Automated Stack & Stitch System Robots

Have questions about the equipment used for macro- or micro- photography? Post those questions in this forum.

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mawyatt
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Automated Stack & Stitch System Robots

Post by mawyatt »

Ray, Ramón,

Per Rays request to start a new thread on this subject.

The system I'm in the middle of creating is based upon a similar approach to yours Ray. It's built around the Thorlabs 95mm precision rail system I created long ago for horizontal use. Recently I've added a vertical 95mm 600mm long extrusion, which will allow vertical and horizontal use from the same basic setup. After some effort the mechanical aspects are in place and work as expected (extremely stable & rigid).

The focus rails I will probably use are the THK types, though I might use another type rail for X and Y. I'll plan on stacking in the Z axis vertically with the THK. I'm using standard NEMA 17 low voltage ~2A stepper motors (some with 400 steps) with medium length & high holding torque, commonly available.

What I've found doing some research and playing around with many things is that these motors like the better driver controllers which create the micro-stepping by a sine look up table rather than the direct software controlled micro-stepping, but don't be lured into believing that more micro-stepping is better. There is lots of detailed information on stepper motor behavior under micro-step available on line. I've also found that the popular TI DRV8825 driver has some issues with micro-stepping as seen in this well crafted evaluation.

https://hackaday.com/2016/08/29/how-acc ... ng-really/

I had ordered a few of the DVR8825 boards and probably won't be using them, the Allegro A4988 is probably a better choice even though it's only 1/8 micro-step.

For the controlling computer I had initially thought of using the Arduino but decided upon the Raspberry Pi 3B as the base computer for starters and developing the control algorithms & code, many reasons steered me towards the Raspberry including direct WiFi and Bluetooth, HDMI, 4 USB, and micro SD card slot, all built in for $35!!!

Under the Raspberry I've also found that a conventional software loop to step the motor by toggling an I/O pin and count the steps is much too slow for my intended use, and doesn't produce smooth operation due to the OS polling. Using a hardware PWM I/O pin mode (drives the Step input of the A4988) allows a much higher speed and smoother motor operation, but unfortunately doesn't allow any practical way to count the step pulses which is necessary to control the rail position.

So now I'm looking into a micro controller based stepper based driver which does all the "homework" and interfaces with the Raspberry by USB or I2C serial ports. I'm waiting on the Pololu Tic500 boards based upon the MPS MP6500 driver chip I just ordered today.

Pololu is another great story of 3 MIT students forming company from their dorm room in 2000, and doing what they love to do!!

https://www.pololu.com

Eventually I hope to create a good user interface (maybe graphical) for this Stack & Stitch System.

Anyway, that's where I'm at today and I'll report more soon I hope.

BTW one intriguing idea that I've been bouncing around for some time now is the use of very tiny linear rails for the X and Y subject positioning. These would be much smaller that the THK KR15 Ray uses, but more like the tiny stepper rails used in CD drives. This might work because the X & Y positioning doesn't need the resolution or precision of the focus stacking axis. The stitching process should help with any misalignments created during the X & Y positioning as long as enough image overlap is available, and the positioning resolution doesn't need to be micron level, but mm level is probably acceptable for most subjects. Two of these tiny rails could be mounted orthogonal to each other and attached to a small ARCA plate for mounting onto the base system. Too keep the subject side mass low a simple alligator type subject clamp could be employed to hold the small subjects. This should produce a small micro stepper controlled X & Y stage small enough and without significant height to be used on the portable Wemacro Vertical Stand (or similar setup) in both vertical and horizontal modes and still maintain the portability. This must wait until I get the Precision Stack & Stitch system finished or at least far enough along to be useful and productive (read may not have the GUI completed).

Best,
Research is like a treasure hunt, you don't know where to look or what you'll find!
~Mike

Lou Jost
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Post by Lou Jost »

Mike, the Yongnuo flashes have a nice little mini-rail that moves a focusing lens inside the flash head. Might be usable?

mawyatt
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Post by mawyatt »

Research is like a treasure hunt, you don't know where to look or what you'll find!
~Mike

RDolz
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Joined: Mon Aug 28, 2017 9:32 am
Location: Valencia (Spain)

Post by RDolz »

Forgive for the delay, but today it is being difficult for me to sit in front of the computer. It's already late here...

I would like to explain that my design starts from the desire to photograph relatively large objects with an increase that does not exceed 3-4X.

This defined the characteristics of the system, characteristics that surely are far from the usual ones handled for bigger magnifications. I do not intend to demystify anything, just that for my work no major accuracys are necessary.

In any case, developing a system makes it very versatile since in the future you can modify it according to your needs.

