agreement, and addendum to Reproducibility and Monotonicity of sensor systems

Hi Morgan,

On 2011-03-19, at 3:17 PM, Morgan Sutherland wrote:

Hi Xin Wei,

As you know, the emphasis on linearity in electrical engineering is there so that we can be precise about what kinds of non-linearities we are introducing. It's about minimizing unknowns, not eliminating them.

My argument is only that if we use analog components, there is no possibility to design the behavior of f. Instead, f is effectively linear, by which I mean, it's roughly a straight line and we just have to deal with it as it is (we are at the whim of the non-linearity of the measurement, or the lack of meaningful correspondence between the measurement and the salient 'parameter', which is whether the plants should be watered or not and how much).

Of course, when we consider the whole entangled system, the LED will not vary linearly with the salient 'parameter' even if the system is "linear". But since we're going into the design without any knowledge of any of the functions except for f, it's wise to make sure that f is manipulable so that we can adapt it to the situation. In this case it's actually less labor intensive and possibly less energy/material intensive to design the system such that f is manipulable, though less elegant.


Well put.   Agreed.    This makes sense to me.   I call this "tuning"  (vs calibration, which is what the  "metal" system needs to do to normalize for contingent average conditions).   

See my response to Michal Re: ambiguity.

Again, well put.   
The formula you want may be slightly different:

Your point is now clear -- I agree down the line (so to speak).

Can someone else implement this in the microprocesser, freeing you up a bit ?

Re: photocells, that's a great point. It's too bad we're not going with distributed, wireless acquisition nodes because there's going to be a lot of wiring involved (like 20 feet per sensor).

This is an opportunity for Jane and others to think sculpturally.   Wire's form references the vines, twine, cables, so Jane and I think it's an opportunity to reflect "materially" on what is happening in our lab.  A little flexibility in the choice of color, gauge, and length etc. may be useful, if the electricals work as well.

Compliments.
Xin Wei

(PS I won't spam topologicalmedia@gmail.com, hoping Jane can pick this up in the blog at or before the next PLSS meeting. )

Reproducibility and Monotonicity of sensor systems

Hi Xin Wei,

The fact that we can't say that the system is linear does not mean that there is no space for intentionally introducing non-linearities into the system that have a qualitative effect on the perceived output.

As you know, the emphasis on linearity in electrical engineering is there so that we can be precise about what kinds of non-linearities we are introducing. It's about minimizing unknowns, not eliminating them.

When I say system, I mean the metal stuff. The metal stuff has a linear response according to the datasheet. That means that even though g is non-linear, I know that any non-linearities in f are designed.

My argument is only that if we use analog components, there is no possibility to design the behavior of f. Instead, f is effectively linear, by which I mean, it's roughly a straight line and we just have to deal with it as it is (we are at the whim of the non-linearity of the measurement, or the lack of meaningful correspondence between the measurement and the salient 'parameter', which is whether the plants should be watered or not and how much).

Of course, when we consider the whole entangled system, the LED will not vary linearly with the salient 'parameter' even if the system is "linear". But since we're going into the design without any knowledge of any of the functions except for f, it's wise to make sure that f is manipulable so that we can adapt it to the situation. In this case it's actually less labor intensive and possibly less energy/material intensive to design the system such that f is manipulable, though less elegant.

Put another way, I think that we can introduce non-linearities that will improve the entrainment process for the same reason that one musical instrument can be called better than another.

See my response to Michal Re: ambiguity.

I'm not sure what you mean by "ceramic wicks", but as for DIY analog methods, sensors involving electrodes and some sort of filtration medium (such as plaster) can't guarantee monotonicity and are subject to hysteresis, hence our going with commercial calibrated sensors. If we wanted to avoid electricity, then fingers work fine ;)

Re: photocells, that's a great point. It's too bad we're not going with distributed, wireless acquisition nodes because there's going to be a lot of wiring involved (like 20 feet per sensor).

Morgan

"system is effectively linear"

This is vague.   What's the "system"?   Reread Maturana and Varela, or Arakawa and Gins, or Heisenberg, Planck, Bohr.  Where does the organism begin and phenomenon end?   Maturana would remind us that "system" in the sense that you might mean it, meaning the electronic sensor + wires + microprocessor + code + wire + LED + battery + wire  is only  an artificial "god's eye view"  linguistic fiction.   (Read also the (in)famous essay about the artifactuality of physical measurement in gyro guidance system for ICBMs, reprinted in the Science Studies Reader, ed. Mario Biagioli.)

 

The mapping from soil humidity to human felt experience of the humidity is a composition of mappings, only some of which are computable, most of which are non-linear, most of which are in fact unknown.  Call these mappings f1, f2, ..., fn.

 

If f is linear, and g is non-linear, then  f º g  is non-linear.
If f and g are both non-linear, you have to be pretty damn lucky to find f º g linear.

