[chbot] Simple robot programming

Wed Jul 1 05:12:29 BST 2009

I am *really* into working out a simple way to program robots so hearing
about everyone's experience is grand.

> Morris: There are three parts to ladder logic programming:
> 1) The GUI engine where you draw the pictures. Sure that can be done
> over a web interface, but probably needs a relatively capable web
> server. Perhaps more than your WRT can handle.
> 2) Compiler: reduces the picture representation to executable byte
> code. Can likely fit on the WRT.
> 3) Interpreter. Tiny and can definitely exist on the WRT (well it has to :-).

Charles: A GUI could run very well on the router using
http://en.wikipedia.org/wiki/DHTML and
http://en.wikipedia.org/wiki/Ajax_(programming) - although an existing
implementation might not (IMHO any implementation not using a DHTML GUI
would suck anyway!!!) I am fairly sure about this because I do this sort
of web development for my day job (which is why I am not volunteering to
write it!!) If there is nothing practical that is available free for
Linux, then the whole idea of ladder logic is moot for me :)

Jimmy: I try to avoid microcontroller programming where possible because
it takes more time for less results. However, I would love to be shown
the flowchart programming interface. The platform I am using includes a
Linux OS running on the on the router (200MHz CPU, 16MB memory, 1GB
local storage USB stick) so there are other options for basic - I did a
quick search and found that http://www.blassic.org/ "classic basic"
installs on www.openwrt.org. I personally prefer the Python language
because it is a scripting language, has a great community, fantastic
tutorials, and excellent libraries (I love using solid code written by
other people whenever I can!). I have a vague wondering about whether
the Mono VM runs on the router - that way C# and VB could be used on the
router?! But Mono is not something I would consider for my own use since
I already have a solution that I like (I am not as keen on C#/VB or
compiled code :):)

On Wed, 2009-07-01 at 10:53 +1200, Charles Manning wrote:

