Lobster

Information

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

Members: 70
Latest Activity: on Sunday

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

videos

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

Started by Daniel Piker Jul 17, 2011.

View All

Comment Wall

Comment

You need to be a member of Lobster to add comments!

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 rljohns 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.

Comment by Philipp on July 23, 2011 at 6:35am: Daniel, But cant we just make a 3d-matrix of parameters for each servo for each point in 3d with a "resolution" (using galapagos and, maybe, pretty much time, but once) and then just make an algorithm of chousing optimal position (as far as there will be several positions for some of the points) and then interpolate values as we interpolate vector in vector field. It looks like a not-so-complicated algorithm... (from my newbie-in-scripting point of view)

Comment by Chris Mealing on July 22, 2011 at 10:56pm: Fantastic, and inspiring. I've built a version as well... certainly cruder, but a very interesting challenge [My version]. The concept of linking Rhino objects to the GH definition to represent the robot itself was very clever.

Thanks