Pulsing with Robot

[john]

I am recently new to working with Kuka PRC. I am wanting to weld with the robot and was wondering how I could pulse with the robot. I am hoping to extrude the weld and create an object, so I am assuming I need to figure out how to make the robot pulse. Any ideas would be helpful. Thanks!

[Johannes @ Robots in Architecture]

Hello John,

I'm very sorry, I must have mussed your post before.
I'm not really an expert on welding, so what exactly do you mean by "pulse"? You can pulse the robot's digital output, sending a brief 24V signal over a defined number of seconds.
KUKA|prc contains a "Custom KRL" component where you can input any KRL code you want, for the pulsing it would be e.g. "PULSE($OUT[1],TRUE,0.1)" - that would enable the digital output 1 for 0.1 seconds.
Is that what you are looking for?

Best,
Johannes

[john]

Hey Johannes,

No worries, thanks for getting back to me. I think you're right, I need to use the Custom KRL component to achieve what I am wanting to do. Three things:

1. Basically what I am wanting to do it extrude using a welder. So I am trying to figure out how to account for the robot "pulling the trigger" on the welder to create a bead of weld and repeating that process. That's what I am referring to pulsing as. I am wanting to do something similar this: https://hackadaycom.files.wordpress.com/2014/02/robot-printer.jpg?w=800&h=389

2. I think it is similar to Tutorial you posted "Example: Extrusion Process" except I can't load the full script because I have a newer version of PRC. The version I have is 2016-02-21.

3. One last thing. Do you know how I can lock an axis on the robot? I am wanting to lock the 5th axis.

Thanks for the response and your help!

[Johannes @ Robots in Architecture]

Hello John,

There is also an extrusion example for the new KUKA|prc, however I don't think that it will be of very great help as your project is a bit different.
From the robot programming I don't see a particular problem - the challenge will be getting the material and timing exactly right.
Why would you want to lock an individual axis? You cannot really do this with a 6-axis robot - the next best thing would be to use axis movement that do not change the A5 value.

Best,
Johannes

[john]

-When I open the zip file for the extrusion example it says that it is for an older version. I only saw one zip file on the tutorial page. I wasn't sure if it would be helpful,just wanted to see more or less the set up of  components used for it.

-Do you have a suggestion for how to set up the timing? Starting to get an understanding of all the PRC components but still could use some direction.

-Someone that we told our initial idea of wanting to extrude with the welder told us that we would want to lock the 5th axis and it would help with what we were trying to do. He works with I believe powermill.... Not sure if that changes anything....

[Johannes @ Robots in Architecture]

Hello,

That's the link I'm referring to: http://forum.robotsinarchitecture.org/index.php/topic,264.0.html
Timing depends of course on the speed, but you can also use commands like WAIT SEC 1 to stop the robot for a defined time.
I may be missing something here, but I don't see ANY advantage in locking A5 - there are robots with just 5 axis, but they don't skip the A5 either: http://www.kuka-robotics.com/en/products/industrial_robots/small_robots/kr6_r900_fivve/
So I guess that the locking of the A5 probably refers to some kind of PowerMill specific functions that does not actually "lock" the A5, but probably constrains it somehow.

The advantage of a robot is exactly the kinematic flexibility compared to 3-axis machines (as you can tilt and rotate the tool) but also compared to 5-axis machines (as you can rotate your tool around its own tool axis, thus avoiding collisions and other problems).

Best,
Johannes

[john]

Yeah, locking that axis seemed sorta odd to me. That tutorial works! Thank you.

I will try the wait component and see what I can do with it.

Thanks again for all the info and help Johannes! I'm sure I will be bugging you again soon!

[Johannes @ Robots in Architecture]

Don't hesitate to do so!
All the best!

[john]

Hey Johannes,

So I think I have it set up to make the robot "weld" but I have run into another issue. The robot has no problem when it is working with a line that is parallel or perpendicular to the xy plane, but as soon as I add a curve to the line or it is no longer perpendicular, the robot turns red and can no longer follow the curve. I have the planes so they are oriented to follow the curve, but as soon as they try to "weld" on a point where it is not perpendicular it has an issue. Sorry if I sound confusing, I have an image to accompany this. Any suggestions on what I can do to fix this?

[Johannes @ Robots in Architecture]

Hello,

Well, on the first screenshot you are at the limit of A6, which is +-350 with the Agilus. You can set it to infinite rotation, though as you need a power supply for your tool, it probably doesn't make much sense. In the more recent member version, setting the axis limit of the simulated robot to infinite is possible as well, by the way.
In the second screenshot, the robot simply cannot reach the programmed position anymore.
If you send me the files to johannes@robotsinarchitecture.org I can take a look at them!

Best,
Johannes