Author Topic: Pick and place build, openpnp  (Read 4789 times)

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Offline pisoiu

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Pick and place build, openpnp
« on: September 13, 2019, 08:45:27 am »
Hi all,
I will share here my project progress, a pick and place machine. It is not designed with 'cheap' in mind, it is designed for performance. Initially I was thinking to buy a production line, but after analyzing all pros and cons, I decided to build one. It's more fun :)
Some of my goals are 1,5x1m dimensions, somewhere around 24 placing heads.
Basic components are purchased ready made (rails, servo motors, servo controllers). Mechanical parts used to join them will be built at 3d printer just to check dimensions and how they fit. After that, they will be built from aluminium at mill.
Here is one of the first tests which involves movement. In the movie is the y axis, 1 meter.

le: It is not driven to max speed (only about 2/3), nor at maximum acceleration, because the rail is not yet fixed to the table and some components are 3d printed PLA.

« Last Edit: September 13, 2019, 09:05:44 am by pisoiu »
 
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Offline tom66

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Re: Pick and place build, openpnp
« Reply #1 on: September 13, 2019, 05:44:08 pm »
I'm curious what you'll use for the feeders.
 

Offline Kjelt

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Re: Pick and place build, openpnp
« Reply #2 on: September 13, 2019, 06:00:31 pm »
Interesting will follow with utmost interest.
I also want to build one in the future, already collected a lot of 2nd hand parts for it.

So the used ballscrewspindle what is the feed somhow many mm travels per rotation.
For P&P you see a lot of 20mm feeds so very fast travel.

Do you use a stepper or servo?

24 heads, serious? Are you going too place leds or some components with the same value?
What is your thought there I wonder also since they take up a lot of space?

The linear guide looks self made, ehy not use standard wide linear rails ?
 

Offline pisoiu

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Re: Pick and place build, openpnp
« Reply #3 on: September 13, 2019, 07:38:32 pm »
Outside area can accommodate up to ~80 yamaha cl feeders. Inside area will keep the rest, whatever openpnp supports. Tray, cut tape, etc.
Ballscrew is TBI 2550, 25mm diameter, 50mm travel per rotation.
Motors are panasonic servo, minas a6, 400w high inertia. Steppers are not even close to this design's requirements. What you see in the above movie is travel at 2000rpm and 100ms acceleration time.
Head numbers is due to the fact that I want to avoid nozzle change (I am thinking at juki now), therefore I must have a combination of all sizes required by most designs. They will not be all in line, rather a matrix of 6x4 spaced at 30mm.
Linear guide is not self made, it is ISEL LFS series. It is bigger than common rails used in pnp machines but I prefer that part a bit oversized for now since the entire machine is quite big.
Everything is mounted on a 20mm thick aluminium plate.
 

Offline Kjelt

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Re: Pick and place build, openpnp
« Reply #4 on: September 13, 2019, 08:41:31 pm »
Very impressive hardware  :-+
50mm per rotation, that is a lot. How many pulses per rotation does your servo-encoder provide, or put differently what is the resulting positioning resolution?
 

Offline pisoiu

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Re: Pick and place build, openpnp
« Reply #5 on: September 13, 2019, 09:08:49 pm »
Encoder for minas a6 series has 23 bits, so positioning resolution in my case is 50mm/2^23...enough. In practice, positioning is worsened by ballscrew, it is a C7 precision class, this one was expensive enough. I didn't wanted to go to C5 or better, those have astronomical prices.
For now I am using motor's encoder but if during tests I will notice significant positioning deviations due to ballscrew heating (which cannot be compensated by motor's encoder), I will use external linear encoder, most probably magnetic type.
 

Offline Kjelt

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Re: Pick and place build, openpnp
« Reply #6 on: September 13, 2019, 09:29:38 pm »
An external linear encoder came to my mind also. I am however unsure how to connect that to openPnP. OpenPnP just sends G codes with absolute coordinates to move to right? So then you need to build a circuit with a microcontroller that reads the external linear encoder for the current position and returns that to OpenPnp, or it has to solve the delta on its own and sent extra pulses or 0-10V output to the servo driver. I am unsure how that exactly works with OpenPnP.
 

Offline pisoiu

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Re: Pick and place build, openpnp
« Reply #7 on: September 13, 2019, 09:36:28 pm »
External linear encoder connects directly into the servo driver and it's its job to deal with it. Positioning commands are taken from gcodes sent by openpnp by my driver board (which I have to build) and this one connects to x/y drivers on RS485 bus. Changes to support external encoder instead of motor built in encoder are made in the configuration parameters of the servo driver.
 

Offline Kjelt

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Re: Pick and place build, openpnp
« Reply #8 on: September 13, 2019, 09:39:32 pm »
Thanks, that makes sense. I use cheaper closed loop steppers but they don't have that option.
 

