Triperon Motion

[oliof]

@speedpete there are two different kinds of Tripterons:

1. Orthogonal Tripterons in a box frame -- These use Cartesian kinematics and can be run without any changes to firmware. You could use the RepRapFirmware configurator to create a config.g for these.

2. Colinear Tripterons in a delta frame like @Apsu s delteron -- these use their own kinematics as implemented in my fork and need firmware changes. I'll need to check whether it can be done as @dc42 says, but back in the day I couldn't make it work (but that's probably my lack of understanding and not a limitation of the firmware).

[oliof]

@dc42 these are the inverse kinematics for colinear tripteron

/*
Inverse Kinematics
     *
     * 3x3 reduction coefficient matrix * 1x3 coordinate matrix
     * [a_x -a_y 1]   [x]
     * [b_x -b_y 1] * [y]
     * [g_x -g_y 1]   [z]
     */

How'd that be expressed in M669?

But besides that I needed arm angle and the height at which the machine homed plus some correction factor (which thinking about it today might be dropped in favor of adjusting steps/mm...) for proper movement, as well as delta style homing at the top (because the motors move the arms colinearly and not in a Cartesian fashion). I may pull out my prototype and do some testing; I assume I can drop a lot of my code if M669 matrix definition works.

[speedpete]

@oliof
That would be very interesting ...nice of you Truly I really depend on you in this case ...so please give it a try

Best Regards
Peter

[dc42]

@oliof said in Triperon Motion:

Inverse Kinematics
     *
     * 3x3 reduction coefficient matrix * 1x3 coordinate matrix
     * [a_x -a_y 1]   [x]
     * [b_x -b_y 1] * [y]
     * [g_x -g_y 1]   [z]
     */

How'd that be expressed in M669?

If a_x, a_y etc. are constants, then this:

M669 K0 Xa_x:b_x:c_x Y-a_y:-b_y:-g_y Z1:1:1

with appropriate substitutions for a_x etc.

[speedpete]

@dc42
so a / b / g is a substitute for the lenght of the arms? ..and I have to find "a matching value" ?

Best Regards
Peter

[dc42]

@speedpete I have a feeling that a_x etc. are not constants but are trigonometric functions. @oliof, can you point me to your reference for the inverse kinematics?

[oliof]

@dc42 they are constants, see https://github.com/oliof/RepRapFirmware/blob/colinear-tripteron/src/Movement/Kinematics/ColinearTripteronKinematics.cpp

(sorry I haven't looked at this code in a long time, I am a bit confused).

[oliof]

I've now refreshed my memory and with some helpful explanations from @Apsu yes those are all constants.

[speedpete]

@oliof and @dc42
...and what does an example "mechanics alike Apsu" in G-code look like for my starting point?

Best Regards
Peter

[oliof]

@speedpete Grab the formula from my code to compute the constants and then set up the kinematics as @dc42 described. I didn't get around to trying this weekend; I may be able to do this tonight.

[speedpete]

@oliof
I don´t know how to do this, I´ll wait for your try

Best Regards
Peter