Re: Rtai Digest, Vol 98, Issue 6

On 02/21/2016 06:39 PM, gianluca wrote:
> Thanks All for Reply!
>
> I'll use a framegrabber camera(it's more speed). I'll make a task real 
> time that acquires one frame every T microseconds, and puts it into a 
> FIFO queue. A second task not real-time gets the frame from queue and 
> computes it thanks to OpenCv. Now because the second task isn't not 
> real time task how can I create a possible robot guidance 
> deterministic ? How can i implement a task that uses OpenCv in a 
> way more deterministic (to make a task real-time)? Exisit 
> libraries real-time to handles ethernet-ip communication if yes i have 
> to use always FIFO?
>
Use that lib directly in you real time code and, through RTAI, monitor 
the Linux syscalls it does. On the base of what you see you might 
understand if there is a way to staticalize the usagethe lib usage 
avoiding and/or supporting functions that use Linux syscalls to damage 
you real time.

 From the OpenCv I see site they say "OpenCV was designed for 
computational efficiency and with a strong focus on real-time 
applications." but i do not understand what that means.

Paolo
>
>
>
> > From: [email protected]
> > Subject: Rtai Digest, Vol 98, Issue 6
> > To: [email protected]
> > Date: Sat, 20 Feb 2016 12:00:03 +0100
> >
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> > 1. Re: Utilizzare RTAI per creare un sistema di visione real
> > time (SUPSI)
> >
> >
> > ----------------------------------------------------------------------
> >
> > Message: 1
> > Date: Sat, 20 Feb 2016 06:27:55 +0100
> > From: SUPSI <[email protected]>
> > To: [email protected]
> > Subject: Re: [Rtai] Utilizzare RTAI per creare un sistema di visione
> > real time
> > Message-ID: <[email protected]>
> > Content-Type: text/plain; charset="windows-1252"; Format="flowed"
> >
> > USB is not a good choice for a RT system: determinism is not 
> possible! A
> > soultion can be to create a task in Linux space to drive the USB camera
> > and send the result using fifos to the Linux RTAI task.
> >
> > Otherwise, we reach good results using a framegrabber and a 995fps
> > camera in a project implementing an adaptive optic for a solar 
> telescope..
> >
> > Best regards
> >
> > Roberto
> >
> > On 02/19/2016 07:46 PM, Giuliano Colla wrote:
> > > Not to reinvent the wheel, look first at http://www.ros.org/.
> > > In general however RTAI is more suitable to deal with real-time
> > > measurement data collection, where nanoseconds matter, with tasks
> > > which take a small fraction of CPU time.
> > > For a vision system I'd rather consider the Linux RT-kernel, with
> > > PREEMPT_RT patch (https://rt.wiki.kernel.org/index.php/Main_Page)
> > > which makes available all the OS features, with latencies in the
> > > microseconds region, as opposed to nanoseconds.
> > >
> > > [Italian translation]
> > > Per non reinventare l'acqua calda, io guarderei prima a
> > > http://www.ros.org/ - Robot Operating System.
> > > Comunque in generale RTAI ? pi? adatto per la raccolta di dati di
> > > misura con precisioni di qualche nanosecondo, che impegnano la CPU 
> per
> > > una piccola frazione di tempo.
> > > Per un sistema di visione, molto pi? complesso, io considererei
> > > l'utilizzo della versione real-time del kernel
> > > (https://rt.wiki.kernel.org/index.php/Main_Page), che rende
> > > disponibili tutte le funzionalit? del sistema operativo, anche se con
> > > latenze dell'ordine dei microsecondi anziche nanosecondi.
> > >
> > > Giuliano
> > >
> > > Il 19/02/2016 18:56, gianluca ha scritto:
> > >> Salve,
> > >>
> > >> Sono un neolaureato in Ing. dell'Automazione DM/270, e vorrei alcuni
> > >> consigli su e se ? possibile creare un sistema di visione real time
> > >> PC based che attraverso librerie OpenCV identifichi oggeti 
> attraverso
> > >> l'acquisizione di frame in real time da una telecamera (visione 2d)
> > >> in modo da implementare un guida-robot. Ho esperienza nella
> > >> programmazione in C e C++ e conosco le conoscenze di basi su ci? che
> > >> dovrebbe essere un sistema operativo real time. Per RTAI esistono
> > >> librerie USB real time che permettono l'acquisizione di immagini da
> > >> una telecamera? se ? si che caratteristiche dal punto di vista
> > >> hardware deve rispettare? Se il mio robot accetta il protocollo di
> > >> comunicazione industrial ethernet com'? garantito un determinismo?
> > >> Potreste fornirmi del materiale a riguardo?
> > >>
> > >> Grazie per la pazienza concessami, e con la presente Vi porgo i miei
> > >> saluti.
> > >>
> > >>
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