Offline pisoiu

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Re: Pick and place build, openpnp
« Reply #9 on: September 13, 2019, 09:46:34 pm »
Those servo drivers are monsters. They have around 500 parameters listed in the configuration windows. Of course, not all of them must be touched, but still, gives you an idea about the flexibility of the damn thing....and the possibilities to mess everything up....
 

Offline Kjelt

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Re: Pick and place build, openpnp
« Reply #10 on: September 13, 2019, 09:50:19 pm »
Uh yes that is what kind of scared me away of servos  :)
Mostly you have to tune the PID control using external software after the system is complete.
That can be quite an elaborate task what I have heard.
Luckily with a p&p machine it is not bad to have a little under or overshoot in contrast with for instance a cnc mill where your piece of work is then ruined.
 

Offline pisoiu

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Re: Pick and place build, openpnp
« Reply #11 on: September 13, 2019, 09:59:01 pm »
From what I read in the manuals, they don't under or overshoot. They measure the mechanical parameters, resonance frequency, etc. and somehow adjust the commands to the motor, to avoid oscillation around destination position. How is it doing this, it's beyond my knowledge. I think they call it 'automatic damping filter'.
 

Offline rx8pilot

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Re: Pick and place build, openpnp
« Reply #12 on: September 13, 2019, 11:49:53 pm »
This looks fun.....following.
Factory400 - the worlds smallest factory. https://www.youtube.com/c/Factory400
 

Offline Kjelt

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Re: Pick and place build, openpnp
« Reply #13 on: September 14, 2019, 08:29:22 am »
That is some sort of autotune, if it works that is excellent. It might take some time to adjust.
If you want to know a bit more about servos control loops , the s-curve, the three pids: position, velocity, torque, this was an interesting read for me:
http://www.techtrends.ru/docs/delta/servoprivody_asda_ecma_dmcnet/ASD-M/Tuning_ASDA_Series_Servo_Systems.pdf
 
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Offline Kjelt

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Re: Pick and place build, openpnp
« Reply #14 on: October 03, 2019, 09:57:18 am »
Any updates ?  :)
 

Offline pisoiu

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Re: Pick and place build, openpnp
« Reply #15 on: October 03, 2019, 10:08:43 am »
Not much, I have 3D printed some more pieces and made some tests with X axis. They are at very low speed (500rpm I think) and very low accelerations, because they are held in plastic mounts. In the next days I will install also X ballscrew and make some tests again.
I also received the mill which will be used to build the final aluminium pieces.


 

Offline Kjelt

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Re: Pick and place build, openpnp
« Reply #16 on: October 03, 2019, 11:59:13 am »
With my CNC I am running into alignment problems.
I am currently busy hours to align with a 0,001mm resolution clock.
You have used toolingplate which is much better than the aluminium profiles I use, still I can advise you before running high speeds, to check the exact alignment between linear rails and ballscrew, you can easily see it at the movement of the ballscrew it should not oscillate.
Also the noise of the balls inside the ballscrew and linear rails are good indicators.
Probably your setup is better and more stable, it looks very nice.

 

Offline pisoiu

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Re: Pick and place build, openpnp
« Reply #17 on: October 03, 2019, 12:34:03 pm »
Alignment is taken into consideration very carefully, there are adjustments methods available for all pieces. Alignment is measured both mechanically and with the servo's software, I have plots with measured torque for movement. It should be constant for all the axis length. Currently it is not, I have small random variations due to inconsistent deposition of lubricant and I also have a small oscillation due to incorrect alignment of the motor shaft with ballscrew end. 3d printed piece :).
But alignment and tuning for high speed will be done only after all interconnecting pieces will be made from metal. I use 3d printed parts only as proof of concept, to see if all fits nice and to check the manufacturability of parts within milling machine constraints.
With 3d printed parts I do not dare to go further than 1000rpm and 4-500ms acceleration/deceelration time. They are quite far from my goal, 3000rpm and under 100ms. What I do not know yet is the behavior of the other end of X axis (not the driver end), it will oscillate a little at stop. I hope I can compensate that from servo parameters and/or to ignore oscillation, hoping it will damp itself until the head arrives in pick/place position. I have a high speed camera (1000fps) camera to analyze this phenomenon.
« Last Edit: October 03, 2019, 12:43:29 pm by pisoiu »
 

Offline pisoiu

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Re: Pick and place build, openpnp
« Reply #18 on: October 03, 2019, 12:53:42 pm »
I am currently busy hours to align with a 0,001mm resolution clock.

Do you need that high resolution? I am currently working down to 10 microns, I have no way to measure or machine better than this value.
 

