[SS2S-Main] Re: temperature controller with arduino

  • From: Nathan Asdourian <rawliquid@xxxxxxxxx>
  • To: sugarshot@xxxxxxxxxxxxx
  • Date: Thu, 3 Jul 2014 03:14:32 -0700

I took a look at the pid library available for arduino and while it is
functional, unless I have the concepts wrong, it is less than ideal.
In my mind, while functioning properly, the modified control values should
rarely hit the limits, and the control loop should actively attempt to
maintain the target value.
The first obvious issue was that with a 2 degree deficit the control loop
was able to max out just as it started to see the temp change.
When I reset it slightly above the target temp, initially it would click on
and off  with the on cycle getting shorter and shorter....then the control
loop stayed bottomed out as the temp dropped right past the target...

My test setup was a basic 12v resistive heating element controlled by an
arduino through a relay, with a ds18b20 sitting on top of the heating
element and a thin plate of aluminum as a heat spreader between them..
The program took all of maybe 30m to put together and debug. No failsafes,
or error checking...just the control loop and temp sensor.
On Jul 2, 2014 3:28 AM, "waaslandwolf" <waaslandwolf@xxxxxxxxx> wrote:

> Mark,
> I understand where you're coming from. On one side of the spectrum you can
> buy an off the shelf rocket and push the launch button, on the other hand
> you can mine your own ore for metals to construct the rocket with from
> scratch. Anything in between is a question of which balance point you
> choose.
> David.
> On Tue, Jul 1, 2014 at 12:36 AM, Redacted sender monsieurboo@xxxxxxx for
> DMARC <dmarc-noreply@xxxxxxxxxxxxx> wrote:
>> Seems to me guys like Vicente epitomize the original Day 1 spirit of the
>> SS2S venture.  Looking back, and particularly considering the wealth of
>> talent and experience in our group, we surely could've met our altitude
>> goal years ago with a fundraising effort, COTS parts and APCP as the
>> motivator.  We chose a different path, partly as a salute to amateur
>> rocketeers throughout the decades who had to "roll their own" more often
>> than not.
>> Certainly we owe it to ourselves to make the best use of technology.
>> When SS2S was first conceived, there were no GPS modules available for what
>> we needed.  (IIRC, they hadn't even unlocked the high-accuracy version for
>> civilians yet.)   Today, of course, we'd look foolish if we didn't embrace
>> that kind of capability.  Sometimes there's only one sensible choice.  When
>> it comes to a homebrew curing oven, though, there's more than one path to
>> the top of that hill.   The usual tradeoff applies:  The cheaper, the
>> steeper!
>> I'm not suggesting there's any right or wrong here, or that anyone is
>> *not* totally in tune with the SS2S vibe.  In fact, as usual there's been a
>> wide response with lots of suggestions and options offered -- a win-win for
>> all of us, and exactly what I've come to expect from this group.  I mainly
>> wanted to tip my hat to Vicente, another guy who likes to build things from
>> scratch while spending no more than he has to.
>> Cheers,
>> Mark L.
>>  -----Original Message-----
>> From: John Doe <waaslandwolf@xxxxxxxxx>
>> To: sugarshot <sugarshot@xxxxxxxxxxxxx>
>> Sent: Mon, Jun 30, 2014 5:19 pm
>> Subject: [SS2S-Main] Re: temperature controller with arduino
>>  Either go with the PID if it meets your requirements on programming the
>> temperature profile, or with the BCS brewing controller which certainly
>> does.
>>  What I've learned from years of developing electronics: if it already
>> exists as a product, it is likely to be cheaper to buy it than to build it.
>> The time saved can be invested elsewhere.
>>  Which doesn't mean building isn't fun, educational etc, but if the
>> product is only a small part of a programme, It's better to get it out of
>> the way and proceed towards the bigger goal. When laying a 10.000 piece
>> puzzle you don't want to make each piece by hand, you just buy them and
>> focus on completing the puzzle.
>>  David
>> Op 30-jun.-2014 om 15:16 heeft Vicente Alvero Zambrano <
>> vicente_alvero_14@xxxxxxxxxxx> het volgende geschreven:
>>   Your opinion is to use the existing PID device?
>> > Subject: [SS2S-Main] Re: temperature controller with arduino
>> > From: waaslandwolf@xxxxxxxxx
>> > Date: Mon, 30 Jun 2014 14:21:03 +0200
>> > To: sugarshot@xxxxxxxxxxxxx
>> >
>> > I agree with Peter. Trying to save a mere 180$ by developing a solution
>> that already exists isn't good use of resources.
>> >
>> > > Op 30-jun.-2014 om 00:52 heeft Peter Johansson <
>> rockets4kids@xxxxxxxxx> het volgende geschreven:
>> > >
>> > > On Sun, Jun 29, 2014 at 6:36 PM, Vicente Alvero Zambrano
>> > > <vicente_alvero_14@xxxxxxxxxxx> wrote:
>> > >
>> > >> My idea is to use an old oven heater like the picture.
>> > >> With respect to the PID controller, maybe it is cheaper to do it
>> manually,
>> > >> without writing code.
>> > >
>> > > One option to consider -- and an advantage to going with a homebrew
>> > > solution -- is to simply read a configuration file containing the
>> > > temperature profile and PID tunings over over the serial port.
>> > >
>> > > This way you get the maximal possible control with the minimal
>> > > hardware cost and minimal software development time.
>> > >
>> > > -p.
>> > >
>> >

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