 

Psycho-perception, alone, aside from anthropology and phenomenology, tells us that linearity is bogus.

 

In fact, the situation is far worse.   Since at least one of the factor mappings  fi  is indeterminate, even if all the other factor mappings were determined, the composition f1 º f2 º ... º fn  would still be indeterminate.

 

In fact the point of asking for monotonicity and reproducibility is precisely because that they together yield an "unambiguous" measure upon which individual humans can train.   "Reading" and  "unambiguous" are vague and paper over vast areas of uncertainty.   (Cf. the psych-perception literature; read Husserl.)   I suggested monotonicity and reproducibility as two practical qualities sometimes attainable by experimentalists with modest technical means.   At least if y'all achieve these two qualities in your sensor system, then we'll be able to muddle along.

 

To measure soil humidity, I bet there are ceramic wicks that'll do this totally analog, with no macro-current needed.  A chief value for doing digital is not so much to display humidity to the human, but its side effect: to get the humidity data into our Ozone system.   Speaking of which, I think we should run photo-cells into Ozone.   Maybe Claire can make some up from the Memory+Place leftovers -- asking Zohar, Patricia ?

 

Regards, Xin Wei

Links from PLSS Meeting (Electronics)

hi Jane, Hi Michal,

I agree with both Michal and Jane #1 :)

The  important issue is not merely soil humidity, not whether the sensor to LED path is analog or digital -  my digression with Morgan.  The issue is as Michal pointed out -- reminding us of when a particular plant needs water.  The delay, or anything requiring some memory is a good case for digital computation.  (this is a deep practical difference between analog and digital computation)

And yes, I think it makes sense to go with Jane #1, always: people's knowing habit, tacit knowledge, is always infinitely nuanced and richer than any  systematized schematized knowledge.  A "scientific" study could work, but it takes years of study to get beyond naive hacker amateur, who is less reliable than either gardener or mature botanist.  There's need to systematically get a degree in botany when Jane and Laura already know plants down to  your fingers  :)

(Mike Cooley, in Architect or Bee, has a thoughtful section about craft vs modularized info, and the mill wright.)

Xin Wei

On 2011-03-17, at 11:35 AM, jane tingley <janetingley@yahoo.com> wrote:

Hi Xin Wei - this mail was sent out - you were CCed but it bounced back...

Hi everyone

Michal brought up a good point.

As a recap - we discussed having a little analogue circuit on the humidity detector that has a POT ( a dial that we turn to either increase or decrease the detection of humidity)  So we put it in the plant when it is dry for example, to set the sensitivity.  We also discussed whether we should send the info to the arduino, and have the arduino turn the LED on and off. 

so// 
 there are two approaches we could take ...

1) Intuitive/tech
2) Science/tech

1) If we have a side circuit that controls the led, with a POT - then basically, when either Laura or I put the sensor in the plants, we dial the POT to adjust sensitivity.  We will use our knowledge of the plants to calibrate these sensors over a period of say a month.  So for example - With a yucca - a desert plant and generally needs a little bit of water  every two weeks.  Let's say the green LED comes on in the yucca after just 1 week of being watered, and the plant looks healthy, we would dial the sensitivity lower.  We would do this until the light goes on after what we believe - based on our knowledge of plants - is an appropriate amount of time.  This approach would be more intuitive, and require a couple of people who are knowledgable of plants to set up the system - as well as a lengthy calibration period.

2) We find out the actual science - what exact level of humidity a yucca needs to survive.  Send the data out to a computer, and then have the program turn the LED on when the plant needs to be water - based on the science.  We could then also use this data to take care of the plants during the summer.

Perhaps people have some opinions about which direction we should take.  I'm on the fence.
 
Jane Tingley

mobile    >> 514-245-0499
skype     >> jane.tingley
************************************

http://www.janetingley.com
http://www.saatchi-gallery.co.uk/yourgallery/artist_profile//27429.html


From: 
To:
Cc: 
Sent: Thu, March 17, 2011 10:09:31 AM
Subject: Re: Links from PLSS Meeting (Electronics)

Hi all,

Regardless of the microcontrollers/hardware and connectivity issue, I
too have some thoughts about what we discussed yesterday.  Going back
to the design of electronic circuit that includes indicators (LED) for
the plants, I think that the original idea of having a LED controlled
by the program/firmware, is in fact more appropriate one.  This is
because the plants need to be watered not only according to the
moisture level of the soil but also according to their needs (desert
plants can last a long time in dry soil).  This aspect should be
controlled either by the microcontroller or, preferably, a computer
program, which would be adjusted according to what kind of plants are
hooked up into the system.  In that case, a LED will go on only after
a certain time interval that the soil would have been dry.  I am not
sure about the analog dial (pot) for the circuit.  For a standalone
solution (microcontroller only) it would make sense to have some
relative control.  If this is going to be hooked up to a a computer
anyways, we could foresee programming a user interface which will
allow for specifying some kind of conditions per plant (I suppose this
would be preferred solution).