Offline Kjelt

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Re: Pick and place build, openpnp
« Reply #19 on: October 03, 2019, 02:31:41 pm »
Well my goal is also 10 microns so the measurement equipment should be at least a factor three better in repetitiveness. So that is about 0,003mm and that is the repetitiveness of my 0,001mm clock.
The problem I face is that I do not have a reference plate as you have. My cnc is mounted on a wooden hardboard which is absolutely not suitable as reference.
So I am thinking about upgrading to a stone (granite) plate , if I can find a good one for a good price that is.
The alignment I currently do is squareness of the bridge (with me the Y axis for you the X axis) relative to the X axis.
This takes a lot of time and I have lent a 4um/m squared block of steel for that purpose. I wanted to buy such a block but it costs thousands of €  :scared:
 

Offline pisoiu

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Re: Pick and place build, openpnp
« Reply #20 on: October 03, 2019, 07:32:54 pm »
If I understood correctly, you also plan to use openpnp. Why bother to mechanically obtain squarness when it can be compensated in sw?
 

Offline jadew

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Re: Pick and place build, openpnp
« Reply #21 on: October 03, 2019, 08:22:33 pm »
@pisoiu, nice project, will follow. I've been meaning to make a PnP myself, but it's rather low priority atm.

How much did the mill set you back? I've been looking for a similar one myself, but I gave up for now because my shop is not on the ground floor. I needed 10 um precision and was told that I can't get that without spending 6k+ (also, the recommended mill was a lot bigger than that).
 

Offline Kjelt

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Re: Pick and place build, openpnp
« Reply #22 on: October 03, 2019, 08:23:04 pm »
If I understood correctly, you also plan to use openpnp. Why bother to mechanically obtain squarness when it can be compensated in sw?
Ah yes that might be unclear, sorry,  my current machine is a CNC mill not a p&p  ;)
When the mill is finished I want to use it to build a P&P.  :)
I have two ballscrews on the two X axis and although I can correct the squareness with tandem homing it is not good to have to large offsets between the axis since this gives many forces on the rails and ballscrew spindles.
 

Offline pisoiu

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Re: Pick and place build, openpnp
« Reply #23 on: October 03, 2019, 08:45:03 pm »
My mill plus some accessories (machine vice, boring head, etc) was around 2k. Mill is orion 2.0, damatomacchine. Italian company, but it is actually made in China. Expect to spend few hundreds more on measuring tools: interior/exterior micrometers, calipers, center finder, granite table, DRO, etc. Mill is manual, not CNC. Most extras are from aliexpress. Not top quality of course, but good enough.
Then you'll have to discover the machinist inside you, otherwise you'll spend many more $ paying another trained person for that. But youtube is your friend here, as it was mine. Then you have to practice until you get some practical skills and hopefully you'll brake as few things as possible. I am at practice right now and today's lesson was that steel chips coming from mill are damn hot.
I do not have experience, but from what I saw from more experienced guys working on manual mills, 10microns are achievable with proper techniques and good understanding of tools and procedure's limits. Just copying what you see is not enough. A bigger (and more expensive) mill will certainly make your life easier (and your pockets emptier) but this not necesairly mean that you can't achieve results on cheaper machines.
Kjelt , much clearer now :). At a moment during the initial design of my pnp I thought at 2 ballscrews for Y axis, considering the relatively lengthy X axis (1.5 meters), but my brain locked when tried to imagine how to synchronize the servos for both. So I dropped the idea.
 

Offline Kjelt

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Re: Pick and place build, openpnp
« Reply #24 on: October 03, 2019, 08:51:24 pm »
Yes synchronizing servos would require synchronised communication and identically tuned servoloops I guess. My mill uses closed loop steppers and the drivers are more easily commanded by the step/dir interface. The Eding CNC controllerboard does support dual axis and tandem homing which makes it much easier.
Since a P&P does not have the large counterforces that a CNC does have, one ballscrew should be sufficient as many pro designs already have proven this in the past. So for my future p&p machine I also think of using a single ballscrew which makes it easier.
 

Offline mendez

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Re: Pick and place build, openpnp
« Reply #25 on: October 04, 2019, 12:15:17 am »
@pisoiu

That looks nice!! Keep up the good work!
 

Offline pisoiu

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Re: Pick and place build, openpnp
« Reply #26 on: October 05, 2019, 08:01:19 am »
And we have X axis:

 

Offline stoyanoff

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Re: Pick and place build, openpnp
« Reply #27 on: October 06, 2019, 05:31:12 pm »
Impressive! Congrats!
The hardware is serios! I`ll show you mein in a few days, when I`m ready with the control. But I don`t use  cartrige guides and lead screws, but rods and belts! I think your approach is better. I think I will have problems with the vibrations, but I am not sure. Your design is 100% better!
Best regards!
 

