Absolute accuracy parameters

Vlad222

Hi all,

I have absolute accuracy robots and I need to calculate forward kinematics by myself because we are using our software for building trajectories. Robot has parameters like error_offset_z, error_roll, etc. for each link.

But I don't know coordinate systems for robot links. I get DH modified parameters from RobotStudio PIM.xml for building coordinate systems. I draw CS for 4 links and understand that errors not in these coordinate systems.
I also tried to use equal CS (z - up, x - forward) for all links but it also is wrong.

Can you help me to understand which coordinate systems are used for each link correction: rob1_1, ..., rob1_6?

jbeck28

Hi Vlad,

I'm working on the same problem. I'm wondering if you ever made any progress on this? I've reached out to ABB customer support and have yet to hear back. I'll probably update this if/when I hear back from them.

matti

Hallo, so far as I know, what ABB uses as DH-Parameters is based on  method of John J Craig.

See here for roll/pitch/yaw.

https://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=&ved=2ahUKEwj7s4XSmbH-AhW47LsIHbTXBGQQFnoECBoQAQ&url=https://mycourses.aalto.fi/mod/resource/view.php?id=607620&usg=AOvVaw3nV0ajAZXhgMV33G0HTjo1

An offset is a deviation of the arm-length.

I don't what compliance is in that case.

angeloc

Hi, any news on this ? 

I did take a look to the DH parameters using J. Craig method, but I can't figure a clear way to apply the offsets to that parameters. Somebody has some experience with this ?

Best, Angelo

matti

Hallo, so far as I know, the absoulte accuracy parameters are added at the controller, when moving linear or joint (not abs). AbsAcc is used to compensate the difference between the ideal robot model to the real mechanical arm, which might be different on every robot. So when planning in RSO you use always the ideal model and it is no use of calculating AbsAcc in advance (?)