An idea for the automatic pano head - page 2 - Creative Uses of CHDK - CHDK Forum
« previous next »
Pages: 1 [2] 3   Go Down

An idea for the automatic pano head

  • 27 Replies
  • 17169 Views
*

Offline drewster

  • **
  • 56
Re: An idea for the automatic pano head
« Reply #10 on: 16 / November / 2008, 14:31:16 »
Advertisements
Ingenious, look forward seeing the photographic results,  if you don't mind posting.  Can you let us know the details on how to read the usb (open or close switch) thanks
Logged
G9, Ixus75
*

Offline dsvilko

  • *
  • 34
Re: An idea for the automatic pano head
« Reply #11 on: 17 / November / 2008, 03:12:48 »
Thanks!
Reading the usb voltage (on/off) should be possible with the get_usb_power script function though I haven't tested it yet.
Logged
*

Offline dsvilko

  • *
  • 34
Re: An idea for the automatic pano head
« Reply #12 on: 17 / November / 2008, 10:29:38 »
Ok, here is how the feedback is supposed to work. First, the hardware:

A rotating push-switch (the same as the 'yellow' one) is mounted above a static disk that has one hole. The disk keeps the switch closed (USB voltage high) as long as the switch is not above the hole.
The get_usb_power function always returns a 0 except when the voltage went from high to low when it returns a length of time that the switch was held closed.
So, let's say that we start at some random position. What the script needs to do is to turn the LED on (start the rotation) and keep it on as long as we do not recieve the second non-zero value from the get_usb_power function. The first will be the time it took to the hole the first time and the second value will be the full revolution time T. From the current zoom level (get_zoom) we can calculate the field of view. The slide duration is then something like T*(FoV+1)/360.
Logged
*

Offline dsvilko

  • *
  • 34
Re: An idea for the automatic pano head
« Reply #13 on: 05 / December / 2008, 08:56:32 »
Ok, the pano head (motorized in 1D) is more or less done. I still have a few problems with the get_usb_power() function not always returning what it's supposed to but the LUA script that controls it is also close to finished.

Here is the hardware. I really have to get a stronger tripod - the camera and pano head together weight more than 1kg :)


And here is a test indoor panorama:


Bear in mind that I have spent less than $5 making this pano head, all thanks to CHDK! :)
Logged
*

Offline drewster

  • **
  • 56
Re: An idea for the automatic pano head
« Reply #14 on: 06 / December / 2008, 06:57:53 »
Hi,  nice woodwork.  Looks like a great candidate for an instructable.  Look forward to some outdoor pans when you get the script working
Logged
G9, Ixus75
*

Offline chester320

  • *
  • 3
Re: An idea for the automatic pano head
« Reply #15 on: 15 / December / 2008, 19:50:29 »
I am in the midst of this exact same project. In my case I tore apart a VHS tape rewinder to get the motor and rotating base. Otherwise it's almost exactly the same. Great minds think alike?

To get a light-controlled relay, I tried a circuit with a phototransistor and a 2N2222 transistor to drive a relay, but my electronics were not up to the task. I found a kit for $10 at Fry's Electronics that does precisely this, using a photoresistor, two transistors, and a relay, plus some resistors and a diode to block the relay's kickback current. I'm a digital guy: I never know where the resistors go or what values to choose, so I'm happy to pay $10 for the finished kit.

The printed-circuit board that the kit comes with is too bulky, so I got a breadboard for $1.00 at an electronics surplus store and I've diagrammed a layout for the components. This also lets me put in pins to plug in all the pieces cleanly:

   9V power in
   Photosensor that goes to the camera's AF beam and controls the relay
   Motor power/ground output (controlled by the relay)
   Microswitch that senses the rotation position
   USB input to the camera (so it knows if the microswitch is open or closed)

I also have an on/off power switch, all on a PCB about the size of a 9V battery.

Tonight I solder.

Mechanically, the VHS rewinder has a motor and a belt-driven wheel. The driven wheel rests on a spindle fixed to the bottom of the plastic casing. Turn this upside-down, and the bottom of the casing is now my rotating platform. I molded a tripod mount out of PVC plumbing, a lock nut, and hot glue.