Here I make a small outline of the characteristics of my system:

Mechanical from Fuyu, https://www.fuyumotion.com/

The base is like:

https://www.fuyumotion.com/free-shippin ... stage.html

https://www.ebay.com/itm/Linear-Motion- ... 519?_ul=CL

https://www.ebay.com/itm/283006666509

but modified according to my specifications, ... very kind and decisive people (I bought it directly from the factory). It is very robust and I can mount, without problems, quite heavy systems.

NEMA23 motors, 200 steps / rev

X axis two rails 500 mm, 5 mm / rev, direct drive, each shaft an motor.
Y axis one rail 500 mm, 5 mm / rev, direct drive
Z axis one rail 250 mm, 4 mm / rev, drive with reduction 10: 1

Precision axis X = 5/200 = 0.025mm
Accuracy Y axis = 5/200 = 0.025mm
Precision axis Z = 4 / (200 * 10) = 0.002mm

Motor drives, from MICROPAP, a Spanish company that I have known for many years and that has helped me in the development. They are specialized in stepper motor controllers.
 
http://www.micropap.com/index.php/virtu ... 243-detail

Although there are 4 engines I only use 3 drives. One of the drives controls the two motors of the X axis in serial mode. It is not the best. If it were now I would join the two axes with a mechanical system and I would only use one motor ... but it has not given me any problem.

These drives allow microsteps, that is, it could make the motors work at 400 steps / rev ... or even more, but it has not been necessary for me. It is more reliable for an engine to work with the setps for which it was designed.

Own development software with the help of some computer friends.

As I was saying, it does not have a very high precision ...
The positioning in X and Y does not require high precision ... and in the increase that I work, the Z axis gives me more resolution than I need.

Here I show you two images, already old, where I have mounted a coolscan 8000 in telecentric mode. It is also mounted on an Olympus macro system, .. which I sometimes use ....

On the Z axis I build the camera, since this, although it has some disadvantage, allows to mount complex optical sequences perfectly aligned (the force of gravity helps me).

Image

Image

https://easyzoom.com/imageaccess/f09af4 ... d8d877d9c6

https://easyzoom.com/imageaccess/fc7f02 ... 12ef7b086c
Ramón Dolz

ray_parkhurst
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Post by ray_parkhurst »

Mike...I've purchased a couple of the above, and about 10 other small stepper rails like you're talking about. They typically take very little voltage to operate, and overheat very quickly when using a controller like the mjkzz or wemacro. The low voltage/low current means very little torque, and this can't move much beyond themselves and a very light load. They are also surprisingly tiny! The threading is non-standard, so the carriages are not replaceable. So far I have had very little luck making anything work with them. Not trying to discourage, just letting you know the problems you may face. Generally I can get almost anything to work...

ray_parkhurst
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Post by ray_parkhurst »

RDolz wrote:Forgive for the delay, but today it is being difficult for me to sit in front of the computer. It's already late here...

I would like to explain that my design starts from the desire to photograph relatively large objects with an increase that does not exceed 3-4X.

This defined the characteristics of the system, characteristics that surely are far from the usual ones handled for bigger magnifications. I do not intend to demystify anything, just that for my work no major accuracys are necessary.

In any case, developing a system makes it very versatile since in the future you can modify it according to your needs.

Here I make a small outline of the characteristics of my system:

Mechanical from Fuyu, https://www.fuyumotion.com/

The base is like:

https://www.fuyumotion.com/free-shippin ... stage.html

https://www.ebay.com/itm/Linear-Motion- ... 519?_ul=CL

https://www.ebay.com/itm/283006666509

but modified according to my specifications, ... very kind and decisive people (I bought it directly from the factory). It is very robust and I can mount, without problems, quite heavy systems.

NEMA23 motors, 200 steps / rev

X axis two rails 500 mm, 5 mm / rev, direct drive, each shaft an motor.
Y axis one rail 500 mm, 5 mm / rev, direct drive
Z axis one rail 250 mm, 4 mm / rev, drive with reduction 10: 1

Precision axis X = 5/200 = 0.025mm
Accuracy Y axis = 5/200 = 0.025mm
Precision axis Z = 4 / (200 * 10) = 0.002mm

Motor drives, from MICROPAP, a Spanish company that I have known for many years and that has helped me in the development. They are specialized in stepper motor controllers.
 
http://www.micropap.com/index.php/virtu ... 243-detail

Although there are 4 engines I only use 3 drives. One of the drives controls the two motors of the X axis in serial mode. It is not the best. If it were now I would join the two axes with a mechanical system and I would only use one motor ... but it has not given me any problem.

These drives allow microsteps, that is, it could make the motors work at 400 steps / rev ... or even more, but it has not been necessary for me. It is more reliable for an engine to work with the setps for which it was designed.

