creating link between Robot axes

[Robmaksan]

Hi All,

I am trying to do a robot simulation. I want to import the step files of robot axes (ABB supports this), then link axes with each other. I had no problem importing parts, but I have no idea how to link them and simulate a point. Could you share some progress path, opinion, or example? I really appreciate any help you can provide.

Regards
Murat

 

[DanB]

I'm not exactly sure what you mean by "robot simulation" and "simulate a point"?

Assuming that you want to use Open Cascade for robot planning, or some form of digital twin - my experience is that Open Cascade is very capable. gp_Trsf class for joint transformation is easy and intuitive, and XDE allows you to load links from assemblies into separate controllable objects.

Are you aware of Forward/Inverse kinematics and Denavit-Hartenberg conventions?

Robot kinematics - Wikipedia

en.wikipedia.org

Denavit–Hartenberg parameters - Wikipedia

en.wikipedia.org

 

[Robmaksan]

Hi DanB, Thank you for your answer.

Yes, you are right. I am trying to do Robot planning, and also I am aware of Forward and Inverse kinematic. But I don't know how to link (connect) axes to each other. I mean, when I rotate axes 3, axes 4,5,6 should move together. Could you share an example?

 

[DanB]

What you are asking for is forward kinematics. If all axis is set correctly by Denavit-Hartenberg, you could do something like this for FK:

baseTrsf.SetRotation(gp_Ax1(gp_Pnt(0, 0, 0), gp_Dir(1, 0, 0)), 0);
link1Trsf.SetRotation(gp_Ax1(gp_Pnt(0, 10, 0), gp_Dir(0, 1, 0)), j1 );
link2Trsf.SetRotation(gp_Ax1(gp_Pnt(0, d1, 0), gp_Dir(0, 0, 1)), j2 + PI / 2.);
link3Trsf.SetRotation(gp_Ax1(gp_Pnt(0, d2, 0), gp_Dir(0, 0, 1)), j3 );
link4Trsf.SetRotation(gp_Ax1(gp_Pnt(0, d3, 0), gp_Dir(0, 0, 1)), j4 + PI / 2. );
link5Trsf.SetRotation(gp_Ax1(gp_Pnt(0, d3, a4), gp_Dir(0, 1, 0)), j5 );
link6Trsf.SetRotation(gp_Ax1(gp_Pnt(0, d4, a4), gp_Dir(0, 0, 1)), j6 );

gp_Trsf newLoc1 = link1Trsf;
gp_Trsf newLoc2 = link1Trsf * link2Trsf;
gp_Trsf newLoc3 = link1Trsf * link2Trsf * link3Trsf;
gp_Trsf newLoc4 = link1Trsf * link2Trsf * link3Trsf * link4Trsf;
gp_Trsf newLoc5 = link1Trsf * link2Trsf * link3Trsf * link4Trsf * link5Trsf;
gp_Trsf newLoc6 = link1Trsf * link2Trsf * link3Trsf * link4Trsf * link5Trsf * link6Trsf;

Note that this solution is really not an elegant way to solve it, and values are arbitrary. The purpose is to demonstrate the principle.

 

[Robmaksan]

Dear DanB, Thank you so much for your answer. You solved my problem. I tried it works well. I appreciated