Offline Kjelt

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Re: Pick and place build, openpnp
« Reply #28 on: October 06, 2019, 05:40:01 pm »
I like the 45o tilt on the Y axis, you don't see that that much.
I only saw it on an assembleon machine once.
You like to share you're thoughts why you choose this over the standard 90o approach  :popcorn:
 

Offline SimonD

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Re: Pick and place build, openpnp
« Reply #29 on: October 07, 2019, 06:27:57 am »
Hi,
Very impressive plan! Can I ask how much money it has cost so far?
Thanks.
 

Offline pisoiu

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Re: Pick and place build, openpnp
« Reply #30 on: October 07, 2019, 08:39:04 am »
Stoyanoff,
My design may be better in regard to some aspects but is definitely worse on others, in which your design is better. As everything in life, there are pros and cons in each choice. My design is better in precision and speed than a stepper and belt design, but is much more expensive, difficult to calibrate and heavier.

Kjelt,
This approach is a result of a combination of factors. My table has roughly 1x1.5 meters in size, it is very big, table alone have around 90-100kg. This is due the particularities I need for my machine. This whole pnp business, as I see it, is focused towards high speed in medium and high production volumes. This is why we see components on feeders and those are the kind of machines designed and optimized by big players in industry. But this is not good for low volume and prototyping, and everyone who asked quotations from PCBA for 10 pcs, knows it. This is also my business, designing many different products, prototyping them in 5-10 pcs and then low production batches, up 1000 pcs. For me is critical to have a fast machine setup and possible offline setup. I cannot spend an entire day setting up a machine for 100 unique components then run the machine for 10 minutes to produce a test batch. I need that machine offline and loaded up in less than 30 minutes. Fastest I can think of is with cut tapes and some kind of standard fixtures. Not feeders. Maybe only on very common components like 100nf and that feeder stays on the machine. Cut tapes are most common when we are talking about prototyping, it is not economically feasible to buy full reels or pay re-reeling service only for 10-20 components. This is why I need big XY space, for many cut tapes and trays.
And that comes to your question about 45 degrees. That 1.5 meters X support has to be very solid to avoid deflection. The profile has 2 stainless steels bars inserted on sides. The carriage balls run on those bars when traveling. If I would placed the profile horizontally, it deflects in the middle with approx. 0.2-0.3mm only due to its own weight, not counting the head weight. If I would place it vertically, it bends and it induces oscillations when travelling on Y axis, because it is quite flexible in the direction of travel. That is why I placed it at 45 degrees, to obtain stiffness in both directions. The only other way was to use another profile type, square, but that one would have been much heavier, and this is not good for Y drive elements, supports and performance.

SimonD,
I do not have at this moment total costs, they will be accounted only at the project end. But I can give you some price examples for most important components:
-ballscrews (plus end supports and motor connector) are TBI, around $750 plus $250 shipping from China
-Panasonic minas a6 400w servos, drivers and cables for both axis, around $1000, also from China. From european distributor, one motor alone was quoted at 700 eur.
-precision aluminium table 1x1.5 meters plus raw aluminium material for manufacturing parts: $800
Then comes the interesting part of fitting all together. If you do not have a mechanical workshop at your fingertips and you don't know how to use it, prepare to spend a lot in designing and manufacturing unique mechanical parts. This is also valid for every other task which you have to put others to do it if you don't know how to do it yourself. Calibrating mechanics, configuring servos, vibration analysis, driver hardware and firmware design, optical systems design, pneumatics, integration with software, etc....
« Last Edit: October 07, 2019, 10:05:05 am by pisoiu »
 

Offline MR

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Re: Pick and place build, openpnp
« Reply #31 on: October 07, 2019, 10:15:39 am »
Seriously I think you underestimate a Belt design, my Mechatronika is very precise with a belt (in theory hah since those id**ts misconfigured the servo motors initially and we had to fix it by ourself), but they also do a reduction (can't say how much they do on the Y axis since I did not pay too much attention to it, it should be at least >2:1).
Even if you watch some high speed Siemens pick and place machines, they're also using belts. I think the idea that belts aren't accurate enough comes from inexperience.

Belt design (older Siemens, but I'm sure even that would be high level for openPNP at the current stage):





this is a stepper based system

From my point of view the only intelligent part of a pick and place machine lies in the pick and place head nowadays. The X/Y movement is nothing worth to mention anymore.



-> my opinion the X/Y movement is the easiest part of that machine.... pay attention how close the camera is, the illumination of the PCB is crucial, my Mechatronika is an utter failure with that (you can see the big distance of the camera and illumination ring in the first video) and misdetected fiducials can end up in misplaced or shifted components - and a lot re-working.