> No single robot programming environment can cut it for everyone.
> 
> If you just want something that does very elementary things, like
> blink some lights when a switch is pressed, or a bump and turn robot,
> then ladder logic or the Lego Mindstorms style drag and drop
> programming can work well.
> 
> If you want to do anything more complex then you really need something
> a bit more meaty. Picaxe can take you to the next level, but soon
> reaches its limit.
> 
> If you want to go further than that: programming up reasonably complex
> behaviour, navigation, etc, then you do better with C, Java etc.
> 
> For instance, programming a GPS-based guidance system would be hell in
> ladder logic or Picaxe.
> 
> It is possible to make a fusion of different languages. For example, a
> C program and ladder logic program can share some variables so that
> ladder logic variables can then be processed in C then passed back to
> ladder logic.
> 
> Morris: There are three parts to ladder logic programming:
> 1) The GUI engine where you draw the pictures. Sure that can be done
> over a web interface, but probably needs a relatively capable web
> server. Perhaps more than your WRT can handle.
> 2) Compiler: reduces the picture representation to executable byte
> code. Can likely fit on the WRT.
> 3) Interpreter. Tiny and can definitely exist on the WRT (well it has to :-).
> 
> The web interface is perhaps where you want to end up, but I would
> suggest that it is far easier to start off by doing the drawing GUI,
> at least, on a host and sending down the byte codes.
> 
> On Tue, Jun 30, 2009 at 10:18 PM, jimmy allen<jimmy1248 at gmail.com> wrote:
> > i know that is why i moved on from them
> > by way are you a member on bright sparks because your name looks familiar
> >
> > On 6/30/09, timothy manning <tfhmanning at gmail.com> wrote:
> >> Hi Jimmy
> >>
> >> The problem with Picaxes is it's very limited and not expandable.
> >> It is also very expensive. If you want a BASIC lanuguage then use an
> >> AVR and run BASCOM on it.
> >> This way you can upgrade to C with out changing your controller board
> >> and it's very cheap compared to a Picaxe.
> >>
> >> -Timothy
> >>
> >>
> >>
> >> On Tue, Jun 30, 2009 at 5:43 PM, jimmy allen<jimmy1248 at gmail.com> wrote:
> >>> have any of you use picaxe system
> >>> it is good for beginners as you can write up programs using flow
> >>> charting or the basic language
> >>> you can write up fairly complex projects
> >>>
> >>>
> >>> On 6/30/09, Morris <skibear at gmail.com> wrote:
> >>>> I love ladder logic and had been thinking about it!
> >>>>
> >>>> Ladder logic is functional programming (which will make Paul Davey
> >>>> happy!).
> >>>>
> >>>> Ladder logic has an obvious DHTML web interface for it (that said I am
> >>>> not volunteering to do that because I do Ajax web development for my
> >>>> job :) but given how common it is I would hope there is something free
> >>>> out there already. I personally am attempting to avoid requiring
> >>>> anything installed on a PC, that way web-phones can be used for
> >>>> development and for remote control, and also so there is no dependency
> >>>> on having either Windows or Linux installed.
> >>>>
> >>>> Charles, I am very keen to hear what you find out - especially if it is
> >>>> web based open-source (Python would be perfect, but PHP, Ruby, Lua, Perl
> >>>> or Linux CGI apps can all be hosted on the wifi router web server -
> >>>> probably even DOS apps in DOSBox).
> >>>>
> >>>> Simon - is that a volunteer I hear! ;)
> >>>>
> >>>> Cheers
> >>>>
> >>>> Morris.
> >>>>
> >>>> On Tue, 2009-06-30 at 10:22 +1200, Simon Knopp wrote:
> >>>>
> >>>>> That project looks interesting. I agree, ladder logic is a good way to
> >>>>> get started with programming simple robots.
> >>>>>
> >>>>> What would really make a tool such as that powerful would be the
> >>>>> ability to create functional blocks, either of ladder logic or code. A
> >>>>> block of ladder logic would allow higher level commands like in
> >>>>> Mindstorms---"turn 90º left" or "move forward for 1 second". A block
> >>>>> of code (much like PLCs' structured text) could allow one to write a
> >>>>> function in C (for example) and have it represented as a block within
> >>>>> the ladder logic environment. These blocks could be created by anyone
> >>>>> who knows the language and distributed easily to those that don't.
> >>>>>
> >>>>> I know I'm sort of just describing what PLCs can already do, but to my
> >>>>> (relatively uninformed :-) mind it wouldn't be too difficult a feature
> >>>>> to implement into a system like that you linked to and would make more
> >>>>> powerful programming with ladder logic feasible and accessible to more
> >>>>> people.
> >>>>>
> >>>>> Just my two cents worth.
> >>>>> Simon.
> >>>>>
> >>>>>
> >>>>> On 29/06/2009, at 9:55 PM, Charles Manning wrote:
> >>>>>
> >>>>> > Morris and I had a very interesting conversation about simplifying
> >>>>> > robot programming.
> >>>>> >
> >>>>> > Many people are drawn to Mindstorms-like drag and drop programming.
> >>>>> > This is indeed a simple way to do very simple programming (but is
> >>>>> > hopeless for anything of reasonable complexity). These tools are also
> >>>>> > no open source or free.
> >>>>> >
> >>>>> > Fortuitously I got into a discussion with Timothy about PLC "ladder
> >>>>> > logic" programming. This could be a simple way to do very simple
> >>>>> > programs. There are a few very interesting open source ladder logic
> >>>>> > projects out there that compile a ladder and generate a "byte code"
> >>>>> > which runs on a tiny interpreter. These can be simple enough to run on
> >>>>> > a small AVR, moderate PIC, Linux box etc. Anything that can eat C.
> >>>>> >
> >>>>> > Ladder logic is a graphical representation of an electrical circuit
> >>>>> > that operates on inputs and outputs
> >>>>> > eg.
> >>>>> >  |     IN1   IN2  OUT1  |
> >>>>> > +-----[ ]---[ ]---( )------+
> >>>>> > |                                |
> >>>>> >
> >>>>> > If IN1 is on and IN2 is on then turn on output 1.
> >>>>> >
> >>>>> > Better descriptions in http://en.wikipedia.org/wiki/Ladder_logic
> >>>>> >
> >>>>> > A ladder logic tool I'm going to look at more is at
> >>>>> > http://www.cq.cx/ladder.pl
> >>>>> >
> >>>>> > --Charles
> >>>>> >
> >>>>> > _______________________________________________
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> >>>>>
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