Robotic kinematics

[YuriConfessor]

@JoergS5 I'm reading the discussion so I can know what kind of progress have already been made.

I've noticed that the robot viewer is not avaiable anymore, is there any specific reason for that?

[JoergS5]

@YuriConfessor said in Robotic kinematics:

robot viewer is not avaiable anymore, is there any specific reason for that?

The robot viewer was based on Denavit-Hartenberg, and I changed to screw theory. And second reason is, DWC is based on TypeScript now instead of JavaScript and I have not migrated yet. A third point is that I'd like to base all on C++ code. I'm still searching for a good solution to visualize. Qt (using C++) offers a web interface, which could be used in DWC, but unfortunately not in SBC mode (a Raspi connected to Duet).

[Toaster0042]

@JoergS5 Hi, has there been any updates on this? I am seeing that in the documentation the parameters are still D and H. Is it still in the released version of RRF or has it already been changed?

[JoergS5]

@Toaster0042 D is a documentation mistake, I'll check and remove the wrong parts. It's all based on screw parameters. In respect to axis definitions the C parameter.

[Toaster0042]

@JoergS5 I have tried using the 4 axis pelletized earlier and was unable, will you be releasing it soon? I am using this for a school project and tought it was working so I am in a bit of trouble now

[JoergS5]

@Toaster0042 I will make a release soon.

[JoergS5]

@Toaster0042 You can help me by providing

• some pictures of the robot arm. Special interest is how the parallelogram is built, i. e. is it a triangle or some other solution. How is the parallelogram connected to the endpoint?
• exact measures of arm lengths
• to which parts are the steppers connected

This allows me to build the same and verify the code before publishing.

[Toaster0042]

@JoergS5 I can get the measurements to you a bit later but this is the arm I am using https://www.instructables.com/Build-a-Giant-3D-Printed-Robot-Arm/

[JoergS5]

@Toaster0042 I don't need the measurements, because it's not a 4 axis parallel robot.

It's like an industrial 6 axis robot, but without the 6th axis. Instead the 6th axis, the 6th actuator is used to grip.

I have code for the 6 axis robot, but not for your 5 axis plus gripper. I have to think about it. Your project is interesting, I want to support your robot type if possible. I will ask you to test code with your robot to verify the code.

[Toaster0042]

@JoergS5 ah ok, I tought it would fall under the 4 axis robot with an aditional rotating joint, I am fine with testing it I simply need to finish printing it as I have not finished it yet and was trying to get the firmware set before but I will be happy to test the code

[JoergS5]

I have time in May and June now to proceed developing robot kinematics. The order is

• 4 axis parallel (the black robot arm), probably as a quick-and-dirty approach first for @YuriConfessor
• DWC plugin to design and analyse a given model
• CoreXY/Prusa/Cartesian 5 axis AC and BC
• 6 axis robot
• testing whether Qt is a possibility for a designer/slicer
• elaborate tool design. My personal priority is using robot for CNC, so I'll work on support for different tools (tool shape etc).

I'll use 3.5.1 as basis.

[Mummed]

@JoergS5 Dear Joerg, thank you for sharing all of your hard work. I have this post and RepRap configuration regarding robot 3D printing. Since I am new to this topic, I may as you s question about configuring. Can we use the same procedure if we have a 6DOF robotic arm with its own controller and need to add an extruder to it?
from my understanding, most of the discussions in the forum and documentation focused on developing a robotic arm and its configuration however I couldn't figure it out how to synchronize robot motion and extruder commands for printing.

Thank you,
Mohamad

[o_lampe]

@Mummed You can define fans, heater and a tool same as any other 3D printer. But to make it work with a 6DOF arm, you'd need a matching slicer.

[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.