-> this one picking up all components at the same time, you might need adjustable feeders for that
I would say this is even more efficient than gatling gun pick and place heads I would say, in those areas feeders are the key point.

https://www.youtube.com/watch?v=JQcf46hquNQ&feature=youtu.be&t=21

this one needs special feeders .. it's getting expensive. some of them don't even use the regular stripe feeder anymore but just queue up the components in a slot.
I wonder if that guy also talks like that with his wife at home, freaky ad-talker.
« Last Edit: October 07, 2019, 10:21:36 am by MR »
 

Offline pisoiu

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Re: Pick and place build, openpnp
« Reply #32 on: October 07, 2019, 11:00:16 am »
I do not have practical experience with belts on pnp, so yes, I may have some misconceptions. But what I see is that many manufacturers move from belt to ballscrew. In my unexperienced opinion, the accuracy of a belt design has not much to do with the belt itself being imprecise by construction, rather with the fact the material has some elasticity and that creates oscillations when using short acceleration and stopping times. Of course, that can be mitigated by proper servo tuning, using of external encoders, etc. but before being mitigated, designer must have means to analyze them and that can be done only with accelerometer based instrumentation or with high speed camera. Manufacturers, perhaps, have such tools. DYI builders most probably don't.
I have some experience in the past with transmissions with belt in other systems and I found them difficult to purchase and the variety was not as wide as ballscrew's. Also, the design of the drive/support ends is a bit more complicated for me, compared with ballscrew, which has all components readily available, aliexpress/alibaba is full of suppliers.
Otherwise yes, XY movement is the least challenging part, I expect to be a little difficult only at servo configuration and tuning.
Vision system will be with coaxial illumination, ethernet camera on head and usb camera on bottom. I have already built and tested a rough prototype. Currently, openpnp cannot work with multiple component cameras, so for the moment I'm stuck with one. In the future, I plan to develop a fly vision camera to speed up things.


LE: your M80 have one nozzle travelling over...don't know exactly, say 50cm from the videos? Mine will have 24 nozzles (hopefully) over 150cm. I would need a pretty wide belt :)
« Last Edit: October 07, 2019, 11:29:50 am by pisoiu »
 

Offline SMTech

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Re: Pick and place build, openpnp
« Reply #33 on: October 07, 2019, 11:32:41 am »
Most bigger machines stopped using belt a while ago, these days cheaper machines use ball-screw and more expensive ones use linear motors. Linear motor options are often promoted as a zero maintenance option.

On our Essemtec it is suggested the 30mm X belt is changed every ~2 years (but this will depend on usage, 5+ seems more common as far as I can tell) on a Paraquda at least Y is driven by belts on both Axes and these last 10+years, although again Essemtec would like you to change them more regularly. When the belt fails you will hear the gantry vibrate when it moves, all the belts can be tensioned & the tension is checked by measuring the resonant frequency by plucking it. On these machines there are linear encoders on both Y axes as well as X, the location from all of these is fed back to the servo controller. A full calibration of the machine maps the location of a glass plate covered in fiducials against the encoder data.
 

Offline Kjelt

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Re: Pick and place build, openpnp
« Reply #34 on: October 07, 2019, 12:51:32 pm »
AFAIK belts can be equally precise as ballscrews but they have some disadvantages, the tension is falling after time so you need auto tension mechanisms and they wear out much quicker than ballscrews.

Also with ballscrews you need to weigh speed vs accuracy, they are available in 3mm travel per rotation upto over 20mm travel per rotation. If your servos or closed loop steppers are accurate enough it does not matter and you often see the larger travel per rotation ballscrews used in p&p machines to optimize for travel speed.

Linear motors are the ultimate but very expensive and quite dangerous if you are doing the pid control loop on your own.
 

Offline MR

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Re: Pick and place build, openpnp
« Reply #35 on: October 07, 2019, 01:23:24 pm »
Linear motors are the ultimate but very expensive and quite dangerous if you are doing the pid control loop on your own.

After my experience with the Mechatronika machine (which is using Delta Servo Motors) I can say that those motors are pretty easy. There's almost nothing you can do wrong if you're careful enough.
A completely misconfigured PID will result in a controller shutdown of the motor.
So you just need to take care that you won't run against the boundaries of the machine.

The other question:
The mx80 has a travel distance of around 50cm.

After all my experience with the machine I can say all Mechatronika really sells is the machine (at a cost which just does not justify anything they sell) ... but for a successful manufacturing ability you'll need much more...

a) stencil mask printer, and experience with solder paste
b) component management
c) maybe AOI, depending on what you want to do

The big limitations of our machine:
- I need a tray feeder, we're currently juggling trays manually it's okay but I don't like that. There's a commercial company (probably the first one you'll find on youtube) which sells one tray feeder for 20.000 EUR (yes right, 20.000 EUR). I'm not going for that, I'd rather do it myself with a few steppers and a 3d printer for prototyping.


If you would have done a portal design with the portal being longer than the Y rails you could pick the components from outside of the portal.

