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An idea for the automatic pano head

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Offline dsvilko

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An idea for the automatic pano head
« on: 05 / November / 2008, 14:21:31 »
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It should be possible to build a quite simple 'robotic' 1 (or even 2) axis pano head controlled by the camera itself.
The idea is to use a simple electro motor (with a gearbox reducers) to rotate the camera, a phototransistor switch linked to the focus assist LED and a lua script to turn the LED on and off and take the shots. 
What do you think? Could it work?
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databoy

Re: An idea for the automatic pano head
« Reply #1 on: 05 / November / 2008, 22:59:39 »
Your easiest way is too build a VOX (voice operated relay). Put the microphone near the camera speaker; the VOX output is feed into a PICAXE chip. The PICAXE outputs a pulse to a speed controller which controls your pan motor. Use a script to fire off the camera shots and the process is automated.

Google the net. All the designs are readily available as a kit.
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Offline dsvilko

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Re: An idea for the automatic pano head
« Reply #2 on: 06 / November / 2008, 08:57:32 »
Hmm... I fail to see how a sound activated switch would be a better solution than a light activated one. It's a lot simpler to isolate the sensor from the stray light than from the stray sound (the signal-to-noise ratio should be far greater with the bright camera LEDs than with the low power speaker and microphone). With the LEDs you can have 2D control while it would be quite difficult to get 2D with the sound recognition.
I was thinking something in the line of an extremely simple circuit with a one phototransistor, a 2N2222 transistor and a few resistors switching on a plain ol' electric motor (not stepper) from an old CD/DVD drive + some kind of gear reduction.  Can't get much simpler (and cheaper - $1?) than that.
As the positioning doesn't have to be very precise, I think a stepper motors with all the necessary controllers is a bit of an overkill.
I will try to make a prototype when I have a bit of time. 
« Last Edit: 06 / November / 2008, 10:14:47 by dsvilko »
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Offline fbonomi

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Re: An idea for the automatic pano head
« Reply #3 on: 06 / November / 2008, 09:27:30 »
TIMTOWTDI, and you can work on many different levels.

if you google for "KAP rig" you can have a huge lot of brilliant solutions

LED + Phototransistor + Picaxe + hacked servo would be my favourite approach
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Offline Racenviper

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Re: An idea for the automatic pano head
« Reply #4 on: 08 / November / 2008, 07:52:53 »
Gigapan Systems Online - Homepage Direct Purchase

You can buy the bata verision here. Now figure out the link between the camera and the pano head.
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Offline dsvilko

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Re: An idea for the automatic pano head
« Reply #5 on: 12 / November / 2008, 11:00:33 »
$280 for Gigapan is about $280 more than I was planing to spend :)
I pulled apart an old CD drive and behold, there ware two 5V electro-motors together with the gear reductors.
I have also managed to build a working camera interface from the parts I had at home (4AA battery holder, one 2n2222 transistor, one photoresistor and a 470ohm resistor). The 3 element circuit really couldn't be simpler. The slowest gear currently rotates with 2.8Hz. With the shortest LED pulse the gear rotates about 1/30 revolution or 12 degrees. That's slow enough for up to 100mm tele, even without further reduction! Now I just need to figure out how to mount the camera :)
There are a few advantages in controlling the mount completely from the CHDK as opposed to clicking the shutter from the 'inteligent' mount (as in Gigapan):
- CHDK knows the current focal length and can automatically adapt the 'slide' angle (LED 'on' time)
- it's easier to do EV bracketed panorama
- should be faster in low light as the mount can slide the moment the photo is taken (no need for a 'safety' delay)
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Offline PhyrePhoX

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Re: An idea for the automatic pano head
« Reply #6 on: 12 / November / 2008, 19:33:09 »
RoboterNetz.de :: Thema anzeigen - Vollautomatischer Panoramakopf (Prototyp) (update am 18.10.)
this guy built such a thing btw, and also uses chdk to control the pano head. the guy also posted here on the forum somewhere. maybe he can give you some hints.
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Offline drewster

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Re: An idea for the automatic pano head
« Reply #7 on: 13 / November / 2008, 13:20:18 »
Hi,  I've too been considering building a pano head too,  but intended on making the smart part in the 'head', the only comms between the camera & head,  the shutter.  Didn't know anything else was possible.  Be interested to hear from RoboterNetz to  see what & how he's achieved more.

I'll post progress as & when it happens,  be interested in dsvilko's progress too.  btw I'm planning on a basic Brooxes KAP frame,  servos & picaxe controller.
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Offline dsvilko

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Re: An idea for the automatic pano head
« Reply #8 on: 13 / November / 2008, 15:49:43 »
Well, as the 'electronic' part of my setup works perfectly I am currently working on the mechanics.
I will soon (hopefully) have a working azimuth drive with the resolution of about 1 degree!
The downside of using a simple electro-motor as opposed to a servo is that it's a lot harder to know exactly where you are pointing. Luckily, the exact angle is not so critical as long as the photos overlap. On the other hand, if you don't want to shoot 360deg panorama you need to know the absolute azimuth. To know the absolute azimuth you would have to know the precise rotation speed (probably depends on the current battery voltage) and also be able to 'reset' to one known 'null' angle. Actually I think I have found a way to solve both problems. It is possible (trivial) to mount a simple mechanical switch in such a way that the switch is closed for a half of one revolution (0-180 degrees) and opened for the other half (180-360). We can then use the camera USB port to 'read' the status of this switch. That way we get two known points (where the switch changes status)! Once we have these fixed points we can use them to simply determine the exact rotation speed. This 'calibration' is something the script can do automatically (shouldn't take more then a few seconds) before the each panorama. By using this simple USB feedback it is possible to have a precise absolute positioning even with a unidirectional motor and almost no electronics. The setup is certainly a lot simpler and cheaper than most of the alternatives.
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Offline dsvilko

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Re: An idea for the automatic pano head
« Reply #9 on: 14 / November / 2008, 09:24:48 »
It's alive!  :D
The azimuth drive is working perfectly with the speed of about one revolution in 8 seconds and the smallest slide angle of about 2 degrees! The resolution is even fine enough for a full zoom on my S3 (420mm equiv.)!
And I did it without spending a penny, in less than an hour, only using junk I had laying around the house :D
This is what it looks like (without the camera):

It's just a quick hack to see if everything works. From bottom to the top:
- primary motor from an old floppy drive (can take a really heavy load and rotates with almost no friction)
- a piece of wood fixed to a rotating (upper) part of the floppy motor
- a lid fixed to the static central part of the floppy motor wrapped with a window isolation foam strip (for a better grip)
- an unmodified CD ejection mechanism with another small sprocket glued on top (here, bottom) of the slowest rotating sprocket
- on the left side is a 4AA battery holder and the 'electronics' - one transistor and one resistor
- on the right side is the photoresistor on a long piece of wire for mounting on the AF LED

All the electronics are mounted on the rotating part so no tangled wires!

Here is the pano head in action (sorry for the crappy quality):
YouTube - pano head
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