Robotic kinematics

[Toaster0042]

@JoergS5 Hey! I just wanted to check back on this and see if you had made progress on this and if you had made the implementation of the new kinematics

[JoergS5]

@Toaster0042 you're right, I should inform, I will prepare an update.

[JoergS5]

I'm back with robotics. My partner passed away, I had to mourn, I have a new partner now since a few months, she will be on vacancy alone mid to end may. So this will be the time frame when I will work on robot kinematics again, based on RRF 3.6.

I will implement an idea I had last year and started implementing some time ago. Robotics solutions are be very different for forward and inverse kinematics. So I thought about a generic approach:

• a forward chain to combine different drive movements into one movement chain, with one or multiple solutions
• a backward (inverse) chain with the result of none to multiple solutions
• forward and backward chains are stored in arrays which can be set by parameters with M669. Kinematic code will simply process the chains
• to find the chain solutions, the user can think it through mathematically and set the parameters or he can use the to-be-programmed Qt based program to set solutions or simulate them and compare to measurements of the prototype
• the chain elements are code fragements to implement mathematical solutions. The mathematicsal solutions can be augmented in future releases when necessary

That's my plan.

[droftarts]

@JoergS5 I'm sorry for your loss. I'm glad that you have been able to move forward and find a new relationship, and I look forward to more robotics development. I really must rebuild my robot arm...

Ian

[jay_s_uk]

@droftarts Looking forward to seeing pictures of you with your robot arm fitted...

[o_lampe]

@jay_s_uk Hmmm,

[T3P3Tony]

@JoergS5 very sorry for your loss.

Thanks for the update on what you are planning.

[droftarts]

@o_lampe said in Robotic kinematics:

@jay_s_uk Hmmm,

My Bucky cosplay is at 1%.

Ian

[droftarts]

@JoergS5 Might this be useful in developing the reverse kinematics? https://hackaday.com/2025/06/03/simulation-and-motion-planning-for-6dof-robotic-arm/ which leads to https://hackaday.io/project/197770-manipylator/log/240946-manipylator-part-2-simulation-motion-planning
Though I think you may have progressed beyond this level already? Perhaps good as a starter for others getting involved.

Ian

[JoergS5]

@droftarts thank you Ian for the link. This approach is through Jacobian calculations. I started with this approach, but it takes too long time to calculate in Duet, because it needs iterations. Iterations are really bad for the resticted calculation resources of Duet and the approach described has a serious limitation of multiple singularity situations. Worse, sometimes I had no solution for the iterations. I changed to direct mathematical calculations instead and found screw theory and geometric algebra better suited.

As you told, the article is of course very good, e. g. to motivate starting oneself with robotics.