Bewässerung | 3l3c7r1c pl4y6r0und

When I started layouting the PCB for my irrigation sensor I realized the advantages of a breakout board. They are handy for developing, sure. But they also bear the big advantage that you do not have to take care about repetitive tasks (such as pull-up resistors). Additionally they ease up layouting by adding two additional layers to your design. That simplifies the design and it also minimizes the footprint of the final PCB.

Size was the most important factor for me. It isn’t just a question of space, it is also a question of price (PCB cost ist based on cm²). Beside the pull up resistors for CH_PD, GPIO_0, GPIO_2 and RESET and the buttons to ground RESET and GPIO_0 (PROG) I have also foreseen a pin header for connecting my XCSOURCE FT232RL USB<->TTL. The voltage supply of the USB-TTL converter can be enabled or disabled with a jumper. Additionally I have foreseen solder jumpers CTS->REST and DTR->GPIO_0. I’ve not tried personally but some sources say that this connections make the manual buttons obsolete by handing over this task to the USB-TTL converter. Finally there is also a solder jumper to connect GPIO_16 and RESET (for wake up after deep sleep) and a capacitor as voltage stabilizer. Other boards like the Huzzah Board use a voltage converter for this but I have made good experience with the capacitor.

My followers on twitter know that it took several attempts before I got my final version ready (special thanks here to @ccxx72, @i_grr, @bdcatalin und @tzapulica for their help). I also faced some troubles with Fritzing but finally you can download my result at Github: https://github.com/Stromspielplatz/misc/tree/master/ESP8266%20ESP-12%20Breakout

ESP8266-ESP12 Breakout Board Circuit Diagram

The easiest way to control automatic irrigation would be using the soil moisture as threshold value and start a pump with that. But I don’t think that this is a suitable approach to control watering of plants. The measuring value coming from the soil probe is rather more a reference point than a value to be used for a controller. I also want to implement a real controller keeping my soil moisture rather constant because I think that will lead to a better yield. The standard controller everybody knows is the PI-Controller. It is an ideal solution for many situations but in my case the disadvantage is that it can only process one measuring value. For sure there are some ways to deal with additional values such as feedforward or cascading but I won’t do that. I will use a Fuzzy Controller instead.

The Fuzzy Controller is a multi-input-multi-output (MIMO) control algorithm working with indistinct (fuzzy) definitions. That sounds very creative but the history goes back to 1965. In the 1990s there was a real hype about Fuzzy Control but then this concept sank into oblivion. In my opinion this control concept is still quite underestimated and unknown today and that’s very unfortunate because it deals well with the most common problems in controller design: no exact model and inly empirical knowledge about the needed algorithm.

I want to use our existing webserver so I will implement the controller in PHP. I have found a very nice class from Wojtek Jarzecji. The idea is that later on an Arduino will call the PHP script. The script will return a change request for the water setpoint (-10%…+10%). The Arduino will add this to the actual pump setpoint (0….100%) and transfer it to a pwm signal.

For the parameters I do some measurements in wet (~400) and in dry soil (~800). Google tells me that in my hometown average humidity is between 50% and 90% and temperature in summer times is between 8°C and 36°C. I take this values to define my input membership functions as follows:

That’s my script:

<!doctype html>
<!--?php
    require_once ('./fuzzy-logic-class.php');
    
    /*----------------Aktuelle Messwerte aus Datenbank anfragen----*/
    // <span class="hiddenSpellError" pre="" data-mce-bogus="1"-->MariaDB Server
    $servername = "IP-SERVER";
    $username = "USER";
    $password = "PASSWORD";
    $dbname = "templogg";

    // Create connection
    $conn = new mysqli($servername, $username, $password, $dbname);
    // Check connection
    if ($conn->connect_error) {
    	die("Connection failed: " . $conn->connect_error);
    }

    // Actual Values
    $sql = "SELECT `temp`,`humidity`,`soil` FROM `tbllogging` ORDER BY dt desc LIMIT 1;";
    $actual = $conn->query($sql);
    if ($actual->num_rows > 0) {
	// output data of each row
	while($row = $actual->fetch_assoc()) {
		$acttemp = number_format($row["temp"],0);
		$acthum = number_format($row["humidity"],0);
		$actsoil = number_format($row["soil"],0);
	}
    } else {
	echo "0 results";
    }

