Lobster

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Lobster is a tool for solving the inverse-kinematics of 6-axis robot arms

Members: 140
Latest Activity: Dec 7, 2023

Lobster_IK1.ghx

Lobster_IK1.3dm

Lobster_IK.pdf

This is still a work-in-progress, with plenty of room for improvement.

I've been meaning to release this for some time - I was intending to clean it up some more and maybe compile it into a proper component first, but have been too busy with other activities, and rather than delay any longer have decided to share it in its current state.

It is a purely geometric solution, specific to this particular joint configuration, which allows kinematic decoupling, greatly simplifying things. Luckily most commercial 6-axis arms follow this configuration.

Bear in mind the angle value outputs are not yet calibrated - one would need to check the direction and start angles to make sure they corresponded with the standard format. Also, joint angle limits are not included here, but could be fairly easily added.

The example model here is a Kuka KR-150, but it is designed so that one can easily swap the input model with other robots with the same joint configuration (6-axis with a spherical wrist).

I do also have a similar definition for robots such as the ones from Universal Robots which do not have a spherical wrist, but still have certain simplifying properties allowing a closed form solution:

I'll post the setup for this one too soon.

Lobster is distributed under the WTFPL license ;)

Use at your own risk. I accept no responsibility if you break your robot!

enjoy !

Discussion Forum

Lobster reloaded

Here's an update I've been meaning to post for a long while.As I'm currently at the RobArch conference in Michigan, now seems a good a time to finally get it out there.This is a very minimal scripted…Continue

Started by Daniel Piker May 18, 2014.

videos

Some videos from early tests: http://vimeo.com/22196011 http://vimeo.com/22519535 …Continue

Started by Daniel Piker Jul 17, 2011.

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Comment by Freddy on November 26, 2012 at 1:13pm: Hi,

I tried a sample file in KukaPRC and output the SRC to a KRC1 Robot:

Kuka PRC with KRC1 from Freddy Chang on Vimeo.

How do I output SRC from Lobster?

thanks,

Comment by Yusuf Buyruk on November 24, 2012 at 8:47am: Some components like Orient, Rotate are old. I have replaced with the newer ones.

Here are the links of the files.

Again! Use at your own risk. I accept no responsibility if you break your robot! :)

Lobster_IK1.3dm

Lobster_IK1.ghx

Comment by Daniel Piker on March 1, 2012 at 1:52pm: @Kenneth - neat! thanks for sharing

Comment by Kenneth cheung on March 1, 2012 at 8:42am: Thanks to Lobster Plugin, I made a fully lobster integrated script to move my home made robot arm.

http://www.grasshopper3d.com/video/home-made-robot-arm-iphone-contr...

&

http://www.grasshopper3d.com/video/description-of-grasshopper-scrip...

Comment by Freddy on January 29, 2012 at 6:33pm: I want to do this:

http://www.youtube.com/watch?v=UjMJOfCyDaA

Comment by Daniel Piker on January 29, 2012 at 11:04am: Hi Freddy,

Lobster certainly could be extended to work with 7 axis systems. Could you be a bit more specific about what stage you are at now, and how you are hoping it would work ?

Comment by Freddy on January 29, 2012 at 8:51am: Hello!!,

My external axis for my Kuka Robot is done, now the lobster software need to deal with, and GH.

Comment by H on September 18, 2011 at 2:09pm: Coming back to the general inverse kinematics problem, did you have the paper

L. Sciavicco and B. Siciliano. A solution algorithm to the inverse kinematic problem for redundant manipulators. IEEE J. Robot. Automat., 4(4): 403-410, 1988

in mind or what are your preferred methods?

What paper does use "cyclic coordinate descent"?

I'm a PhD student in automation engineering and robotics so working on a solution using Rhino + GH would be quite interesting.

Thanks,

Comment by Ryan Luke Johns on August 18, 2011 at 3:07pm: Daniel, thank you much for this great upload! How is the progress going with the UR-type definition?

Comment by Jeg on July 25, 2011 at 5:01am: hi Daniel, I've just added another video of Lobster simulating the forming of curved folds in sheet material.

Curved Folding Fabrication Simulation - using Kangaroo and Lobster ... from Jeg Dudley on Vimeo.