See:


That's all stuff you learn once you juggle with feeders :-) Yamaha CL Feeders seem to be okay (I'm just starting with it and building an adapter for my mechatronika mx80).

One problem you definitely cannot have is parts falling into the machine, the Mechatronika MX80 is braindead when it comes to that, you cannot get things out of the machine without special tools. We have already modified the machine so we can get inside it.
 

Offline SMTech

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Re: Pick and place build, openpnp
« Reply #36 on: October 07, 2019, 01:56:18 pm »
Trays represent a major issue to anyone who has multiple ICs that come packaged in trays on a single design. Its true for pretty much any vendor. Typically there is a basic option that uses up around 30 feeder slots and hold two trays, sometimes there might be an intermediate option where a feeder cassette that uses fewer slots can be loaded and it can alternate between ~6 trays, this is an option I've seen on Dima for a reasonable price & I think Fuji do it too, some devices in trays can be quite light so the mechanism needs to be smooth so nothing jumps out of its pocket. The next option is your more typical filing cabinet sized tray changer, £20k is a pretty good ballpark price I think, these can hold lots of trays so you are covered both from a volume and multiple device type perspective.

Two machines take a different approach, Europlacer have the option to fit a tray inside the machine over the conveyor that holds 10 trays and Hanwha have a tray feeder that feeds from beside the machine so uses no feeder slots. I think some Yamaha/iPulse machines have(or the option to) a tray area inside the machine possibly at a cost to max PCBwidth.
 

Offline Kjelt

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Re: Pick and place build, openpnp
« Reply #37 on: October 07, 2019, 02:10:47 pm »

Linear motors are the ultimate but very expensive and quite dangerous if you are doing the pid control loop on your own.

After my experience with the Mechatronika machine (which is using Delta Servo Motors) I can say that those motors are pretty easy. There's almost nothing you can do wrong if you're careful enough.
I was talking about LINEAR motors.
Those do not have any physical resistance (like a ballscrew or belt) which can slow rhem down, they can easily do 20G acceleration.
I have seen the damage it could do , a 1m linear motorcarriage went right through 20mm aluminium endplate.
 
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Offline MR

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Re: Pick and place build, openpnp
« Reply #38 on: October 07, 2019, 02:31:12 pm »
I was talking about LINEAR motors.
Those do not have any physical resistance (like a ballscrew or belt) which can slow rhem down, they can easily do 20G acceleration.
I have seen the damage it could do , a 1m linear motorcarriage went right through 20mm aluminium endplate.

oh thanks didn't know about those yet! However I really think that the X/Y configuration is just one part and not the bottleneck of a fast pick and place machine ... far before that the bottleneck will be the pick and place head and feeders.
« Last Edit: October 07, 2019, 02:35:12 pm by MR »
 

Offline Kjelt

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Re: Pick and place build, openpnp
« Reply #39 on: October 07, 2019, 03:00:39 pm »
I agree on that.
It amazes me that there are little new innovations in the feeder field.
Paper tapes with plastick cover is just so clumsy.
Only the bulk component  piezo shakers which are rediculous expensive are new developments.
 

Offline SMTech

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Re: Pick and place build, openpnp
« Reply #40 on: October 07, 2019, 03:32:55 pm »
Where do they evolve too? Tiny parts with tiny legs and an orientation need to be presented to the pick head somehow in a predictable fashion without being at risk of damage, I don't think there is a way round tape with pockets for many items. The piezo thing could perhaps be extended to more parts 2-pin if you could make that feeder just as small as a tape feeder but those bulk parts, come in a tape its just there's a whole lot more in each pocket.
 

Offline Kjelt

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Re: Pick and place build, openpnp
« Reply #41 on: October 07, 2019, 05:35:15 pm »
True for asymetric and fragile parts but for the jellybean resistors, caps and diodes it is such a shame.
For resistors the time to sort , package plus packaging material itself outweighs the component costs, silly huh?
But I am going offtopic so will let it rest.
 

Offline pisoiu

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Re: Pick and place build, openpnp
« Reply #42 on: November 29, 2019, 04:52:41 pm »
Little by little, final aluminium machined pieces are coming together.
First Y test with aluminium parts, speed and acceleration at maximum.
 

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Re: Pick and place build, openpnp
« Reply #43 on: November 29, 2019, 05:37:22 pm »
And this is how stopping looks like at 1000fps. Servo driver is not tuned, it will be only in final mechanical configuration.
 

Offline stoyanoff

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Re: Pick and place build, openpnp
« Reply #44 on: December 05, 2019, 08:09:20 pm »
How does your acc profile look like? For mine I`m using 1/3 of the distance for acceleration and 1/3 for deceleration. I have no time to tune this, but now even when I use speed like 7000 the machine acc and dec smoothly and causes no vibrations.
I haven`t made clips of my machine, because I made a stupid mistake - I`ve tried to use a simpe camera(USB HD) insted of the industrial once suggested by  openpnp. And now my  machine doesn`t see anything.... Don`t do it! I have to setup everything manually and it is not great..
Best regards!
 

