Author Topic: Unexpected collision detected  (Read 63 times)

yyh1002

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Unexpected collision detected
« on: May 14, 2020, 06:50:39 AM »
Hi,

I'm experimenting with the collision check function.
I tested the example collision file by Johannes and ran into some issues.
I'm only asking the robot to check the collision of itself, without any additional fixture.

1. The core is showing collision between simulation slider 0.8-1.0, when everything looks fine. It's showing collision between the tool and A6 (Tool 1.png).
So I tried swapping the default tool with a custom tool without geometry. The empty tool got rid of the collision error. (Tool 2.png)
Can someone help me understand what is causing it? I tested in another file with turntable function, it is even showing A6 collision for every command.

2. I also don't quite understand what the option "In Background" after "Collision Checking" does.
It seems that enabling it removes all collision detection, not even showing up in analysis.
If I have "In Background" ticked, where can I find the collision result?

PRC version: 2019-10-09

Thanks,
Ryan

Johannes @ Robots in Architecture

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Re: Unexpected collision detected
« Reply #1 on: May 14, 2020, 09:27:16 AM »
Hello Ryan,

I just checked the file you attached and it seems not to show any collisions on my PC. Just to make sure: 0.8-1.0 is showing up red on your version?
I need to look into the source code, but I don't think that we check for collisions between A6 and the tool, as they are always connected anyway. But maybe some part of the tool is reaching into A5?
Regarding the in-background option, the idea is that you see the toolpath without collision checking first and that it then calculates the collisions in the background. However, Grasshopper is very particular about updates that do not originate from its own graph, maybe something got broken there. I'll look into it.

Best,
Johannes

yyh1002

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Re: Unexpected collision detected
« Reply #2 on: May 19, 2020, 04:52:24 AM »
Hi Johannes,

Strange. When I posted this thread, 0.8-1.0 showed the tool and A6 ring as red.
I looked at the analysis output, the collision code is showing 1 for index 5, which I think means A6 collision.
I run the exact same script today, and it seems the problem is gone. No longer showing collision warning.
But then I tested my other script with turntable, it still have the collision warning. And it's showing collision for every move, as shown in the screenshot.
Can you please take another look at it?

Thanks,
Ryan

Johannes @ Robots in Architecture

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Re: Unexpected collision detected
« Reply #3 on: May 19, 2020, 01:03:47 PM »
Hello,

Thank you for reporting the problem, I think that I've identified the issueand fixed it in the most recent member version: https://forum.robotsinarchitecture.org/index.php/topic,1117.0.html
I've just uploaded the file a few minutes ago.

Best,
Johannes