Trajectory Planning, Look Ahead, Interpolation, NURBS

Hello List

Thinking about our casual Orocos project again...

Today I've been looking around the internet once again for any open source NC kernels. There seems to be just nothing.

Our plan is to equip a CNC gantry style (3-5 Axis) waterjet machine tool with ethernet fieldbus drives/IO and an industrial PC with Linux/Xenomai/Orocos RTT. With this setup we try to proove us the feasability of a largely opensource based, really open and component based CNC control.

Our biggest concern is the NC kernel. Of course there are many papers around and we even used to build our own (2.5DOF) CNC control so far. It's not opensource though and not (yet) multi axis capable.

Now the actual question: What do you guys use to do the trajectory planning, cutter compensation, look ahead, acc/decc/velocity profiles, toolpath interpolation? These are standard robotics/nc problems and probably many projects using
Orocos need a solution for these things. Is anybody using NURBS for these things? Is there actual opensource code around?

So far we are using Orocos RTT as the component framework and KDL for inverse kinematics. These are great and it is nice to work with it. Does anybody use a closed source NC kernel like eg. ISG with Orocos? Are there actually any machine tool builders using Orocos in their CNC controllers yet?

Hmmm... still many open questions in our little project. Hope to get some of them resolved with your help.

Thanks for reading

Marc

Trajectory Planning, Look Ahead, Interpolation, NURBS

On Thu, 16 Jul 2009, marc [dot] bodmer [..] ... wrote:

> Thinking about our casual Orocos project again...
>
> Today I've been looking around the internet once again for any open
> source NC kernels. There seems to be just nothing.
>
> Our plan is to equip a CNC gantry style (3-5 Axis) waterjet machine tool
> with ethernet fieldbus drives/IO and an industrial PC with
> Linux/Xenomai/Orocos RTT. With this setup we try to proove us the
> feasability of a largely opensource based, really open and component
> based CNC control.
>
> Our biggest concern is the NC kernel. Of course there are many papers
> around and we even used to build our own (2.5DOF) CNC control so far.
> It's not opensource though and not (yet) multi axis capable.

We have used the NIST open source C library for such purposes in the past:
"The NIST RS274NGC Interpreter - Version 3"
<http://www.isd.mel.nist.gov/personnel/kramer/pubs/RS274NGC_3.web/RS274NGC_3TOC.html>
(I don't find the link to the C library anymore... )
Here is a movie that students made, integrating Blender and Orocos:
<http://www.orocos.org/node/783>
Their website points to a zip file with some code:
<http://www.wikidate.net/images/e/e5/SAI.zip>.
The EMC2 project started from the same code, but extended it, and tightly
integrated it into EMC; too tight to get it out easily, I think.

> Now the actual question: What do you guys use to do the trajectory
> planning, cutter compensation, look ahead, acc/decc/velocity profiles,
> toolpath interpolation? These are standard robotics/nc problems and
> probably many projects using Orocos need a solution for these things.
> Is anybody using NURBS for these
> things? Is there actual opensource code around?

KDL has support for up to trapezoidal acceleration profiles. But motion
planning is not directly into the scope of the Orocos project... Basically
because: (i) none of the current users is highly into that, and (ii) we
mostly have enough with instantaneous motion specification and control,
based on sensor information.

> So far we are using Orocos RTT as the component framework and KDL for
> inverse kinematics. These are great and it is nice to work with it. Does
> anybody use a closed source NC kernel like eg. ISG with Orocos? Are there
> actually any machine tool builders using Orocos in their CNC controllers
> yet?

At least in some prototypes, but I don't know the details...

> Hmmm... still many open questions in our little project. Hope to get some
> of them resolved with your help.

I hope some useful things could be started from your efforts...

Best regards,

Herman
>
> Thanks for reading
>
> Marc
>

Trajectory Planning, Look Ahead, Interpolation, NURBS

A Dijous 16 Juliol 2009, marc [dot] bodmer [..] ... va escriure:
> Hello List
>
> Thinking about our casual Orocos project again...
>
> Today I've been looking around the internet once again for any open source
> NC kernels. There seems to be just nothing.

Just a moment,

have you seen?

http://www.linuxcnc.org/

http://wiki.linuxcnc.org/cgi-bin/emcinfo.pl

> Our plan is to equip a CNC gantry style (3-5 Axis) waterjet machine tool
> with ethernet fieldbus drives/IO and an industrial PC with
> Linux/Xenomai/Orocos RTT. With this setup we try to proove us the
> feasability of a largely opensource based, really open and component based
> CNC control.

good.

> Our biggest concern is the NC kernel. Of course there are many papers
> around and we even used to build our own (2.5DOF) CNC control so far. It's
> not opensource though and not (yet) multi axis capable.

look emc ..

regards....

Trajectory Planning, Look Ahead, Interpolation, NURBS

Hi, thanks for your reply

Yes, I know EMC (personally use it at home).
It is really a great software, but it has it's limits:
- not components based
- 8 Axis limit (we need 20 finally)

Trajectory Planning, Look Ahead, Interpolation, NURBS

A Dijous 16 Juliol 2009, marc [dot] bodmer [..] ... va escriure:
> Hi, thanks for your reply
>
> Yes, I know EMC (personally use it at home).

ok

> It is really a great software, but it has it's limits:
> - not components based
> - 8 Axis limit (we need 20 finally)

you were talking about ...

> Our plan is to equip a CNC gantry style (3-5 Axis) waterjet

>Our biggest concern is the NC kernel. Of course there are many papers around
and we even used to build our own (2.5DOF) CNC control so far.

2.5DOF meas 25DOF now 20DOF?

Trajectory Planning, Look Ahead, Interpolation, NURBS

A Dijous 16 Juliol 2009, marc [dot] bodmer [..] ... va escriure:
> Hi, thanks for your reply
>
> Yes, I know EMC (personally use it at home).
> It is really a great software, but it has it's limits:
> - not components based
> - 8 Axis limit (we need 20 finally)

you were talking ...

> Our plan is to equip a CNC gantry style (3-5 Axis) waterjet ...

> Our biggest concern is the NC kernel. Of course there are many papers around
and we even used to build our own (2.5DOF)

2.5DOF -> 25DOF? -> 20DOF???

Trajectory Planning, Look Ahead, Interpolation, NURBS

Well, in our current CNC we have XY interpolated and an additional Z Axis, the machine has a gantry and 4 independent cutting heads = 2.5 DOF and 10 Joints.
With our new CNC we are heading towards 5 DOF with respectively 18 joints (OK, not 20...). EMC supports 6DOF with 8joints, when I am correctly informed. Anyway, we want a component based approach and be able to have our own parameter system, interpreter, GUI and some other specific functions. With EMC it would still be a lot of work too, so we'd prefer to have our own architecture with an Orocos based system.

Sorry if I was not clear enough in my first post.
Thanks anyway, EMC is surely a candidate one should consider if one needs a CNC.

Marc