Offline pisoiu

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Re: Pick and place build, openpnp
« Reply #45 on: December 06, 2019, 06:20:58 am »
Hi,
Acceleration profile in my drivers is based on acceleration times and max rotational speed, not travel distance. What you see in above movie is with 10ms acceleration/deceleration time and max speed at 4000 rpm. The max speed is only achieved on longer distance, not on small steps. I did not actually measured 10ms acceleration time to see if it's really there, there is also a torque limiter which may be activated during acceleration. I tested this at max speed to see if it holds together, but a complete analysis and tuning will be done only when all pieces are there for both axis. Driver software has very nice tools to help with that, you can plot a lot of graphs with every imaginable parameter from the motor.
As for cameras, my top camera is an ethernet camera due to long cable, 2.5m at least. I know it has delays and low frame rate but I don't really care as it is used in production only for fiducial recognition, few hundred ms there won't make difference. But I need immunity on noise. Bottom camera is usb3.0 but I plan to use isolators on all usb's (camera and controller) , to avoid interference from noise sources. Internal communication between main controller and head electronics will be CAN, between controller and servo drivers is RS485, also due to immunity reasons.
« Last Edit: December 06, 2019, 06:33:33 am by pisoiu »
 

Offline Styno

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Re: Pick and place build, openpnp
« Reply #46 on: December 06, 2019, 08:38:50 am »
What are your reasons to use CAN for the head and RS485 for the feeders? I know RS485 only handles OSI level 1 and CAN level 1 & 2, but I'd like to know why you don't choose one over the other to reduce adding complexity in the machine communication (besides already using Ethernet and USB)?

Do you need CAN stuff like message prioritizing?
« Last Edit: December 06, 2019, 08:40:45 am by Styno »
 

Offline pisoiu

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Re: Pick and place build, openpnp
« Reply #47 on: December 06, 2019, 09:52:55 am »
Hi,
CAN is chosen because of noise immunity, this is the first reason. Data cables are long, over 2.5 meters and in parallel with switching high current cables for servo. I have here available many MCU used in other projects of mine with CAN interface, second reason. I have good experience in writing firmware for CAN devices, third reason. Low latency, hardware address filtering, communication based on low quantity of data, automatic CRC processing, support for many nodes, fourth reason. CAN will be used between main controller to head electronics and main controller to feeder banks.
Servo controllers I use (panasonic minas a6) have a choice between standard multi-signal interface (step, direction, etc) and commands over RS485 using their protocol. It is easier for me to talk with drivers over RS485, less wires used, better noise immunity, much better control flexibility, as I have access to all servo parameters, status, errors, etc.
« Last Edit: December 06, 2019, 10:14:15 am by pisoiu »
 

Offline nisma

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Re: Pick and place build, openpnp
« Reply #48 on: December 25, 2019, 02:48:27 pm »
As info, without being related to it.
https://www.crowdsupply.com/citrus-cnc/simplepnp
It seems that there make some additional changes to lower the price.
It already have some serious design flaws for saving small $ on certain components but overall the is not bad and price with 3d printed feeder is not bad.
Certainly it depends if the company is registered to export where the vat and machine could be deduct from taxes, otherwise Chinese Machine is in the end cheaper paying less then double that price. This for professionals.
For hobbyist this don't matter.
 

Offline Kjelt

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Re: Pick and place build, openpnp
« Reply #49 on: February 14, 2020, 11:31:17 pm »
Any updates or progress pisoiu ?  :popcorn:
 

Offline pisoiu

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Re: Pick and place build, openpnp
« Reply #50 on: February 15, 2020, 09:43:20 pm »
Hi,

There are some, but not very spectacular (meaning no videos).
I worked hard at mill to complete the aluminium parts required to mount everything needed for x-y assembly. There are still few parts to be built and I expect at least a month until I have something moving.
I also built a controller required to interface everything with openpnp. It will talk with servo drivers over modbus RS485 and will send all data to head assembly over CAN.
I tested a laser alignment system for small components, it works fine, basically any component with biggest cross section smaller than 7mm will use laser alignment for placing, not camera. That will be done on route from picking coordinates to placing.
The bottom camera is now in building process, and I think I will include in it, besides the coaxial illuminator, a laser displacement sensor, to measure component height in the nozzle.
That's it so far.
« Last Edit: February 15, 2020, 10:30:17 pm by pisoiu »
 