I hope I am making sense, please let me know if I am off the track
(wrt PLSS philosophy) or if something is unclear.

Best

Michal

On Wed, Mar 16, 2011 at 11:51 PM, Morgan Sutherland
< wrote:
> Hello Jane,
> If we want to use Ethernet rather than USB, I recommend using this WIZnet
> module which has an associated Arduino library so development is
> trivial: http://arduino.cc/en/Reference/Ethernet
> If you want to trade money for time, you can get the Arduino Ethernet shield
> (yes, it's compatible with the Seeeduino Mega), which is the same Wiznet
> chip: http://www.sparkfun.com/products/9026
> There are four advantages to ethernet that I can think of:
> (1) the cables are cheaper and you can make them to the exact length you
> need
> (2) there is no cable length limit
> (3) if the cable is accidentally unplugged, you don't need to restart your
> software in order to re-establish a connection, it's just always pushing the
> data onto the network without any "hand-shaking" required and
> (4) if we connect it to a switch (like the one on Michael's desk) the data
> is available to any computer in the lab – that would be useful for a day in
> the future when my computer is not located near the box.
> The downsides:
> (1) more development time
> (2) $30 extra
> I'd be curious as to why you were recommended another ethernet solution
> since this one is proven to work well and has an easy to use library.
> Morgan
> On Wed, Mar 16, 2011 at 6:21 PM, Morgan Sutherland
> wrote:
>>
>> Hi Jane,
>> Silicone conformal coating for protecting circuits from water:
>>
>> http://www.abra-electronics.com/products/422B%252dP-MG-Silicone-Conformal-Coating.html
>> The microcontroller we have + will use:
>>
>> http://www.seeedstudio.com/depot/seeeduino-mega-p-717.html?cPath=80&zenid=22b1d4d04f39a87446605e3c6bf360ef
>> Morgan
>

Reproducibility and Monotonicity of sensor systems

"system is effectively linear"

This is vague.   What's the "system"?   Reread Maturana and Varela, or Arakawa and Gins, or Heisenberg, Planck, Bohr.  Where does the organism begin and phenomenon end?   Maturana would remind us that "system" in the sense that you might mean it, meaning the electronic sensor + wires + microprocessor + code + wire + LED + battery + wire  is only  an artificial "god's eye view"  linguistic fiction.   (Read also the (in)famous essay about the artifactuality of physical measurement in gyro guidance system for ICBMs, reprinted in the Science Studies Reader, ed. Mario Biagioli.)

The mapping from soil humidity to human felt experience of the humidity is a composition of mappings, only some of which are computable, most of which are non-linear, most of which are in fact unknown.  Call these mappings f1, f2, ..., fn.

If f is linear, and g is non-linear, then  f º g  is non-linear.
If f and g are both non-linear, you have to be pretty damn lucky to find f º g linear.

Psycho-perception, alone, aside from anthropology and phenomenology, tells us that linearity is bogus.

In fact, the situation is far worse.   Since at least one of the factor mappings  fi  is indeterminate, even if all the other factor mappings were determined, the composition f1 º f2 º ... º fn  would still be indeterminate.

In fact the point of asking for monotonicity and reproducibility is precisely because that they together yield an "unambiguous" measure upon which individual humans can train.   "Reading" and  "unambiguous" are vague and paper over vast areas of uncertainty.   (Cf. the psych-perception literature; read Husserl.)   I suggested monotonicity and reproducibility as two practical qualities sometimes attainable by experimentalists with modest technical means.   At least if y'all achieve these two qualities in your sensor system, then we'll be able to muddle along.

To measure soil humidity, I bet there are ceramic wicks that'll do this totally analog, with no macro-current needed.  A chief value for doing digital is not so much to display humidity to the human, but its side effect: to get the humidity data into our Ozone system.   Speaking of which, I think we should run photo-cells into Ozone.   Maybe Claire can make some up from the Memory+Place leftovers -- asking Zohar, Patricia ?

Regards, Xin Wei

Reproducibility and Monotonicity of sensor systems

Thanks for the comments/synthesis Xin Wei,

(2) Linearity itself is meaningless because 
2.1  The relation between concentration of water to soil, or osmotic pressure to plant health is nonlinear and unknown (to the beholder in the TML);
2.2  The relation between electrical signal from sensor to cinput value in a piece of microprocessor code is nonlinear and unknown (to the programmer);
2.3  The relationship between chip output current and LED intensity as measured by a photometer at the eye of the beholder is nonlinear and unknown (to the programmer and to the beholder);
2.4  The relationship between LED intensity as measured by a photometer and the apparent intensity to the eye of the beholder is nonlinear and unknown to the beholder;
2.5  The relationship between one beholder and another beholder's sensitivity to LED intensity is nonlinear and unknown to the programmer.

