CoppeliaSim forums

Posted: **11 Nov 2021, 08:24**

Hello,

I'm a beginner in V-REP and I have been trying to make a custom controller which is including force control and PD control in Cartesian coordinate

For the first step, applying joint PD control of UR5 was successful, so I tried to get Jacobian matrix. In my case, I need Jacobian matrix for every step to calculate (J^T)F.

I read some documents as below:
https://www.coppeliarobotics.com/helpFi ... ements.htm
https://www.coppeliarobotics.com/helpFi ... Plugin.htm
https://forum.coppeliarobotics.com/viewtopic.php?t=5487
, however, I met a problem

I used sim.getIKGroupMatrix after making dummies in IK mode, an error occurred such that
- IK group does not exist. (in function 'sim.getIkGroupMatrix')

I upload my file that I'm working on, and I want to get feedback to calculate Jacobian matrix. The problem was in 134 row in child script

https://drive.google.com/file/d/1kOtjgf ... sp=sharing

Thanks

Posted: **12 Nov 2021, 15:11**

Hello,

since CoppeliaSim V4.2.0, you should create IK tasks via the API: this is quite straightforward, and gives you much more flexibility, also allowing to debug problems faster. This means that all FK/IK related functionality now is handled via the kinematics plugin, which exports API functions under the simIK.* namespace. The mentioned page illustrates the approach with a simple example. You can find many more examples in the folder scenes/kinematics.

Cheers

Posted: **23 Mar 2023, 14:35**

inje wrote: ↑11 Nov 2021, 08:24 Hello,

I'm a beginner in V-REP and I have been trying to make a custom controller which is including force control and PD control in Cartesian coordinate

For the first step, applying joint PD control of UR5 was successful, so I tried to get Jacobian matrix. In my case, I need Jacobian matrix for every step to calculate (J^T)F.

I read some documents as below:
https://www.coppeliarobotics.com/helpFi ... ements.htm
https://www.coppeliarobotics.com/helpFi ... Plugin.htm
https://forum.coppeliarobotics.com/viewtopic.php?t=5487
, however, I met a problem

I used sim.getIKGroupMatrix after making dummies in IK mode, an error occurred such that
- IK group does not exist. (in function 'sim.getIkGroupMatrix')

I upload my file that I'm working on, and I want to get feedback to calculate Jacobian matrix. The problem was in 134 row in child script

https://drive.google.com/file/d/1kOtjgf ... sp=sharing

Thanks

Excuse me, have you solved this problem? How to get the Jacobian matrix of UR5 and DH parameters? Thanks in advance.

Posted: **18 Apr 2023, 06:52**

With CoppeliaSim V4.5, you can now directly display the Jacobian via [Menu bar --> Tools --> Visualize IK world]. The DH creator and extractor add-ons have also been improved.
But keep in mind, a same kinematic chain has an infinite different DH parameters possible, depending on how the joint locations/orientations was selected.

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Calculating Jacobian matrix

Calculating Jacobian matrix

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Re: Calculating Jacobian matrix