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Offline Kjelt

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Re: Pick and place build, openpnp
« Reply #51 on: February 15, 2020, 11:08:05 pm »
How does your laser alignment work, is it a oem piece or did you do something yourself?
20 years ago they did it like this
https://www.eevblog.com/forum/projects/tear-down-of-an-assembleonphilips-pp-head/msg1293815/#msg1293815
 

Offline rx8pilot

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Re: Pick and place build, openpnp
« Reply #52 on: February 16, 2020, 12:14:50 am »
How does your laser alignment work, is it a oem piece or did you do something yourself?
20 years ago they did it like this
https://www.eevblog.com/forum/projects/tear-down-of-an-assembleonphilips-pp-head/msg1293815/#msg1293815

On my Quad 4000C - it uses a laser scanner and a CCD line sensor. All analog upfront that gets digitized for comparison. For its age - it works really well. Guessing modern tech could do the same thing for pennies at 100x the resolution. This method is really fast and travels with the head so the up-camera only gets used for fine pitch BGA's.

Someday, I will be forced to convert my Quad to Open PNP as the old hardware dies out and the software becomes a problem. That would be a fun and exhausting project.
Factory400 - the worlds smallest factory. https://www.youtube.com/c/Factory400
 

Offline pisoiu

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Re: Pick and place build, openpnp
« Reply #53 on: February 16, 2020, 02:27:36 pm »
It is built by me. The head is not built yet, I only tested the concept on the bench, a laser diode (7mw red, nothing special about it), a lens colimator and a line scan sensor 128 pixels, 8mm active area (tsl1401). The laser light must be as wide as the sensor and it's critical to be parallel. It will work exactly as in the video shown by you.
 

Offline Kjelt

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Re: Pick and place build, openpnp
« Reply #54 on: February 16, 2020, 06:42:34 pm »
If you would like a few of the Cyberoptics units from the Assembleon machine I can sent it to you for free, maybe some optics to be re-used? I have no idea if that would be usefull.
 

Offline pisoiu

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Re: Pick and place build, openpnp
« Reply #55 on: February 16, 2020, 07:07:48 pm »
Hi,
Thanks, I do not want to entirely dismiss the idea, but to be honest I prefer to build everything with aliexpress components, this way, if something breaks, it will be easy to fix or cheap enough to build a new one. It is also essential to use that line scan sensor, it is the only one with low cost and SPI access, this way allowing me to control the entire head with an 8051 MCU. I have good experience with this family and I write everything in ASM to have control to the last instruction cycle. This level of control is also required because the Z actuator for head position will probably be a voice coil linear actuator, which I have to build a prototype and test yet. For that one I need also to write a control loop in 8051 firmware.
 

Offline rx8pilot

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Re: Pick and place build, openpnp
« Reply #56 on: February 16, 2020, 08:05:13 pm »
What is the cost of that sensor?
Factory400 - the worlds smallest factory. https://www.youtube.com/c/Factory400
 

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Offline RoGeorge

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Re: Pick and place build, openpnp
« Reply #58 on: February 16, 2020, 09:41:12 pm »
Optical mouse sensors are cheap too, also fast, many can be used as low resolution high fps camera.  Didn't followed the thread closely, so might be a dumb suggestion. 

Offline rx8pilot

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Re: Pick and place build, openpnp
« Reply #59 on: February 16, 2020, 10:50:39 pm »
It is built by me. The head is not built yet, I only tested the concept on the bench, a laser diode (7mw red, nothing special about it), a lens colimator and a line scan sensor 128 pixels, 8mm active area (tsl1401). The laser light must be as wide as the sensor and it's critical to be parallel. It will work exactly as in the video shown by you.

The resolution seems to be modest - do you suppose that will be a practical limitation? I guess it should get the alignment close enough for most parts - perhaps a challenge as the parts get small.
Factory400 - the worlds smallest factory. https://www.youtube.com/c/Factory400
 

Offline pisoiu

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Re: Pick and place build, openpnp
« Reply #60 on: February 17, 2020, 06:55:57 am »
True. Not great but not terrible either. With this sensor I get a measuring error of +-62.5 microns. I could have used better but... bigger sensors (in terms of size and/or resolution) comes with several problems. I would need a wider laser beam, that complicates optics. Greater resolutions are much more expensive , both the sensor itself and the required interfacing. Most have analog output, they need timing circuits, adc, etc. I have also size constraints, everything must fit in a 30mm square. This one seem to fit my needs, hopefully with good results at least to 0402. When I'll have a prototype, I will see..
RoGeorge, for this kind of application, a linear sensor is required. Having 2d sensor would not help, it just complicates optics. The optic mouse sensor itself have a very low resolution (in the range of 20x20) and the array is very small. It is mandatory in this case for the sensor to have the reading area in 1:1 ratio with the object you want to analyze.
« Last Edit: February 17, 2020, 07:05:27 am by pisoiu »
 


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