I can only rotate horizontally - I'm not controlling the camera's tilt. I figure I can do that myself: shoot a round, tilt the camera, shoot another round. That won't give a full 180 degrees vertical, it takes just over three rounds for that. But it's a great start.

It's a little noisy: there is a loud "click" of the microswitch falling into the gaps between spokes on the wheel. Next time I'll use a photointerrupter: I want this to be usable in a quiet area like a manor house or a museum (those that allow cameras) without getting chased out by a docent.

For the software, I'm still hacking at LUM to sense the "remote" input state and control the AF beam output. When it works I might write it up on a web page or post it to the "finished scripts" area.

Logged
*

Offline dsvilko

  • *
  • 34
Re: An idea for the automatic pano head
« Reply #16 on: 16 / December / 2008, 02:22:15 »
Welcome to the club!  :)
Could you post a few pictures? I am extremely interested!
I was a bit busy lately and still haven't discovered why does my camera does not detect the USB power on every microswitch press. It's really driving me crazy.
I can send you my lua script if you like.

Good luck with your project and pictures, pictures, pictures! :)
 
Logged
*

Offline Sasha

  • *
  • 8
Re: An idea for the automatic pano head
« Reply #17 on: 16 / December / 2008, 15:43:14 »
A fine way presenting multi megapixel (or even gigapixel) panoramas over the internet is this browser plugin:
Microsoft Research HD View
Another 'panobot': Fehlermeldung - Panorama Community

In conjunction with the Powershot SX 1S with it's 560mm focal length, such a toy would be absolutely fabulous!
Logged
*

databoy

Re: An idea for the automatic pano head
« Reply #18 on: 20 / December / 2008, 01:25:22 »
Guide for building a CHDK Panorama Rig.

CHDK has opened up unlimited possibilities for CHDK compatible cameras. It is remarkable that a group of guys have managed to reverse engineer closed hardware code and enhance the capabilities of point and shoot cameras to rival the capabilities of professional cameras. Guys; keep up the good work.

There are a number of home made panorama rig designs circulating on the net. Most of them have inherited design flaws to be useful or practical for a CHDK based panorama rig.

Building a panorama rig looks simple but in reality it is complex. The hardware requires precision movement to be successful. It is not as easy as gutting a floppy drive for the stepper motor, a hard drive for the bearing assembly movement and gluing a camera mount on the centre. A floppy drive stepper motor has relatively no torque; it is designed to drive a plastic read/write head on guide rails not rotate a heavy camera. Professional panorama rigs use geared stepper motors. They are precision equipment and expensive to buy. By the time you have purchased all the parts to build the rig, it is cheaper to buy a professional ready built rig.

One alternative is to use servo motors. The KAP guys have years of experience in that field. They have perfected the electronics and hardware. It is cheaper to buy a ready made rig and electronics than buy the parts and construct it yourself. There is one disadvantage to using a KAP panorama rig on a tripod mount. A KAP pan/tilt rig is designed to be mounted on a kite with the rigging evenly balanced. It is designed to be flown, then dismantled and cleaned before the next flight.

A redesign of the KAP pan/tilt rig is required for the rig to be suitable for tripod panorama photography. KAP pan gearing is on top of the support rig, using the kite to suspend the rig. A tripod based rig needs to be compact, portable, containing dust free gearing. Most important the gears need to be on the bottom with the geared shaft supported in two places. The modifications can be done but you may have to build a custom tripod or modify and balance the rig weight on an expensive commercial tripod. If you choose to use a KAP rig design, it is best to join a KAP forum and ask for expert advice. The chances are that the components used may be universal and the support bearings available as a kit.

Build your own rig.

With a panorama rig you are only interested in the horizontal aspect. The vertical can be manually adjusted. You do not need a remote control; therefore a geared motor instead of a servo can be used. The cheapest motor on the market is the geared motor assembly salvaged from a cordless drill. The down side is the rotation is too fast for panorama photography. Pulse width modulation chips are readily available. The PWM chip performance surpasses a software programmed microcontroller design. The PWM chip timing is enough to pulse drive the motor, but not long enough to overheat the motor from continuous pulsed use. 

