Curve intersection / geometry tolerance problem

Kevin

The curves in the image below have been projected onto the face using the 'Body.ProjectCurve' method. In the geometry settings I have 'Fine' detail enabled, with normal tolerance = 0.10, surface tolerance = 0.10, curve tolerance 0.10 for maximum accuracy.

The 'Wire.GetGlobalCurveIntersections' method does not find any intersections between the curves.


Close examination (below) reveals that the lines do not intersect due to the graphical approximation of the curves as straight line segments.



I thought it would be possible to find approximations to the intersections using the position 'out' parameters of the 'CollisionDetector.MinimumDistance' method, but I get a 'COMException was unhandled' error.

Can anyone suggest solutions to these problems?

Thanks,

Kevin

Niklas Skoglund

Hi Kevin,

 

the Geometry system in RobotStudio does not use the graphichal representation (mesh) of bodies for calculations, so the level of details should not affect the result of geometric operations.

 

Collision detection does not use the geometric representation, but the graphical (mesh).

 

Can you please send me a Pack&Go, and I will try to reproduce the problem?

Kevin

Hi Niklas,

I no longer have my original files so I have recreated a demonstration of the problem.

A plane grid is projected onto the curved surface of a block (which is an imported .sat file created in Autodesk Inventor).
The intersections of the projected lines are then found and displayed.
Each line should have 5 intersections, but you will see that many are missing.

I have also experimented with a simple block with a curved top face, created in RS by intersecting a cylinder with a box. In this case the intersections are all found as expected.

Are there are some special settings required when creating a .sat model?

The .zip file includes a Pack&Go, the C# project and the .sat file.

Regards,

Kevin

webwiz/40/CurveIntersectionProblem.zip

Niklas Skoglund

Hi again,

 

I've tried your AddIn and can reproduce the problem.

I also tried to create a box with the same size as your part, and ran the Add-In.

In this case it worked well, as you said.

 

Also checked if it can have something to do with body location with respect to the part or something like that. Same result though.

 

Maybe there is a problem with the geometry after all.

Do you have the possibility to import the .sat file into another CAD system and see if it complains about the health of the model?

 

How did you create the .sat file?

 

I'll continue debuggin, just wanted to give some feedback.

Kevin

Hi Niklas,

The .sat file imports into Mastercam without any problems.
The model was created using NGC and SolidWorks, not Inventor as I stated previously.
The following method was used:

Curves created in NCG were imported to SolidWorks, then lofted to form the top surface. A rectangular box was then extruded from below to meet the surface. The sides and one end of the block were then cut at angles with planes. The other curved end was cut with a random spline. The model was saved as a V13 .sat file.

Thanks & Best Regards,

Kevin