This is good to point out, but I think that some points go without saying. When I say linear, I mean the system is effectively linear. 2.1 is definitely unknown in the strong sense, but 2.2 and 2.3 can be made effectively linear. In the end, however, 2.4 and 2.5 are highly non-linear due to ambient light and the innumerable nuances of experience. The reason to design the system to be non-linear, of course, is to make the reading less ambiguous (that is, to weaken the effect of 2.4 and 2.5). Still, one should always keep this in mind – thanks for stating it so succinctly.

The ONLY qualities that we should try to guarantee is that, for each given sensor in each given location:

I think that in addition to these two qualities, we should also do our best to insure that reading the LED's is an unambiguous as possible. This is the argument for using digital – going the analog route, given that we do not have a tremendous amount of expertise or time available, will result in an effectively linear relationship between the output of the sensor (which varies linearly with measured soil humidity) and the brightness of the LED, which leads to a very ambiguous signal.

This should be MUCH easier to implement, MUCH less work.

I actually disagree here. I think that passing the sensor values through the microcontroller and back out to the LED's will be slightly less work than making a delicate analog circuit, attaching it to each sensor, and water-proofing it, especially since I think we would need to use an op-amp + a few resistors per sensor. I have aesthetic preference for simple analog solutions vs. verbose digital solutions however.

 Minimax: Least engineering for Maximum experiential impact.

Ah, yes. Minimax > Worse is Better. (Indeed the author of the worse is better paper later repented and various papers were written about how it was a stupid and dangerous binary.)

Use analog first.   Digital only when you must, and understand what reductions you are incurring.

In this case the reductions are close to nil since at best we will apply a gentle curve to the data which otherwise would be identical to the analog 'values'. Maybe I'm underestimating the programming task (programming tends to eat time no matter how simple).

Thanks again,
Morgan

On Fri, Mar 18, 2011 at 8:52 PM, Sha Xin Wei <shaxinwei@gmail.com> wrote:
First, thanks to everyone for sharing this conversation because it affords a substantial comment.

Actually, Adrian's comments about thresholding and hysteresis are both deep and big issues, and, as Morgan pointed out, relevant to PLSS or any sensing problem :)   As Morgan pointed out, it is sufficient to leave a continuous map from water sensor to LED intensity. 

(1) So many assumptions are made converting from the analog world to a discrete representation that it  becomes meaningless to talk about "linear" relation between soil humidity to LED intensity.

(2) Linearity itself is meaningless because 
2.1  The relation between concentration of water to soil, or osmotic pressure to plant health is nonlinear and unknown (to the beholder in the TML);
2.2  The relation between electrical signal from sensor to cinput value in a piece of microprocessor code is nonlinear and unknown (to the programmer);
2.3  The relationship between chip output current and LED intensity as measured by a photometer at the eye of the beholder is nonlinear and unknown (to the programmer and to the beholder);
2.4  The relationship between LED intensity as measured by a photometer and the apparent intensity to the eye of the beholder is nonlinear and unknown to the beholder;
2.5  The relationship between one beholder and another beholder's sensitivity to LED intensity is nonlinear and unknown to the programmer.

The ONLY qualities that we should try to guarantee is that, for each given sensor in each given location:

1.  Reproducibility: same soil humidity yields the same LED intensity.
2.  Monotonicity:  soil humidity h1 > h2 => LED intensity[h1] > LED intensity[h2]
or vice versa if you wish: soil humidity h1 > h2 => LED intensity[h1] < LED intensity[h2]

This should be MUCH easier to implement, MUCH less work.

Given some average adjustments to accommodate for coarse limits like soil humidity ranges, and visibility of the LED's in the room under daylight conditions, leave it to us humans to each individually learn how to interpret the LED intensities.

Minimax: Least engineering for Maximum experiential impact.

Use analog first.   Digital only when you must, and understand what reductions you are incurring.

Regards,
Xin Wei

On 2011-03-17, at 12:10 PM, Morgan Sutherland wrote:

Hi Michal, (cc'ing Xin Wei by Jane's request),

My take is that the benefit doesn't justify the cost – 5-wires per node is a lot of wiring. But let's be more precise. Here's how I see it:

AFAIK the relationship between voltage-out from the sensor and soil humidity is reasonably linear. So the question is, does it make sense for the LED to vary linearly with soil humidity times some scalar (controlled by potentiometer), or should the response be non-linear, i.e. on-off, exponential, etc.?

My reading was that linear would be fine because we don't care about intermediate states. We don't need to exclude the middle because the human does it automatically. Approaching the LED, you will ask "is it bright, or not?" How likely is it that you will mistake an intermediate state for a higher or lower intermediate state?

I agree that adding something like an exponential curve for instance will make the readings clearer, but I'm not sure if it will be a problem. Maybe we should try it and see?

