Screwing application with UR

Etienne_Samson

We have a customer looking to screw with a UR.

Is there any screwing gun that can be easily interfaced with the robot?

Electric screwdriver vs infinite rotation of the last joint, what to do and what not to do?

Ryan_Weaver

Certainly @Samuel_Bouchard  - 

While using the infinite rotation on the UR3 Wrist 3 sounds appealing, it isn't very practical as a screwdriver.  The torque resolution is very coarse and speed can be slow.

We decided to work with Kolver because they are a local company who offers a variety of screwdrivers, feeders and torque controllers at a very competitive price when compared to alternatives we had looked at.  The speed/torque clutch out routines are stored in the controller, then called via I/O from the robot.  That means you can handle multiple different screws without changing out tools as long as the bit is compatible.  The pluto screwdriver is small, lightweight and was easy to design an interface plate for.

The actual application programming was pretty simple - standard UR force control takes care of the "screwing" action very well.  The most challenging part was getting the screw feeder to present the screws in a repeatable position.  The version we have in the video isn't truly a "robotic" feeder, it's meant for manual feeding by a person.  In order for the screws to vibrate down the track, it has to be free standing, which means it can vibrate around on the table.  The video gets the concept across, but in reality, we would probably use a feeder specialized for robots.

gerenga

Samuel_Bouchard said:

@gerenga what was your approach in the following integration?

https://www.youtube.com/watch?v=cTIdm5XpWf8

Still Thailand so budgets are often tight and we are still at industry 2.0 in many cases so we have to be more realistic about customer needs.
Simple approach here is to show a first step low budget automation with UR.

Many of our customers already use a screw feeder and a auto screw driver so we wanted to show how easy it is to make the first automation step. Take a UR3, attached your available system, put your part in a jig where it usually is anyways and go.

In this case the customer has to invest only in the robot which makes the decision often easier. However beside it being a "quick & dirty" solution it has a few nice side effects.
Often the screw drivers are calibrated and there are fixed routing plans for the production procedure. We do not violate any of these so a lot of resistance for implementation doesn't happen in the first place as all the "nasty" documentation updates are not required to get going. Sometimes we have to make it as simple as that.

To market this further we just set up the application for the exhibition as people can relate to this process. However to not having to support this station in any way we decided that we want it running fully independent but screws in and out doesn't really show the repetitive action we wanted to show. So we decided to use a Zimmer group electric gripper and put the threads into the gripper fingers to show the Zimmer gripper precision as well. You may see some marks at the gripper finger threads but the counter was about 10,000 pieces when the video was done.
We have similar experience like Ryan regarding the manual screw feeder so we just locked it in place via aluminum profile still allowing vertical vibrations which fixed this issue.
We then had the topic that we wanted to show process control and a certain self diagnosis regarding our stations so we added a fiber optic sensor which confirms whether we actually picked up a screw because there is no interface between the screw feeder and the robot. However to make it a bit more obvious and fancy we relocated the sensor away from the pick up position to the side just for the show. In case the fiber optic sensor doesn't find a screw the robot will run another pick up cycle. Then we simply fasten the screw and beside checking the robot position when finished fastening, however to confirm that we don't actually still have a screw mounted on the tool when we go for another pick up run, we go to the sensor again and trigger a popup in case of detection to show self diagnosis functionality.
We are using the force mode as well as it is just that simple.
Once all screws are set, which is handled by variables in the robot program, the gripper opens and the screws fall back into the screw feeder. This is simply to keep the system running without the need to load or unload any material on the exhibition.

It's simple but effective.

Best regards,
Enrico

Samuel_Bouchard

@Ryan_Weaver can you share your experience with this integration?

https://www.youtube.com/watch?v=uaGXoWPUXJI

Samuel_Bouchard

@gerenga what was your approach in the following integration?

https://www.youtube.com/watch?v=cTIdm5XpWf8

matthewd92

We have not done screwdriving yet....coming in the very near future but we do a lot of work with hand tools.  We have developed a holder that allows us to use tools that are designed to work with human hands with a Model 85 2 finger gripper, this approach allows us to have work cells with several tools in it and use them all with the same gripper.

In this application we have 2 pneumatic drills, a soldering station and a silicone dispensing syringe (orange tool gripper).  All of these tools are driven over simple I/O with the robot.  The Loctite dispenser actually has a robot I/O port which made it easy and actually gives feedback that the unit is running.  You can do manual operation or timed dispense, we use it in manual mode as it's just easier for what we are doing.

gerenga

Ryan_Weaver said:

Certainly @Samuel_Bouchard  - 

While using the infinite rotation on the UR3 Wrist 3 sounds appealing, it isn't very practical as a screwdriver.  The torque resolution is very coarse and speed can be slow.

We decided to work with Kolver because they are a local company who offers a variety of screwdrivers, feeders and torque controllers at a very competitive price when compared to alternatives we had looked at.  The speed/torque clutch out routines are stored in the controller, then called via I/O from the robot.  That means you can handle multiple different screws without changing out tools as long as the bit is compatible.  The pluto screwdriver is small, lightweight and was easy to design an interface plate for.