Own development software with the help of some computer friends.

As I was saying, it does not have a very high precision ...
The positioning in X and Y does not require high precision ... and in the increase that I work, the Z axis gives me more resolution than I need.

Here I show you two images, already old, where I have mounted a coolscan 8000 in telecentric mode. It is also mounted on an Olympus macro system, .. which I sometimes use ....

On the Z axis I build the camera, since this, although it has some disadvantage, allows to mount complex optical sequences perfectly aligned (the force of gravity helps me).
Looks like you went the opposite direction of what Robert is thinking! This system is more like a GigaMacro type of large format XYZ system. Do you plan to shoot large objects with it? It is very impressive.

Always nice to find new sources for hardware. I've been working on automation for a few years now, but have not heard of fuyumotion before.

Brings up a potentially good project for this thread...an FAQ list of the equipment sources for X-Y-Z-R-TipTilt-goniometer-etc types of automated equipment. Maybe we can compile our sources and make it easier for folks in the future?

Andreas Kay
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Post by Andreas Kay »

Mike, did you consider the TMC2100 or TMC2208 stepper motor drivers? The motor runs much more silent with less vibrations. Here is a comparison:
www.youtube.com/watch?v=P3ebhi-vZRY&fea ... be&t=2m35s
https://youtu.be/WtLXszS7_yY?t=1m50s
The camera may move so smoothly that you can just keep shooting in burst or video mode without stopping the motor at each shot.

ray_parkhurst
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Post by ray_parkhurst »

Here are some interesting links that most folks may already have bookmarked but that have proven useful to me.

These THK and Misumi links can help with decoding some of the items seen on eBay.

https://www.thkstore.com/

https://us.misumi-ec.com/vona2/mech/M01 ... 118020000/

Here's a link to Ondrives, who made my first linear rail that got me started in stacking. This is a company many of you probably have not heard of:

https://www.ondrives.com/leadscrew-actuators

Here's a link to Oriental Motors (Vexta) Accessories page, showing their lineup of couplers, mounts, and dampers:

https://files.valinonline.com/userfiles ... sories.pdf

Here's a link to Lin Engineering Stepper Motor Wiring Connections page, which I have found extremely useful:

https://www.linengineering.com/resource ... nnections/

RDolz
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Location: Valencia (Spain)

Post by RDolz »

Hello Ray: Yes, when I designed the system I did it thinking that in his day I could photograph large objects, ... in reality it has not been like that yet.

Now, as it is very robust, it has no stability problems and allows me to work comfortably with any object size. All this is facilitated because I do not work at large magnifications.

The great advantage that I have is that I have a lot of space to work and I have no problem mounting large optical setups. It also makes it easier for me to mount different lighting systems.

Also, as I was saying, verticality offers the advantage of self-alignment and, for my purposes, near zero backlash

As for what you mention about FAQs and compilation, I think it's a good idea ... although I do not know how to organize it.

What I do not think is very useful is that this thread becomes a list of equipment or suppliers of material. I think that an excess of information makes us more dizzy than help.
Ramón Dolz

mawyatt
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Post by mawyatt »

Ramon,

That is a very nice setup you have, first class indeed!!

Thanks so much for the details and suppliers list. I'm sure this will be very valuable for others as well!!

Fuyu Motion seems to have some nice rails for what I'm trying to do, especially the XY setup. Like you I just need the higher resolution in the Z axis if using vertical setup (although I can operate in either V or H modes). I'll need to contact them with regard to some parameters.

With your setup do you notice any backlash or wobble (side to side tilt or motion) of the rails, and what pitch are the screw threads?

Best,
Research is like a treasure hunt, you don't know where to look or what you'll find!
~Mike

mawyatt
Posts: 2497
Joined: Thu Aug 22, 2013 6:54 pm
Location: Clearwater, Florida

Post by mawyatt »

Andreas Kay wrote:Mike, did you consider the TMC2100 or TMC2208 stepper motor drivers? The motor runs much more silent with less vibrations. Here is a comparison:
www.youtube.com/watch?v=P3ebhi-vZRY&fea ... be&t=2m35s
https://youtu.be/WtLXszS7_yY?t=1m50s
The camera may move so smoothly that you can just keep shooting in burst or video mode without stopping the motor at each shot.
Andreas,

That looks like a really good controller, better than the A4988. I've already ordered 3 other controllers from Pololu (Tic500) that incorporate a micro-controller on the small circuit board, this board uses the MP6500 stepper controller driver chip (chip details here). If this doesn't work out I'll take a serious look at these controller/drivers.

https://www.pololu.com/file/0J1447/MP6500_r1.0.pdf

Generally I need to have extremely stable and vibration free exposures (for chip images), so "shooting on the run" would produce too much movement and vibration.