Another option would be to put a comparator on each sensor with a tunable threshold so that the LED just turns on when the plants need watering. I'd rather avoid this though for reasons that Adrian detailed recently (I'll forward the email if you're curious) – suffice it to say it's not in line with the TML Way.

A bigger problem that just occurred to me now is that the 'signal out' from the sensor might not vary current linearly with voltage (since the signal is carried on the voltage), which means that the LED might not dim if it's hooked up to the signal out as we suspected. In that case we might need to add an op-amp and some circuits to do the conversion: http://www.allaboutcircuits.com/vol_3/chpt_8/7.html – this would be best worked out with an analog guru like Martin.

So, my opinion is that it would definitely be better to control the LED's with the microcontroller, but only if it justifies the extra cabling and implementation complexity. My gut feeling is that an LED linearly coupled with the sensor reading (multiplied by a hand-tuned scalar) is sufficient for the task, but I could be wrong. (Another advantage to using the microcontroller is that we could easily swap the LED for another kind of feedback device (say, a speaker) later on.)

Morgan

P.S. Sometimes I worry that I take "worse is better" a bit too far...

On Thu, Mar 17, 2011 at 10:09 AM, Michal Seta <djiamnot@gmail.com> wrote:
Hi all,

Regardless of the microcontrollers/hardware and connectivity issue, I
too have some thoughts about what we discussed yesterday.  Going back
to the design of electronic circuit that includes indicators (LED) for
the plants, I think that the original idea of having a LED controlled
by the program/firmware, is in fact more appropriate one.  This is
because the plants need to be watered not only according to the
moisture level of the soil but also according to their needs (desert
plants can last a long time in dry soil).  This aspect should be
controlled either by the microcontroller or, preferably, a computer
program, which would be adjusted according to what kind of plants are
hooked up into the system.  In that case, a LED will go on only after
a certain time interval that the soil would have been dry.  I am not
sure about the analog dial (pot) for the circuit.  For a standalone
solution (microcontroller only) it would make sense to have some
relative control.  If this is going to be hooked up to a a computer
anyways, we could foresee programming a user interface which will
allow for specifying some kind of conditions per plant (I suppose this
would be preferred solution).

I hope I am making sense, please let me know if I am off the track
(wrt PLSS philosophy) or if something is unclear.

Best

Michal

On Wed, Mar 16, 2011 at 11:51 PM, Morgan Sutherland

<skiptracer@gmail.com> wrote:
> Hello Jane,
> If we want to use Ethernet rather than USB, I recommend using this WIZnet
> module which has an associated Arduino library so development is
> trivial: http://arduino.cc/en/Reference/Ethernet
> If you want to trade money for time, you can get the Arduino Ethernet shield
> (yes, it's compatible with the Seeeduino Mega), which is the same Wiznet
> chip: http://www.sparkfun.com/products/9026
> There are four advantages to ethernet that I can think of:
> (1) the cables are cheaper and you can make them to the exact length you
> need
> (2) there is no cable length limit
> (3) if the cable is accidentally unplugged, you don't need to restart your
> software in order to re-establish a connection, it's just always pushing the
> data onto the network without any "hand-shaking" required and
> (4) if we connect it to a switch (like the one on Michael's desk) the data
> is available to any computer in the lab – that would be useful for a day in
> the future when my computer is not located near the box.
> The downsides:
> (1) more development time
> (2) $30 extra
> I'd be curious as to why you were recommended another ethernet solution
> since this one is proven to work well and has an easy to use library.
> Morgan
> On Wed, Mar 16, 2011 at 6:21 PM, Morgan Sutherland <skiptracer@gmail.com>
> wrote:
>>
>> Hi Jane,
>> Silicone conformal coating for protecting circuits from water:
>>
>> http://www.abra-electronics.com/products/422B%252dP-MG-Silicone-Conformal-Coating.html
>> The microcontroller we have + will use:
>>
>> http://www.seeedstudio.com/depot/seeeduino-mega-p-717.html?cPath=80&zenid=22b1d4d04f39a87446605e3c6bf360ef
>> Morgan
>

Reproducibility and Monotonicity of sensor systems

First, thanks to everyone for sharing this conversation because it affords a substantial comment.

Actually, Adrian's comments about thresholding and hysteresis are both deep and big issues, and, as Morgan pointed out, relevant to PLSS or any sensing problem :)   As Morgan pointed out, it is sufficient to leave a continuous map from water sensor to LED intensity. 

(1) So many assumptions are made converting from the analog world to a discrete representation that it  becomes meaningless to talk about "linear" relation between soil humidity to LED intensity.

