[cotenicolas]

i'm trying to cut a hole into a part using a knife blade. The part is held into the robot arm and the blade fixed in space.

here is the part and cut section that I want to cut using the knife blade



Since this is a knife blade, the knife blade must rotate to be able to stay tangeant to the cut line . The blade must also have an angle of attack (alpha) around 70°



I've imported the curves using solidworks plugin, I've tried two scenarios : Scenario 1 where the normals of the cut line are parallel to the part surface



Using this, the knife rotates around the cut line, however the angle of attack of the blade (alpha) doesnt stay consistent throughout.

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Second senario, I selected the normals perpendicular to the part



The orientation of the blade along the cut line seems to be pretty good, however, it doesnt rotate to follow the path




How do I set the parameters so that the blade stays tangeant to the cut line, and has the right angle compared to the surface of the part?

[Jeremy]

Hi cotenicolas,

I've tried to replicate the situation on my side, but if you could transfer the station, that would help.

Jeremy

[cotenicolas]

Hi cotenicolas,

I've tried to replicate the situation on my side, but if you could transfer the station, that would help.

Jeremy

Here you go! hope this helps

[Jeremy]

Hi Nicolas,

Hope you are well.
We just released a new version of RoboDK.
这个新版本包括一个新功能叫做“罗bot holds object & follows path".
That should help you reach your goal.

I did a few tests with your station and you may need to do some adjustment to avoid wrist singularity or joint limits.
These adjustments may be as simple as modifying the position/angle of the cutting tool (at the moment it's aligned with axis-1, which make it prone to wrist singularity) or splitting the cutting path in two sections, therefore letting the robot reposition itself between the path segments (a good way to avoiding joint limits).
Also, you should set the "Allow a tool Z rotation of" around zero as, in this case, rotating around Z would influence the angle of attack of the cutting tool.

Let me know if it helps.
Have a great day.
Jeremy

[Albert]

Hi Nicolas,

As Jeremy mentioned, you should see the option "Robot holds object & follows path" with the latest version of RoboDK (updated today). This will allow you to use the scenario where the curve normals are normal to the surface and keep the orientation along the path.

It may not be straightforward to solve the path with the RDK file you provided but if you take a look, you'll see that joint 6 quickly hits the negative limit. To take advantage of the full range of motion for joint 6 you can set the start point an extra turn toward the positive limit of joint 6. See attached image and RDK project with a potential solution.

You may want to remove the rotation allowed around the Z axis (180 deg by default, I did not alter this setting). This could break your cutter.

Albert