Thanks for the information.

Best,
Research is like a treasure hunt, you don't know where to look or what you'll find!
~Mike

mawyatt
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Joined: Thu Aug 22, 2013 6:54 pm
Location: Clearwater, Florida

Post by mawyatt »

ray_parkhurst wrote:
Mike...I've purchased a couple of the above, and about 10 other small stepper rails like you're talking about. They typically take very little voltage to operate, and overheat very quickly when using a controller like the mjkzz or wemacro. The low voltage/low current means very little torque, and this can't move much beyond themselves and a very light load. They are also surprisingly tiny! The threading is non-standard, so the carriages are not replaceable. So far I have had very little luck making anything work with them. Not trying to discourage, just letting you know the problems you may face. Generally I can get almost anything to work...
Ray,

Thanks, that was hopeful wishing on my part!!

These Fugu components that Ramon has kindly shown certainly look promising for X and Y use though!!

Best,
Research is like a treasure hunt, you don't know where to look or what you'll find!
~Mike

ray_parkhurst
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Post by ray_parkhurst »

mawyatt wrote:
Ray,

Thanks, that was hopeful wishing on my part!!

These Fugu components that Ramon has kindly shown certainly look promising for X and Y use though!!

Best,
Yes, they look very good.

I would suggest one improvement though. The moment with heavy camera and optics is fairly large, and it is countered primarily by the lateral (rotational) stiffness of the X-motor linear rail, with some countering by the X-motor screw. This would not satisfy my desire for extreme stiffness in the system. A simple (and cheap) addition of an idler rail mounted to the platform and running the full length of the X-motor would almost completely eliminate this issue and result in likely >10x stiffness improvement to the Z-motor.

If a rail were added, the limiting factor would then be the bellows focus clamp. I have found with all the Nikon/Canon/Pentax/etc bellows I've tested, no matter how stiff you make the motors, the bellows clamps will always limit system stiffness. I would suggest if you talk with the Fuyu folks, that you ensure the Z-motor is of a dual-carriage type. Examples are the THK KR2001B or KR2602B rails, where the "B" designates an idler carriage. The purpose of the idler is two-fold: first, it reduces the torque on the Z-motor carriages, so they last longer and don't sag. Second, it gives you two mounting points for a more stable platform for the bellows or other mechanism you plan to use for camera and lens mounting.

Indeed what I have done to achieve "ultimate stiffness" while still maintaining bellows operation (rather than arca clamp methods) is to do away with the bellows focus clamp completely, and instead mount the bellows extrusion directly to the Z-motor platform. This eliminates the Z-adjustability of the bellows, reducing Z-range, but I compensated for this by putting two extrusions end-to-end. You must sacrifice 2 bellows for this, but you get a side-benefit of creating a potentially extra-long bellows for long focal lengths at higher mag.

Edited to add: If the dual-carriage rail is not available, you can always add an idler rail instead. This is what I hae done in my system. It has the advantage over a dual-carriage rail in that it can be any length, and thus is preferred if a long platform is used.

One further benefit of the idlers could be to better link the Z-motor to the overall system platform. I see a huge potential improvement in common-mode vibration suppression with this method.

mawyatt
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Post by mawyatt »

Ray,

I'll be using a KR20 or KR26 as the vertical rail for focus stacking, but considering Fugu as a possible XY stage to move the subject. I've asked Fugu about the thread pitch, backlash and rail wobble.

Have some other rails I could use (another surplus KR20, Wemacro or MJKZZ) but they are mounted by cascading ARCA clamp/plates.

Best,
Research is like a treasure hunt, you don't know where to look or what you'll find!
~Mike

ray_parkhurst
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Post by ray_parkhurst »

mawyatt wrote:Ray,

I'll be using a KR20 or KR26 as the vertical rail for focus stacking, but considering Fugu as a possible XY stage to move the subject. I've asked Fugu about the thread pitch, backlash and rail wobble.

Have some other rails I could use (another surplus KR20, Wemacro or MJKZZ) but they are mounted by cascading ARCA clamp/plates.

Best,
So based on Fuyu's numbering scheme, are you looking at the FLS40XY-H2? That one would allow you to mount your own Z-motor. You could still make the improvements I mentioned above for both stiffness and coupling.

Edited to fix typo should be FLS40XY-H2

Further edit to add link:

https://www.ebay.com/itm/Linear-Motion- ... 1800712164

This looks like quite a deal for $455 and free shipping.

Another edit...I thought when I selected the FLS40XY-H2 and copied the link it would revert to that model, but you still need to select it from the drop-down menu.

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