(2) Linearity itself is meaningless because 
2.1  The relation between concentration of water to soil, or osmotic pressure to plant health is nonlinear and unknown (to the beholder in the TML);
2.2  The relation between electrical signal from sensor to cinput value in a piece of microprocessor code is nonlinear and unknown (to the programmer);
2.3  The relationship between chip output current and LED intensity as measured by a photometer at the eye of the beholder is nonlinear and unknown (to the programmer and to the beholder);
2.4  The relationship between LED intensity as measured by a photometer and the apparent intensity to the eye of the beholder is nonlinear and unknown to the beholder;
2.5  The relationship between one beholder and another beholder's sensitivity to LED intensity is nonlinear and unknown to the programmer.

The ONLY qualities that we should try to guarantee is that, for each given sensor in each given location:

1.  Reproducibility: same soil humidity yields the same LED intensity.
2.  Monotonicity:  soil humidity h1 > h2 => LED intensity[h1] > LED intensity[h2]
or vice versa if you wish: soil humidity h1 > h2 => LED intensity[h1] < LED intensity[h2]

This should be MUCH easier to implement, MUCH less work.

Given some average adjustments to accommodate for coarse limits like soil humidity ranges, and visibility of the LED's in the room under daylight conditions, leave it to us humans to each individually learn how to interpret the LED intensities.

Minimax: Least engineering for Maximum experiential impact.

Use analog first.   Digital only when you must, and understand what reductions you are incurring.

Regards,
Xin Wei

On 2011-03-17, at 12:10 PM, Morgan Sutherland wrote:

Hi Michal, (cc'ing Xin Wei by Jane's request),

My take is that the benefit doesn't justify the cost – 5-wires per node is a lot of wiring. But let's be more precise. Here's how I see it:

AFAIK the relationship between voltage-out from the sensor and soil humidity is reasonably linear. So the question is, does it make sense for the LED to vary linearly with soil humidity times some scalar (controlled by potentiometer), or should the response be non-linear, i.e. on-off, exponential, etc.?

My reading was that linear would be fine because we don't care about intermediate states. We don't need to exclude the middle because the human does it automatically. Approaching the LED, you will ask "is it bright, or not?" How likely is it that you will mistake an intermediate state for a higher or lower intermediate state?

I agree that adding something like an exponential curve for instance will make the readings clearer, but I'm not sure if it will be a problem. Maybe we should try it and see?

Another option would be to put a comparator on each sensor with a tunable threshold so that the LED just turns on when the plants need watering. I'd rather avoid this though for reasons that Adrian detailed recently (I'll forward the email if you're curious) – suffice it to say it's not in line with the TML Way.

A bigger problem that just occurred to me now is that the 'signal out' from the sensor might not vary current linearly with voltage (since the signal is carried on the voltage), which means that the LED might not dim if it's hooked up to the signal out as we suspected. In that case we might need to add an op-amp and some circuits to do the conversion: http://www.allaboutcircuits.com/vol_3/chpt_8/7.html – this would be best worked out with an analog guru like Martin.

So, my opinion is that it would definitely be better to control the LED's with the microcontroller, but only if it justifies the extra cabling and implementation complexity. My gut feeling is that an LED linearly coupled with the sensor reading (multiplied by a hand-tuned scalar) is sufficient for the task, but I could be wrong. (Another advantage to using the microcontroller is that we could easily swap the LED for another kind of feedback device (say, a speaker) later on.)

Morgan

P.S. Sometimes I worry that I take "worse is better" a bit too far...

On Thu, Mar 17, 2011 at 10:09 AM, Michal Seta <djiamnot@gmail.com> wrote:
Hi all,

Regardless of the microcontrollers/hardware and connectivity issue, I
too have some thoughts about what we discussed yesterday.  Going back
to the design of electronic circuit that includes indicators (LED) for
the plants, I think that the original idea of having a LED controlled
by the program/firmware, is in fact more appropriate one.  This is
because the plants need to be watered not only according to the
moisture level of the soil but also according to their needs (desert
plants can last a long time in dry soil).  This aspect should be
controlled either by the microcontroller or, preferably, a computer
program, which would be adjusted according to what kind of plants are
hooked up into the system.  In that case, a LED will go on only after
a certain time interval that the soil would have been dry.  I am not
sure about the analog dial (pot) for the circuit.  For a standalone
solution (microcontroller only) it would make sense to have some
relative control.  If this is going to be hooked up to a a computer
anyways, we could foresee programming a user interface which will
allow for specifying some kind of conditions per plant (I suppose this
would be preferred solution).

I hope I am making sense, please let me know if I am off the track
(wrt PLSS philosophy) or if something is unclear.

