machine, back in the '80s, it's a miracle that they could make it work. Nowadays, the electronics are much more smaller and the possibilities are there to make it work...albeit with some challenges, still present at hand, namely the screens.

You have all my support
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LearnByMaking
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PostPosted: Fri Mar 17, 2017 2:30 pm    Post subject: Reply with quote

Finally - some successful test for the VK arm. I thought this would be the easy part but it definitely wasn't.
Servo motors – primarily the motor to extend the arm, needed more torque and metal gears. I thought I solved this when I got some SG-90 servo's from Tower Pro but it turned out I needed a standard size servo. Before that I encountered one new issue with the servo for arm extension – I incorrectly thought that the servo would rotate more than 180 degrees (for some reason I had it in my head that they rotated closer to 360 degrees - oops). Thankfully I was able to fix this by converting the servo motor into a continuous rotation gear motor ( https://learn.adafruit.com/modifying-servos-for-continuous-rotation/overview ). For the final build I will need to add limit switches to mark the endpoints of the travel of the arm.

Here is a video of my arm extension tests:
https://youtu.be/kaYlae_cq8Y

Next - I'll get the arm raise working! After putting together a test rig for my largest geared motor only to find that it had insufficient torque at lower speeds (controlling with PWM and a L293 H-Bridge). I ended up ordering a NEMA 17 stepper motor with a planetary gearbox (5:1 reduction), the torque ratings look more than sufficient to move the arm.
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joberg
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PostPosted: Sat Mar 18, 2017 9:57 am    Post subject: Reply with quote

Right...so, as you see, that prop keeps on giving (headaches, mostly) Wink
Good stuff Tom; are planing on putting a groove/indentation on the main arm to keep it from rotating while being extended?

What kind of belt are you using for moving the pullies? Eager to see the next update!!
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LearnByMaking
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PostPosted: Tue Mar 21, 2017 12:36 pm    Post subject: Reply with quote

The belt that I'm testing with came out of an old VCR.
I thought I'd have the arm raise working by now but I burned out 2 micro-controllers and 2 stepper motor drivers trying to get it going. Normally stepper motors are no issue for me but now I have to wait for some new stepper drivers to come (a few days).
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joberg
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PostPosted: Tue Mar 21, 2017 4:29 pm    Post subject: Reply with quote

Too bad about the motors Crying or Very sad Is that a grooved belt? You'll need one if not.
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FenGiddel
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PostPosted: Fri Mar 24, 2017 3:53 pm    Post subject: Reply with quote

LearnByMaking: this is an intriguing project. Challenge enough to make a static replica, I'd imagine, but a working model is something else. Best of luck with the contest. Here's hoping you bring home a "blue ribbon".
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