Re: Ada, the best language with the not-so-best tool chain

[kalvin.news@gmail.com]

keskiviikko, 10. lokakuuta 2012 16.13.41 UTC+3 Simon Clubley kirjoitti:
> On 2012-10-10, Dmitry A. Kazakov <mailbox@dmitry-kazakov.de> wrote:
> 
> > On Tue, 9 Oct 2012 23:23:11 +0000 (UTC), Simon Clubley wrote:
> 
> >
> 
> >> Let's make this discussion more tangible by using a specific example.
> 
> >> 
> 
> >> The scenario: a hobbyist/academic researcher/whoever is building a
> 
> >> small computer controlled model aircraft, in the order of up to about
> 
> >> a metre in length for the fuselage.
> 
> >
> 
> > I have no idea about controlling an aircraft. Can one do it without a
> 
> > multitude of analogue inputs and outputs, rotary encoders etc?
> 
> >
> 
> 
> 
> [Remember we are talking about model aircraft here, not large human
> 
> carrying multi-million dollar/euro/pound aircraft.]
> 
> 
> 
> The interface problem is actually two sub-problems: (1) gathering sensor
> 
> data and (2) commanding the aircraft to move as a result of processing
> 
> the sensor data.
> 
> 
> 
> The input sensors are generally (but not always) digital these days.
> 
> For example, the low cost gyros and accelerometers you would typically
> 
> use usually have a SPI or I2C interface.
> 
> 
> 
> Commanding a model aircraft to move is done in exactly one way: by
> 
> sending command pulses to a standard R/C aircraft servo. The following
> 
> explains how these servos work:
> 
> 
> 
> http://en.wikipedia.org/wiki/Servo_%28radio_control%29
> 
> 
> 
> The length of the pulse determines the position of the servo.
> 
> 
> 
> Electronic speed controllers (the controller used to regulate power
> 
> to the electric motor driving the propeller) work in the same way;
> 
> pulses are sent along a command line.
> 
> 
> 
> These pulses are digital in nature; driven to logic 1 for a period of
> 
> time and then driven to logic 0 to end the pulse. They are ideally
> 
> suited to be connected to a GPIO line in output mode.
> 
> 
> 
> >> Question 1: if you could not use GPIO lines to control commodity
> 
> >> R/C components, how would you have the onboard computer control the
> 
> >> engine and flight control surfaces ?
> 
> >
> 
> > ARM boards look very much like a compromise. That rarely pays off. Likely
> 
> > there exist better solutions for a model aircraft, but I cannot judge that.
> 
> >
> 
> 
> 
> I would welcome suggestions as I cannot currently think of any viable
> 
> alternatives to a small and low power general purpose onboard computer.
> 
> 
> 
> >> To make this on topic for this newsgroup, this seems to be a common
> 
> >> hobbyist or researcher project in a number of circles, and is _exactly_
> 
> >> the type of project for which Ada would be very well suited indeed.
> 
> >
> 
> > How many people spend their time building model aircrafts? Could rail
> 
> > transport modeling be a better candidate?
> 
> >
> 
> 
> 
> When you look around, it seems a surprising amount of people do (or at
> 
> least they consider it). Compared to making a aircraft fly through the
> 
> air, rail transport modeling seems kind of boring in comparison. :-)
> 
> 
> 
> > Anyway, if you need an altimeter instrument for the ground control system,
> 
> > let me know. I maintain an instrumentation library in Ada.
> 
> >
> 
> >> Question 2: how would you put the idea of using Ada for this project
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> >> into someone's head and what changes to the Ada ecosystem would be
> 
> >> needed to make it viable for people with different ranges of embedded
> 
> >> experience to actually use Ada in this case ?
> 
> >
> 
> > I would tell him that he could use the same software during modeling and
> 
> > deployment phases, basically, doing much of the work in doors rather than
> 
> > in field.
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> >
> 
> 
> 
> The answer would need to be more specific than that; there already exist
> 
> testing environments which allow you to do some work on your control systems
> 
> indoors. For example, have a look at Flightgear: http://www.flightgear.org/
> 
> 
> 
> Quite a few people use it for developing parts of their system within a
> 
> simulated environment.
> 
> 
> 
> A person would generally need to be using arguments along the lines of
> 
> suggesting that Ada based development would result in more robust and/or
> 
> quicker to develop code.
> 
> 
> 
> Simon.
> 
> 
> 
> -- 
> 
> Simon Clubley, clubley@remove_me.eisner.decus.org-Earth.UFP
> 
> Microsoft: Bringing you 1980s technology to a 21st century world

Here is a nice page about Drones: http://diydrones.com/
Maybe this will give some hints about the size and power consumption restrictions. Anyway, these projects are good candidates for bare-metal Ada: Embedded, robust real-time systems.