For example an S3IS camera using a SanDisk Ultra II card will only shoot photos at 5 second intervals. Any faster, the camera will not respond. A simple way to pan the rig is to use a CHDK USB shutter release cable to shoot; one second later activate a one shot to turn on a 555 timer. The 555 timer switches on the PWM to the motor. You need to allow a two second stabilising time, and then repeat the process. The electronics design aspect is simple; hardware timers chained together without any feedback from the camera.

Dismantling a cordless drill.

Most of the cordless drills are simply held together. Once you unscrew the casing, the motor and battery assembly drops out. Cordless drill chucks are held into place with a screw located inside the chuck. The screw is right hand thread. Open the chuck fully and with a screwdriver turn the screw clockwise to remove it. The chuck is conventional left hand thread. Place the chuck side on a block of wood and hit it with a hammer. You will end up damaging the chuck before you can unscrew it. You will need to buy two nuts and washers for the bracket mount. Keep the screw; you may need it as a locking screw. What you use for a housing and camera mount is dependent on readily available materials. The KAP guys have plenty of photos of camera mounting brackets.

If you have access to the right tools and a drill press, a stepper motor can be used instead of the existing motor. You will need to dismantle the gear box assembly, remove the hammer components and re-grease the gear box. A geared stepper motor will give you a precision stepping rate. You only need a very simple one step function. There are plenty of simple stepper circuits circulating on the net. Use readily available components.

The panorama step/travel distance depends on too many variables to publish a one size fits all circuit. It is purely trial and error. Keep the electronics design as simple as possible. If you are using 555 timer circuits, be aware that the first pulse on power up on common variety 555 is inaccurate. That is an inherited design fault in the 555 chip design. Power up the chip let it stabilise, do not use the power rail to switch the timer on and off.

Barrel distortion photos look horrible. It is best to have many photos with a large overlap than a few photos with a small overlap. Use the CHDK USB cable to trigger the shutter and single step/pulse to your next location. Once you have worked out your step/travel for a given focal distance, you can automate your pan procedure.

Currently I am building two panorama rigs. One using a geared motor with one revolution in 10 seconds; the other a heavy duty geared stepper motor. Once I have perfected the rigs, I will post an updated guide and general purpose reference circuits.

Keep It Simple Stupid.

CHDK enhancements and scripting has made most of the high tech pan designs circulating on the net obsolete.

Google; there are enough simple general purpose circuits that use 555 timers, stepper and PWM circuits. Use circuits with cheap readily available components in your locality; because if your rig breaks down, you do not want to wait months for an exotic component - or - find out that the original hardware designer/developer has disappeared.
Logged
*

Offline chester320

  • *
  • 3
Re: An idea for the automatic pano head
« Reply #19 on: 20 / December / 2008, 23:35:07 »
Disaster!

I have an SD800, and it turns out this camera does not support the "Remote" button. I have my motor-control circuit all built, but the feedback loop - the rocker switch that tells the camera when to stop the motor - won't work without the remote feature.

I have two alternatives: the easy one is to turn on the motor for a fixed period of time, and hope for the best.

The hard one is to rewire the circuit to make the motor control an "OR" circuit: activate the motor as long as the AF Beam from the camera is lit, OR the rocker switch is open. Figure that after the previous cycle, the AF beam is off and the rocker switch is closed. I turn on the AF beam, and this starts the motor. Then I turn off the AF light, after enough time has passed that the rocker switch has opened. Now the motor runs until the rocker switch closes - with the light off and the switch closed, the motor stops.

This will work, but it is an open-loop control circuit: I light the AF beam, then I have to sleep for a little while and then turn it off - the sleep has to be long enough for the rocker to open, but not so long that it closes again on the next spoke.

Fooey. Just when I thought I had a sweet little robot controller, with closed-loop control logic, I have to rely on finicky timing instead. Of course I can buy one of the cameras that supports the remote release feature, but that's cheating. After all, for $285 I could buy a whole two-axis panorama-shooting robot!

Link to thread discussing the SD800 and its lack of remote: SD800 via PC

Link to Canon's list of cameras that support remote release in the SDK, and don't: Canon Consumer Products

Logged
Pages: 1 [2] 3   Go Up
« previous next »
 

Related Topics