    /*----------------Fuzzy Parameters----*/
    $x = new Fuzzy_Logic();
    $x->clearMembers();
    /* ---------- set input members ---------*/
    $x->setInputNames(array('TEMP','HUMIDITY', 'SOIL'));
    $x->addMember($x->getInputName(0),'COLD',  0,  8, 25   ,LINFINITY);
    $x->addMember($x->getInputName(0),'WARM', 20, 35, 100  ,RINFINITY);
    $x->addMember($x->getInputName(1),'LOW', 0  ,40 ,60    ,LINFINITY);
    $x->addMember($x->getInputName(1),'HIGH',50 ,70 ,100   ,RINFINITY);
    $x->addMember($x->getInputName(2),'WET', 0,   400 ,650  ,LINFINITY);
    $x->addMember($x->getInputName(2),'DRY',550, 800 ,1025 ,RINFINITY);

    /* ---------- set output members ---------*/
    $x->setOutputNames(array('OUT'));
    $x->addMember($x->getOutputName(0),'LOWER',-10, -5 ,0 ,LINFINITY);
    $x->addMember($x->getOutputName(0),'RAISE',0, 5 ,10 ,RINFINITY);

    /* ---------- set rule table ------------ */
    $x->clearRules();
    $x->addRule('IF TEMP.WARM OR SOIL.DRY OR HUMIDITY.LOW THEN OUT.RAISE');
    $x->addRule('IF TEMP.COLD OR SOIL.WET OR HUMIDITY.HIGH THEN OUT.LOWER');


    /*---------- Get values from database and calculate output ----*/
    $x->SetRealInput('TEMP',	$acttemp);
    $x->SetRealInput('HUMIDITY' ,$acthum);
    $x->SetRealInput('SOIL' ,	$actsoil);
    $fuzzy_arr = $x->calcFuzzy();
    $Fuzzy = $fuzzy_arr['OUT'];
    echo $Fuzzy;
?>

<!doctype html>

<!--?php

require_once ('./fuzzy-logic-class.php');

/*----------------Aktuelle Messwerte aus Datenbank anfragen----*/

// <span class="hiddenSpellError" pre="" data-mce-bogus="1"-->MariaDB Server

$servername = "IP-SERVER";

$username = "USER";

$password = "PASSWORD";

$dbname = "templogg";

// Create connection

$conn = new mysqli($servername, $username, $password, $dbname);

// Check connection

if ($conn->connect_error) {

die("Connection failed: " . $conn->connect_error);

}

// Actual Values

$sql = "SELECT `temp`,`humidity`,`soil` FROM `tbllogging` ORDER BY dt desc LIMIT 1;";

$actual = $conn->query($sql);

if ($actual->num_rows > 0) {

// output data of each row

while($row = $actual->fetch_assoc()) {

$acttemp = number_format($row["temp"],0);

$acthum = number_format($row["humidity"],0);

$actsoil = number_format($row["soil"],0);

}

} else {

echo "0 results";

}

/*----------------Fuzzy Parameters----*/

$x = new Fuzzy_Logic();

$x->clearMembers();

/* ---------- set input members ---------*/

$x->setInputNames(array('TEMP','HUMIDITY', 'SOIL'));

$x->addMember($x->getInputName(0),'COLD', 0, 8, 25 ,LINFINITY);

$x->addMember($x->getInputName(0),'WARM', 20, 35, 100 ,RINFINITY);

$x->addMember($x->getInputName(1),'LOW', 0 ,40 ,60 ,LINFINITY);

$x->addMember($x->getInputName(1),'HIGH',50 ,70 ,100 ,RINFINITY);

$x->addMember($x->getInputName(2),'WET', 0, 400 ,650 ,LINFINITY);

$x->addMember($x->getInputName(2),'DRY',550, 800 ,1025 ,RINFINITY);

/* ---------- set output members ---------*/

$x->setOutputNames(array('OUT'));

$x->addMember($x->getOutputName(0),'LOWER',-10, -5 ,0 ,LINFINITY);

$x->addMember($x->getOutputName(0),'RAISE',0, 5 ,10 ,RINFINITY);

/* ---------- set rule table ------------ */

$x->clearRules();

$x->addRule('IF TEMP.WARM OR SOIL.DRY OR HUMIDITY.LOW THEN OUT.RAISE');

$x->addRule('IF TEMP.COLD OR SOIL.WET OR HUMIDITY.HIGH THEN OUT.LOWER');

/*---------- Get values from database and calculate output ----*/

$x->SetRealInput('TEMP', $acttemp);

$x->SetRealInput('HUMIDITY' ,$acthum);

$x->SetRealInput('SOIL' , $actsoil);

$fuzzy_arr = $x->calcFuzzy();

$Fuzzy = $fuzzy_arr['OUT'];

echo $Fuzzy;

Tag: Bewässerung

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Irrigation Part 7 – ESP8266 Breakout Board

Irrigation – Part 6: Fuzzy Control

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