[chbot] Simple robot programming

Richard Jones rjtp at ihug.co.nz
Wed Jul 1 09:01:03 BST 2009


A couple of other perspectives on lowering the bar of entry to robotics:

1. Simple howto's such as this one on AVR:
http://www.tuxgraphics.org/electronics/200411/article352.shtml
There's no rocket science in there, but everything is gathered in one place
with a nice progression to a low cost open ended platform that does not
have the limitations of simplified approaches.

2. I have a sneaky feeling that if you could join scratch to a robot you
could get 6 year olds moving robots around in no time:
http://scratch.mit.edu/ 

Richard

On Wed, 1 Jul 2009 18:39:33 +1200, jimmy allen <jimmy1248 at gmail.com> wrote:
> you could use flow charting or structure diagraming
> this is how my programaming teacher gets us to plan our code and it
> gives a visual feel for how a program is going to work
> 
> On 7/1/09, Morris <skibear at gmail.com> wrote:
>> Thanks for the summary and links!
>>
>> classicladder is interesting! Looks to be active and a lot more than a
>> simple ladder logic editor/executor.
>>
>>
>>> I don't know whether the execution engine is separated from the drawing
>>> tool. The web-page was last updated in 2009, so it might still be
>>> maintained.
>>
>>
>> "It can run on little embedded platforms (no GTK interface dependance,
>> and number objects to allocate for less memory usage)." strongly implies
>> that the execution engine can be used stand-alone. However I suspect it
>> would not be a trivial amount of work to get it to the point I could use
>> it for my own uses!
>>
>> Cheers
>>
>> On Wed, 2009-07-01 at 17:18 +1200, Stephen Irons wrote:
>>
>>> A PLC is just a robot used to control industrial machinery, and PLCs
can
>>> do a wide variety of tasks. IEC 61131-3 specifies five languages for
>>> programming PLCs: Ladder Diagram (LD), Instruction List (IL),
Structured
>>> Text (ST), Function Block Diagram (FB) and Sequential Function Chart
>>> (SFC). IL is exactly the same as LD, except using text notation rather
>>> than diagrams. ST is a Pascal-like programming language and adds
nothing
>>> that any other imperative language can provide, and is probably not as
>>> well-defined as modern languages.. FB adds the ability to incorporates
>>> nested blocks of the other languages, and is very useful. SFC adds
>>> state-machine like behaviour.
>>>
>>> The combination of LD, FB and SFC is very powerful.
>>>
>>> As Charles mentioned, there are at least three parts to the system: the
>>> drawing tool, the compiler and the execution engine. An
almost-essential
>>> additional part is a debugger.
>>>
>>> In a previous job, I ported a (commercial) PLC execution engine to run
>>> on a 2 MHz 68HC11, so a WRT-style router will certainly have the oomph
>>> to do it.
>>>
>>> The drawing tool, compiler and debugger were Windows-hosted.
>>>
>>> The drawing tool included support for all five IEC 61131-3 languages.
>>> The drawing tool also included software-engineering utilities such as
>>> version control, documentation generation, etc.
>>>
>>> The compiler generated byte-codes that were loaded into the target and
>>> run.
>>>
>>> The debugger connected via any available channel (of course, you had to
>>> port the communication code), and you monitor the states of inputs,
>>> outputs and variables, could set breakpoints and watchpoints in all
>>> sorts of ways.
>>>
>>> The execution engine was very standard ANSI C, so could be ported to
>>> just about anything.
>>>
>>> The name of the system was IsaGraf, and they are still around. The
whole
>>> system cost a lot, but was far cheaper to buy than to develop
ourselves.
>>>
>>> As far as I know, there are no Linux-hosted tools that do all of this.
>>> However, there are a number of places to look:
>>>
>>> http://membres.lycos.fr/mavati/classicladder/ includes LD and SFC. I
>>> don't know whether the execution engine is separated from the drawing
>>> tool. The web-page was last updated in 2009, so it might still be
>>> maintained.
>>>
>>> http://mat.sourceforge.net/ looks interesting, but they don't seem to
be
>>> very active: last updated 2006.
>>>
>>> Stephen Irons
>>>
>>>
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