hi

i made a vismach model... i update it to the home position i want.. its 1:1 after homing th real arm.

 

i dont know if it helps but if i home in this position. x0y0z0a0.5b0c0 in Identity/Joint Mode

 

and in the world mode

 

but if i jog in world mode  x + - i see the real failure on the vismach model..

 

same in Y

 

i dont know if this explain some wrong dh parameters?! but in some positions the A axis.. joint 4 on the arm starts flipping

thanks

Man page Description :
The spindle is assumed to have stopped in an arbitrary position. The spindle encoder position is linked to the position pin. The current value of the position pin is sampled on a positive edge on the enable pin, and command is computed and set as follows: floor(number of full spindle revolutions in the position sampled on positive edge) plus angle/360 (the fractional revolution) +1/-1/0 depending on mode.

Do i understand that with mode 0 offset is 1, with mode 1 offset is -1, with mode 2 offset is 0 ? because during tests i seemed to find these shifts.

I think this shows the basics of the summed PIDs.
 

Thank you guys for your replays.

To  cmorley
I am using LinuxCNC 2.9.10
 

I've not used M19 but it looks like the orient component does not use index at all.
 
Though M19 does use index:

"Spindle orientation requires a quadrature encoder with an index to sense the spindle shaft position and direction of rotation."

So I would expect spindle.0.index-enable to be set true at some point.

I would have thought that with "Raspberry PI with GPIO" you would have already had your cheap low-cost HW assisted engine.  If you must use a PC and don't want to find one with a parallel port, low-end Mesa cards are my suggestion (like the 7i92TH or 7i96S).  I think with Remora you'd "get what you paid for" and eventually a low-end Mesa card would be a better bargain, and much more turn-key and supported.
 

Thanks for your response. I realize that an old PC with parallel port works. Counting on an old PC going forward is not something that appeals to me. I also understand that the Mesa card is solid but the price is less than desirable. Noting that I am not an expert, it seems that the Remora with RP2040 over ethernet should be up to the job and be far cheaper than the Mesa cards. Unfortunately,, I don't have the skills to write the SW so the question remains: Is/or will be Remora with RP2040 ready for prime time? Note: currently I have the Raspberry Pi 5 running Linuxcnc using its GPIO port (buffered with some simple buffer HW but not aux processor) and it will probably meet my needs. That said, a solution based on a cheap aux processor would be a big benefit.

ok the first pose is what i wish... arm is on the right side from the " tower" this means there is a -Y correct.

i played a little bit arround...

what i found: some failures are "softlimit positiv reached 500" i open the min max limits to 750 - 750... still for play more arround. after this message i get position error... but ich can manual jog in jooint mode many more deg. and all speeds are slow!

you wrote :

Lets verify your home pose:

1. Home the arm
2. Activate 'Identity' mode
3. Remove all offsets (MDI: g10 l2 p0 x0 y0 z0 a0 b0 c0)
4. Move all joints except joint_4 to zero (MDI: g0 x0 y0 z0 a0 b0 c0)
5. Take a screenshot of the axis gui window
6. Take a picture from the side (ie the Y direction) of your robot
7. Post the two images


i do the g00 x0y0z0 a0b0c0.. but correct would be without a0?

i have really issues with the right hand rule and rotate and flip the coordinatesystem.. i must build something with toothpicks and a cheese cube.. ...


homeing : i need on joint 4 or 5 ( joints here not linuxcnc.. i men robot) a 1deg. offset..if i dont have it.. kinematic errors came after homing... like in the example.. but with the puma560 genser simulator.. i can rebuild the existing failures....


if i throw in the ini the line in:
RS274NGC_STARTUP_CODE = G21 G10L2P0 x19.2 y5.5 z9.4 a90 b0 c90 (debug, ini: startup offsets1 set)

this line is from the gesner kins puma 560 example
it works better on my real puma

Mars wrote:

Not old PC desktop based
Low cost hardware
Are you thinking something like an SBC (single board computer)?

windows parallel I/O
can you explain, do you refer to gui in general, or Microsoft Windows (LinuxCNC has no current association with Microsoft).

Sounds like an interesting project, just trying to understand what you ask for.

My goal:  a X/Y Linuxcnc based system with slow movement speeds (open loop steppers).  The constraints:
* Not old PC desk top based or some kind of windows parallel I/O
* It consists of a cpu running Linuxcnc with a dedicated processor doing the step/pulse interface to stepper drivers
* I think this is pointed at a Remora implementaion however I need something that is relatively stable and functional and *up to date* in terms of the HW.
* Is there  *up to date* documentation on how to install and use it.  I tried in the past to go with Remora and a 3d printer card only to find that the Remora documentation was seriously out of date and I wound up with a dead end.
* I have asked on the Remora part of the forum if the RP2040 based system (which sounds great!) is ready for prime time and I have had no responses since posting it a couple of weeks ago.  Is the impression I am left with which is that it is not ready and the enthusiam for it has died out?  
* I understand the fun of developing and tweaking a solution but for someone who wants to use the system and is somewhat conversant in this subject, figuring out what to commit to is very difficult.  Is there a *real* guide for potential users?  Are people figuring out how to get something to work and not reporting back?  Or are people giving up and just buying the expensive solutions?  Am I completing missing something and my concerns are unfounded?

 

Thanks, it fits perfectly what I wanted to do!