Defining mechanism in the MTD simulation file

[Anonymous]

Hello,

I need help in defining the links movement relations (Mechanism) for the irb 6400R robot while creating the MTD simulation file, since it has extra links and extra dependent movements, Can PowerMill Robot handle such relations?

I have followed the MTD user manual and how to create the simulation, but frankly it's hard since the combination of links is different.

I have gone more than half the way, the cylinder and the piston are moving great, the tail and rod are moving also great when the 3rd axis is moving, but when the 2nd axis is moving then their movement is not as it should be, could you please help me with this? or give me a hint? since that I spent a lot of time on trying to solve this.

Attached the MTD simulation file.

Looking forward for your reply,

Stephan

[Yogesh.Mohite]

Hi @Anonymous,

Welcome to Autodesk community forum.

I am not able to see any attachment to this topic, can you please double check that you attached MTD data. Also if possible send small video of problem you are facing. So that it will be easy for me to find and understand source of the problem as there are many axis in robot MTD.

[Anonymous]

Dear Yogesh,

Thank you for your reply, I don't know how I missed uploading the MTD file.

Kindly find attached the MTD file and a video file.

As you can see in the video, when I move Axis 3, the robot moves as it's supposed, but when moving Axis 2, here where I have the issue, the tail should not move, and the orientation of the arm should stay unchanged (not revolve).

Attached also a video showing the correct motion (#2).

I do hope you can help me with it,

Best regards,

Yazan

[richard.pedley · Accepted solution]

Hi Stephan,

There is probably nothing wrong with your mtd file.

The difference is that in robot studio axis 3 is being changed with axis 2 to keep the tool orientation the same. This is fairly common.

If you want to get this simulation in PowerMill robot, load the robot into PowerMill. Open the robot cell tab, Open the Robot Configuration form, go to the simulation page, in the bottom left hand corner of this page is a checkbox to "Simulate linked motion betweeen robot axes 2 and 3". Check that and try simulating again.

Hopefully that will solve the issue.

Cheers

Richard

[Anonymous]

Hi Richard,

Thank you so much for your help, it actually solved the issue of dependent motion.

Unfortunately, there is another issue that has appeared once the first one was solved, which is:

When moving Axis 2, the tail should not move, well, it does not until Axis 2 reached a certain angle then they start to move together in one direction, I thought a lot about it but did not get a clue about it, so I do wish you can help me with it.

Attached a video shown the problem.

One more (which you can also see in the video):

==> When I load the robot, it says there is a collision between Axis 2 and the tail, but when I put the CAD together it was very accurate, what would be the solution for this? could this be the reason of the main problem above?

Looking forward for your reply asap, since I'm so eager to get this to work.

Best regards,

Yazan

[richard.pedley]

Hi Yazan,

From what I can tell you have reached the limit of the tail's movement and PowerMill can't rotate axis 3 any further  without breaking the link mechanism, therefore it can only move axis 2 which you are driving, so it assumes you want to keep moving axis 2 but can't keep the relationship between axis 2 and 3. You can see this behaviour in my previous screen cast.

As for the collision this may occur when the models are triangulated. It is not something to worry about. If you add the below code to your mtd file (inserted between lines 18 and 19 in the collision_exclusion_list). This will clear the collision and these 2 components can not collide on the cell so there is no risk associated with ignoring collisions between them.

    <collision_exclusion_group>
      <collision_exclusion_part NAME="Tail" />
      <collision_exclusion_part NAME="RobotAxis2" />
    </collision_exclusion_group>

Hope that helps.

Richard

[Anonymous]

Thanks Richard for your reply, I was worry that I might be doing something wrong regarding the structure of MTD file, but anyways, is there a way to make modifications to the limits of the Tail or other parts so I achieve the simulation as in reality?

I'm attaching a video how it actually moves, its simulated in RobotStudio, I do hope you can help me with it, since no body else can help with this issue.

I highly appreciate your help,

Best regards,

Stephan

[richard.pedley · Accepted solution]

Hi Stephan,

No problem, unfortunately I think that is the limit of how accurate the jogging simulation gets. I'm not aware of a way to make it more true to the described movement. PowerMill simulation files aren't intended to be an exact replication of the motion of the robot when jogged, these are just convenience tools.

The simulation will be an accurate representation of how the robot will move during the programmed path and the dependent axes will collision check to ensure the path is collision free.

Sorry I can't give you the answer you want, but the mtd file will be more than good enough to get you up and running with the robot.

Cheers

Richard

[Anonymous]

Thanks a lot Richard,

I will move on with this simulation, but just to ensure I got you correctly, code output from the post processor when I try it on the robot itself, this issue of Tail limitation might not appear, correct? So the actual code is somehow independent from the simulation??

Best regards,

Stephan

[richard.pedley]

That is correct, the simulation is used to get the robot configuration data and check that the path will be free of issues but will drive the robot using cartesian coordinates. Joint angles will be calculated by the robot controller to reach that position and orientation.

Provided the CAD model is positioned in approximately the right place relative to the robot model the simulation will generate enough information to use the program on the robot.

Hope that helps.

Richard

[Anonymous]

Hello Richard

I am trying to simulate the Kawasaki ZX165U kinematics and unfortunately I'm stuck with the free / dependant axis that supports J2 and is also connected via upper block to J3. 

Attached is the overview of the robot STEP. Would you be able to share the MTD file that was used for your explanation video. This would definitely help in solving my issue.

Cheers!