Best

Michal

On Wed, Mar 16, 2011 at 11:51 PM, Morgan Sutherland

<skiptracer@gmail.com> wrote:
> Hello Jane,
> If we want to use Ethernet rather than USB, I recommend using this WIZnet
> module which has an associated Arduino library so development is
> trivial: http://arduino.cc/en/Reference/Ethernet
> If you want to trade money for time, you can get the Arduino Ethernet shield
> (yes, it's compatible with the Seeeduino Mega), which is the same Wiznet
> chip: http://www.sparkfun.com/products/9026
> There are four advantages to ethernet that I can think of:
> (1) the cables are cheaper and you can make them to the exact length you
> need
> (2) there is no cable length limit
> (3) if the cable is accidentally unplugged, you don't need to restart your
> software in order to re-establish a connection, it's just always pushing the
> data onto the network without any "hand-shaking" required and
> (4) if we connect it to a switch (like the one on Michael's desk) the data
> is available to any computer in the lab – that would be useful for a day in
> the future when my computer is not located near the box.
> The downsides:
> (1) more development time
> (2) $30 extra
> I'd be curious as to why you were recommended another ethernet solution
> since this one is proven to work well and has an easy to use library.
> Morgan
> On Wed, Mar 16, 2011 at 6:21 PM, Morgan Sutherland <skiptracer@gmail.com>
> wrote:
>>
>> Hi Jane,
>> Silicone conformal coating for protecting circuits from water:
>>
>> http://www.abra-electronics.com/products/422B%252dP-MG-Silicone-Conformal-Coating.html
>> The microcontroller we have + will use:
>>
>> http://www.seeedstudio.com/depot/seeeduino-mega-p-717.html?cPath=80&zenid=22b1d4d04f39a87446605e3c6bf360ef
>> Morgan
>

Centipedes

Hello everyone,

I'm so happy to have the watering system dripping away. Thanks to Morgan and Sam!! 

As you can see in these photos, there seems to be a growing centipede infestation in one of our boxes. I suspect this is from the past few days of constant watering - centipedes love cool, damp places. There is no real threat to the plants, but these little guys will soon start to cover the soil. I'm going to shut off the water on this box for now, and let the soil dry in between waterings. Hopefully this will discourage future generations of creepy bugs. If anyone has other suggestions, let me know!

 

PLSS Drip System Beta 2, Wednesday 2-3:30?

Congratulations, Morgan, Sam!   

Michal is mandated to ensure that the PLSS system 1.0 goes live as soon as possible.   We are very fortunate to have Michal's attention and experienced energy.  I've asked Jane to allocate central funding from the TML infrastructure fund to get PLSS done early enough to be of use to the TML strategically* before classes end, ie before April 1.

We are also lucky to have Jane's sculptoral attention.   When Jane, Michal and I met, we had some thoughts about the linear elements that seem more than ready for sculptural attention: the watering tubs, the plant stems, the hanging cables.   Jane may have some perspicacious ideas on what we can do with those elements.   Remember we also have video and sound, and electrical cables snaking through the room.   This is a unique opportunity, with Jane, to literally interweave aesthetic, symbolic, functional, material, botanical, and computational logics.

On 2011-03-12, at 8:20 PM, Morgan Sutherland wrote:

Hello all,

Sam and I fixed up the drip system today so that the plants in the boxes can be watered. Each box has 2 adjustable misters held up on bamboo sticks. The two misters can water a significant portion of the box without trouble.

We also made some notes about design going forward. We would like to complete the following tasks in March:

1. create a new support for the piano-frame with wheels
2. create two simple window boxes so we can grow more foodz (Laura, let me know if this is a good idea)
3. install an electronic master on/off valve and create a remote-control (design PCB w/ wireless radio + battery power)
4. design PCB for moisture sensors that send data back to computer wirelessly (copy design from Botanicalls)
5. design and build scaffolding for the watering tubes once they reach the box (the bamboo we're using right now is a bit ghetto – I would like to see laser-cut ply/acrylic, stiff wire, thin dowels might even be good enough...)

@Michal, let's meet next week to discuss your availability and what you can do from the above list. It would be nice if @Laura, @Sam and @Jane could be present too.

Suggested times:

Tuesday, 1pm-2pm
Wednesday, 12:00pm before Ozone
Wednesday, 5:30pm @ Campfire
Wednesday, 6:30pm after Campfire

Morgan

For PLSS 1.1 ?

Flower's vines creeping into the grid, the piano-planter, and the suspended "boat-planter"  have been three of the most striking elements of the TML.   It'd be great if PLSS 1.0 supports one or all of those elements.

* 
The strategic goals are:

(1) Have our plants can survive the summer;
(2) Document this system working in image, blog;
and 
(3) Publish PLSS work in one or more venues, such as:
(3.1) Journal of Environmental Philosophy Special Issue (due April 1);
and 
(3.2)  International Association for Environmental Philosophy meeting (abstract due March 15!).

The last is of course infeasible for a joint paper celebrating us would-be vegetal philosophers.  But  Jen may feel like  submitting a readymade abstract of her dissertation, and put in a good footnote adverting PLSS.   If I had time, I'd offer to write up an anthro-STS paper with Laura, et al.

After the practical work is settled at the Wed 2PM Eco-Eco mtg, I suggest quickly checking in with potential co-authors?