The actual application programming was pretty simple - standard UR force control takes care of the "screwing" action very well.  The most challenging part was getting the screw feeder to present the screws in a repeatable position.  The version we have in the video isn't truly a "robotic" feeder, it's meant for manual feeding by a person.  In order for the screws to vibrate down the track, it has to be free standing, which means it can vibrate around on the table.  The video gets the concept across, but in reality, we would probably use a feeder specialized for robots.

Any issues regarding the kolver system? I'm looking into an affordable system for my customers regarding proper torque control. However I find it rather difficult to find a system which allows to do proper tracking of the process regarding feedback to a quality control system. We use the robot absolute position to confirm full fastening as well but can you at the kolver system actually get a value or log to handle? Present programs are a good thing but I still look for a system to send actual parameters to the fastening unit. I'm nearly on a point to design our own system but don't want to reinvent the wheel if someone already has a solution which is doing the job.

Thanks for the feedback.

Ryan_Weaver

@gerenga - I don't have much to complain about with the Kolver system, but we're certainly still learning.  There is a serial interface to capture torque reporting for QC systems, so with a little development you could have a solid log interface on a PC.  

The torque/speed profiles are saved in the screw controller in 8 different programs.  We call them via IO, but there may be a way to change them over TCP.  I would recommend you give them a call, they've been very accommodating with us.

gerenga

@Ryan_Weaver , Thanks I'll have a look

Samuel_Bouchard

@yuvarajoo what are you using on your side?

https://www.youtube.com/watch?v=97mO2oa6Nsk

Samuel_Bouchard

Here is another example from @MKarabin. Matt, which screwdriver are you using? How did it integrate?

https://www.youtube.com/watch?v=iTCZs_qjnLc

https://www.youtube.com/watch?v=ebpmVpFzWfM

Sebastien

@MKarabin this is really nice I am curious to know what feeder did you use for the screws. It seems to work well!

matthewd92

Sebastien said:

@MKarabin this is really nice I am curious to know what feeder did you use for the screws. It seems to work well!

Looks like a system made by Kolver USA.   http://www.kolverusa.com/products-list/12-Automatic-screw-supplier

@MKarabin how is the cost on this system?  We have a couple opportunities that could benefit from a system like this  

MKarabin

The first video we did was for a customer application. They currently use a Delta Regis screw presenter and a pneumatic Deprag Minimat driver (both seen in the video) for their non-automated screwdriving. We went with that so they can easily add in the UR and keep all of their existing equipment. The screw presenter seemed to work fairly well, but it was possible to double up on screws presented or have it hang up to where no screws were there which is why we had the Cognex sensor checking for screws. This was fairly rare though.

The second video is indeed a Kolver as @matthewd92 mentioned. I did not personally work with that unit. One of my coworkers was using it. His initial thoughts were very positive though. You can control speed, direction, and torque and have up to 8 different programs. He also said it is very quiet. I don't think he is a member here, so I'll see if I can get more information from him. 

Edit: Found out he is already a user. @acmonteith Andy can you provide any info on the driver you were looking at?

acmonteith

Yes, this was a Kolver screwdriver, controller, screw presenter as well as the mounting plate and control cable for the screwdriver. Total kit price is about $6K. Let either Matt or I know if we can provide you with a quote or other information.

Sebastien

@Ryan_Weaver in this screwing application you mentioned using the UR force mode. What kind of setup in the force mode are you using. Only applying in Z or do you also have compliance in x-y?

yuvarajoo

@Samuel_Bouchard noticed this topic. Basically we are using Kovler multitorque screw driver unit with its controller. It has IO points at it's controller and gives signal when defined torque achieved. We even use force and position feedback for depth control.

Etienne_Samson

@yuvarajoo can you tell me which model you have been using? I would like to get that screwdriver to do some demo in our lab. thanks !

Ryan_Weaver

@Sebastien yes, it was just force in Z, no compliance in X-Y.  As long as we got the screw tip nice and perpendicular to the tapped hole, it worked smoothly.  Also it was really helpful to have a lead-in chamfer to make sure the scew gets into the hole before spinning

yuvarajoo

@Etienne_Samsonwe we are using Kolver Controller EDU series with CA series electric screwdriver. The model need to select according to torque required and also the functionality of the controller. Best if your side can contact local Kolver supplier for recommendation.

Etienne_Samson

@yuvarajoo thanks!

vidzz

Hi, We are planning to use Kolver controller(EDU 2AE/TOP) for screw driving application with iiwa robot. Anybody having experience with iiwa for this application? Or any suggestions on what could be a better Kolver model for ease to communicate with robot controller? 

@Ryan_Weaver is the communication using the kolver model in the new axis england application(EDU 2AE/TOP/E) simple? As you mentioned it is done via the IO's available on the kolver controller.
As iiwa robot controller uses EtherCAT as a communication bus so I was looking for what could be a best interfacing method to the Kolver controller.


Thanks.

Ryan_Weaver

@vidzz - I expect that I/O would be the best method for an iiwa as well, since the Kolver controller doesn't support EtherCAT.  

vidzz

@Ryan_Weaver Thanks!

kschong

Hi, is there URCAP for Kolver Torque driver ?