[Arno.Klocke_Estia]

Hello, 
First of all thank you so much for the RoboDK software it's the best OLP software I have ever tried ! 
I am working on a project that aims to weld bicycle frames in France. 
I am having trouble with finding all the right parameters for Curve follow project and external axis optimization, but I think I have found the right proportion for the welding path I want to achieve. 
My problem comes from the avoid collision algorithm for which there is a +-180 degrees on the Z axis of the tool. 
You will find attached the RDK file with the cell.

The first CFP which does exactly what I need, great algorith with the weight by the way very intuitive !
The second CFP which should avoir collisions turning the tool +-180 degrees and doesnt converge to a solution. 

The third is a manual program I did using joints target from the first CFP programm and manually adjusting the orientation of the torch on the last points to avoid collision. 

Is there something I have done wrong in the parameters ? Did I not understand what avoid collisions does ? Is there a better way to achieve the result from the 3rd program ? 
I would love to have your insights and advice on this problematic ! 
Thank you so much 
Arno Klocke

[Albert]

Thank you for your feedback! We are glad you like RoboDK for simulation and the weighting approach for optimization. I'm sorry we took so long to get back to you.

I noticed you activated the collision checking option. This will avoid collisions by rotating the tool around the Z axis of the TCP. By the way, this option is somehow hidden as it takes reasonable resources to check this against collisions but you can enable by selecting Tools-Options and checking the option Allow automatic collision avoidance.

The project you mentioned (CFP_collision) is a bit challenging to solve if you want RoboDK to automatically avoid collisions with a curve follow project because the tool has quite a vertical shape and rotating around the tool Z axis does not have that much of an impact. Furthermore, the tool can only rotate in one direction because in the other direction it has a singularity (axis 5 at zero), so the tool becomes stuck at the point where it notices there is a collision. Also, moving 20 deg in one step may be a big movement in production when you are so close to a wrist singularity (J5 close to zero) so ideally you should set smaller steps for checking.

In your case the weld curve is short and I would recommend you to maintain a constant rotation around the Tool Z axis. To make your path work I followed these steps:

1. I noticed that rotating the tool by 60 deg around the Z axis at the last point would make the path collision-free, so I applied this offset on the Path too tool offset.
   
2. I blocked any potential Z rotation by the algorithm setting the Allowed Z rotation to zero. The rest of the settings should not alter what happens between the tool and the part.
   
3. In the Axes optimization option I added some weight to try to maintain the Joint 5 at 26 deg (approx), which helps keep it away from the wrist singularity (Joint 5 close to zero).
   

Without any further edits the project can be quickly resolved.

You have a nice cell by the way!