Xin Wei

PS. Helga Wild will be visiting and speaking on Wednesday.  I expect that she'll be with us for the latter part of the afternoon.


Temporal Environments: Rethinking Time and Ecology
Deadline: April 01 2011
Updated: January 16 2011
Special Issue of the Journal of Environmental Philosophy Editors:
Jacob Metcalf (UC Santa Cruz) and Thom van Dooren (University of
Technology, Sydney)

paper call for Gardening and Nesting groups

Laura, shall we meet Wed 2 PM next week to to talk about a paper?  
Jen if you're interested in joining us, you're welcome

Cheers, Xin Wei

Begin forwarded message:

Date: March 10, 2011 5:14:01 PM EST
To: "Sha Wei" <shaxinwei@gmail.com>
Cc: "p.a.duquette " <impetus@graffiti.net>
Subject: paper call for Gardening and Nesting groups

Whoops:
I meant Plant/Ecology  +  Memory/Place
groups of course:


Temporal Environments: Rethinking Time and Ecology
Deadline: April 01 2011
Updated: January 16 2011
Special Issue of the Journal of Environmental Philosophy Editors:
Jacob Metcalf (UC Santa Cruz) and Thom van Dooren (University of
Technology, Sydney)

Place and space have received substantial attention in environmental
philosophy in recent decades. Theorists from a variety of fields have
proposed that reorienting our relationship to the non-human world
requires reconsideration of ways of understanding and inhabiting
spaces and places. Ecophenomenologists have argued that replacing
meaningful places with abstract space was a critical moment in
histories of environmental destruction, and environmental ethics will
require re-imagining place as meaningful again. Bioregionalism has
emphasized the need to rethink our places as ecological relationships,
and inspired not only changes in academia, but also in environmental
movements such as food localism. In a related vein, Val Plumwood has
cautioned against too simplistic a notion of “one’s place”,
critiquing
the fracturing of place in which cherished homeplaces are able to be
preserved only as a result of the destruction of less visible ‘shadow
places’. In short, there is a broad assertion that reassessing our
obligations to more-than-human worlds requires understanding place as
more meaningful than an empty space to be filled by human concerns.

This special issue of the Journal of Environmental Philosophy will
present a collection of articles that direct similar attention to the
time and temporality of environments, a topic that has been relatively
neglected by environmental philosophy and ethics. Although
environmental ethicists have long discussed temporal issues, such as
intergenerational justice, time has often been treated as an
essentially linear and static container for human action. But if we
conceive of time as produced, constructed, maintained, lived,
multiple, and a more-than-human concern, the possibilities for
environmental philosophy look dramatically different. This collection
will offer such a framework for thinking through time and environment
by exploring the multiple lived times present in global climate
change, species extinction, the practices of ecological sciences, and
the temporal fidelities of conservation and restoration.

Among the questions we hope this collection might explore are: What
philosophical reconsiderations of time might be available and useful
for other ecological disciplines? How does the pace of human life—
markets, science, desires, consumption—impact our ability to imagine
and produce livable futures? How might we remember different, and
sometimes lost, ways of valuing human and nonhuman worlds in a way
that does not fetishize the past but still holds it open as a resource
for constructing better futures? How does an attentiveness to the
scope of evolutionary time alter our sense of obligation in a time of
massive biodiversity loss? How does the high-speed pace of much human
life actually make it harder to change the conditions of those lives?
How do humans and other animals learn to justly co-inhabit our
sometimes very different temporalities? What ways of life are enabled
or disabled by different temporal metaphors? What post-colonial
temporalities are necessary for recuperation of cultural ecologies
damaged by genocides and ecocides? Will sustainable ecologies require
new models of temporality to reformulate growth, degrowth, and
regrowth?

We invite submissions from environmental philosophers and other
ecological scholars, including reflective pieces from natural and
social scientists. Pieces that are grounded in specific cases of
temporal environments are especially encouraged. We welcome pieces
from international and native communities, and others not often
represented in philosophy `journals.

The Journal of Environmental Philosophy (http://
ephilosophy.uoregon.edu/) is a peer-reviewed professional philosophy
journal, and is the official journal of the International Association
of Environmental Philosophy (IAEP). The Journal of Environmental
Philosophy publishes innovative research relevant to all areas of
environmental philosophy, including ethics, aesthetics, metaphysics,
theology, politics, ecofeminism, environmental justice, philosophy of
technology, and ecophenomenology. Target publication date: Spring 2012
Abstracts of 300-400 words, due by April 1, 2011 Papers due for review
by August 1, 2011 There are no word count restrictions, but
submissions are encouraged to aim for 6-8,000 words. For further
information or to submit abstracts, please contact Jacob Metcalf
(jake.metcalf@gmail.com) or Thom van Dooren
(thom.van.dooren@gmail.com).