I'v put this on a new thread so it can be easier to find.

Originating thread:
https://groups.google.com/forum/m/#!topic/machinekit/oxctaPp4n8Q

> On 21 Apr 2018, at 18:21, sliptonic <[email protected]> wrote:
> 
> 
>> On Friday, April 20, 2018 at 4:19:36 PM UTC-5, Bas de Bruijn wrote:
>> 
>> 
>> What do you want to know? It's pretty hard to write something a la "Here's 
>> everything i know".
>> 
>> Do you have a (Preferrably non CNC) project in mind? 
> 
> A couple years ago I bought a scara bot just to play with.  No serious plans, 
> just a learning platform for things like ROS, FreeCAD robot workbench and 
> machinekit on a deeper level.
> I can now control it like a CNC machine but that's not what I want.  Maybe I 
> want to do something silly like sort coins or pick out blue legos.  

Yeah, that Lego sorting problem I know. I've helped with that a few times, but 
after 2 months all is mixed again and they "can't find" the pieces anymore.

> I understand conceptually how ROS works but ROS learning curve is a bitch so 
> getting from concept to actually controlling the robot is going to be a 
> process. 

Yes it is.

> Now that I can control it in Machinekit like a CNC, how do I start connecting 
> it to ROS?

The stuff I did a few years ago was creating a node which listens to a ROS 
joint_path_command topic, jointtrajectory message. These segments (point1 
time1, point2 time2, etc) are put in a HAL ringbuffer.

Then on the HAL side, the ringbuffer samples are read, and interpolated. Which 
results in a position-cmd per HAL cycle (1ms for example)

So in a nutshell: ROS does planning in non-RT and Machinekit Hal does the 
playout.

Mind: you still have to take care of initializing your hardware, homing joints 
etc. ROS doesn't do that. Also creating you robot model urdf and making moveit 
configurations for that.

> What's realistically possible with the current state of machinekit? 

Short now: interpolate segments in HAL and use the values further on, with 
whatever HAL logic/setup you come up with

Later: HAL as a ros_control resource.

> My questions are probably newbie which is why I was looking for blogs and 
> examples to study.

Apart from the ROS learning curve,
I think that the big issue is that the legacy cnc documentation is irrelevant 
for setups that do not use CNC.
Also, the focus has not been on HAL.

Before I even think of writing stuff i'd like to know what you all want to 
know. There's been a lot of effort put into making the documentation easier to 
work with, but that does not mitigate the outdated content.

So updating HAL focused content: what questions would you like to have answered 
that are not here:
http://www.machinekit.io/docs/index-HAL/

Then I'll try to come up with some tutorial/steps which we can all discuss. And 
if the outcome is something sensible I'll put that to the docs.

> Here's a link to my blog with a video I made a couple weeks ago:   
> http://sliptonic.com/lenny-the-big-dumb-bot/ 

That's a nice sturdy looking robot!

> Sorry OP,  I didn't mean to hijack this thread.  Feel free to split it out or 
> I'll start a new thread.

-- 
website: http://www.machinekit.io blog: http://blog.machinekit.io github: 
https://github.com/machinekit
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