This is the theoretical explanation on general robot manipulators and how to use it for the advanced applications with UR robots. Attached the URScript sample is written for the purpose of better understanding. However, it has not been tested so that it is possible to have errors. Looking forward…

Great info! Wish other mfc’ters were this open… But why use the Jacobian to control the robot? Why not use the IK model? It’s analytical, precise and way faster… Regards, Max

@mvrooij This is actually not about the secret of UR control software. Rather, the document just explain about the general robot theory and how to utilize the theory for advanced applications with UR robots. Even if this document is written by a UR employee, only public documents are referred to. W…

@sba Ok, well, thanks for the information, it’s much appreciated and I welcome more information like this for the future.

I’ve since implemented the rotation matrix calculations so my code matches the UR teach pendant display. Much of the stuff in the document checks out nicely, however, for a certain set of motor angles I get a sign ambiguity in the calculated rx,ry & rz (exaclty inverted). Seems that UR uses an aditt…

In PolyScope we scale the rotation vector so that it looks more stable and doesn’t flicker so much. Below is the sample code regarding the scaling. from math import * v_init=[-0.0012, 3.1162, 0.03889] v=[-0.06, 0.13, -0.04] def length(v): return sqrt(pow(v[0],2)+pow(v[1],2)+pow(v[2],2)) def n…

There were errors in the previous version. I apologize for the late fix. robotics_r1.zip (3.1 KB) Robotics in UR Robots_March 2019_r1.pdf (1.5 MB)

Hello Max, the reason is that the Universal Robot has no central hand, meaning that the axis of the last three axis meet in one point. Without central hand, you cannot split the inverse kinematic problem into two sub problems (achieving orientation with axis 4, 5 and 6 as well as the position with…

Hello Jan, No, it’s not. There’s a perfectly fine analytical IK solution for the UR family of robots. I think the reason has to do with the way they calibrate the robots. Look at the calibration values in the robot. Those make it near impossible for the IK to be used, yet, are trivial to process in…

Robot theory and how to use it in UR robots

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mvrooij December 21, 2019, 8:29pm 7

@sba

Thank you. I’ve implemented the smoothing and it works fine now. It solved a real headache

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Robot theory and how to use it in UR robots

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