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Title:Senzorsko vozlišče za merjenje okoljskih parametrov
Authors:Solar, Brina (Author)
Kos, Marko (Mentor) More about this mentor... New window
Files:.pdf UN_Solar_Brina_2018.pdf (1,57 MB)
 
Language:Slovenian
Work type:Diploma project paper (mb13)
Organization:FERI - Faculty of Electrical Engineering and Computer Science
Abstract:Z avtomatizacijo domovanj se je začelo pojavljati vse več možnosti za avtomatizacijo vrtov in kmetijskih površin. To je mogoče z uporabo senzorskih vozlišč, ki jih razporedimo po obdelovalni površini. Le-ta so zelo uporabna, saj omogočajo spremljanje okoljskih parametrov, ki lahko vodijo k slabšemu ali manj kakovostnemu pridelku. Z uporabo senzorskih vozlišč dobi pridelovalec možnost pregleda nad vplivom okoljskih parametrov in pravočasnega ukrepanja. Predvsem je tak način nadzora uporaben na večjih površinah, ki so pogosto precej oddaljene od prebivališča kmetovalca. Z razvojem senzorskih vozlišč se je pojavil tudi nov koncept kmetovanja, imenovan precizno kmetijstvo oz. agrikultura (ang. Precision agriculture). Ta temelji na opazovanju in merjenju okoljskih parametrov, na osnovi česar je mogoče izdelati sistem za avtomatsko oskrbovanje površin. Naša ideja je bila, da bi za zajem okoljskih parametrov uporabili več senzorskih vozlišč, enakomerno razporejenih po obdelovalni površini. Zato je bil glavni cilj projekta izdelati delujoči prototip vezja senzorskega vozlišča za merjenje okoljskih lastnosti in preizkusiti njegovo delovanje v realnem okolju. Senzorsko vozlišče, ki smo ga izdelali, je namenjeno merjenju temperature in vlage zraka, vlažnosti zemlje in zaznavanju prisotnosti sonca oz. osvetljenosti (posredno preko sončne celice). Za merjenje lastnosti zraka in zemlje smo uporabili ločena senzorja, osvetljenost pa smo merili s pomočjo ADC priključka na mikrokrmilniku. Zamislili smo si čim bolj avtonomno vezje, ki vsebuje sončno celico in rezervno baterijo. V dneh sončnega vremena bo sončna celica napajala vezje in hkrati polnila baterijo. Če pa bo vreme oblačno ali deževno, bo vir napajanja rezervna baterija. V okviru izdelave prototipa smo načrtali tiskanino za senzorsko vozlišče, izmerili karakteristike napajalnega dela vezja in primerjali delovanje sončnih celic različnih proizvajalcev, sprogramirali mikrokrmilnik za izvajanje meritev in testirali delovanje prototipa v realnem okolju. Mikrokrmilnik smo sprogramirali tako, da je zagotovljeno izvajanje meritev vsakih deset minut, po opravljenih meritvah pa gre celotno vezje v stanje spanja. Komunikacija med senzorji in mikrokrmilnikom za izvedbo meritev poteka preko komunikacijskega vodila TWI. V našem primeru je mikrokrmilnik prevzel vlogo gospodarja, senzorji pa vlogo sužnjev. Po opravljenih meritvah mikrokrmilnik pošlje rezultate meritev računalniku preko USART komunikacije. Izmerili smo spremembo polnilnega toka baterije in izkoristek napajalnega vezja glede na napetost na sončni celici. Dokler je napetost na sončni celici višja ali enaka 0,4 V, vezje kot glavni vir napajanja uporablja sončno celico in preko nje polni baterijo. Pri nižjih napetostih na sončni celici se zgodi preskok na napajanje vezja iz baterije, kar povzroči znatno povečanje izkoristka napajalnega vezja. Izmerili smo tudi spremembo toka v mikrokrmilnik glede na stanje, v katerem se nahaja (spanje/mirovanje ali izvajanje meritev). Po pričakovanjih je bil tok veliko manjši, ko je bil mikrokrmilnik v stanju spanja. Na koncu smo za boljši pregled nad realnim delovanjem senzorskega vozlišča opravili tedensko testiranje prototipa v naravi. Iz rezultatov je razvidno, da zračna vlažnost ponoči nekoliko naraste, temperatura zraka pa pade. Hitri prehodi na krivulji vlage zemlje predstavljajo trenutke, ko smo zalili gredo. Počasno naraščanje pa je posledica padavin. Ker je bila naša senzorska enota na zahodni strani, lahko vidimo, da tudi v sončnih dneh ni bila cel dan obsijana. Kratki padci napetosti na sončni celici prikazujejo kratkotrajno oblačnost. Za podrobnejši pregled sprememb napetosti na bateriji smo izvedli še tri-dnevno meritev, kjer smo beležili vrednosti napetosti na bateriji in sončni celici. Iz rezultatov je razvidno, da se napetost baterije ne zmanjša veliko (manj kot 5%). Z izdelavo prototipa senzorskega vozlišča smo zadostili vsem zadanim zahtevam projekta.
Keywords:senzorji, vozlišče, parametri, agrikultura
Year of publishing:2018
Publisher:[B. Solar]
Source:Maribor
UDC:621.3
COBISS_ID:22116118 Link is opened in a new window
License:CC BY-NC-ND 4.0
This work is available under this license: Creative Commons Attribution Non-Commercial No Derivatives 4.0 International
Views:221
Downloads:18
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Categories:KTFMB - FERI
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Secondary language

Language:English
Title:Project
Abstract:Home automation opened the door for automation of gardens and agricultural land. Which is possible through the use of sensor nodes, that are arranged over the cultivated area. They are very useful because they allow monitoring of environmental parameters that can lead to a worse quality of the yield. By using sensor nodes, the farmer will be given the opportunity to observe the impact of environmental parameters and act on it. In particular, this type of control is useful for larger areas, which are often far from the farmer's residence. With the development of sensor nodes, a new farming concept, called precision agriculture, was introduced. It is based on the observation and measurement of environmental parameters, which makes it is possible to create an automatic supply system for cultivated areas. Our idea was to use several sensor nodes evenly distributed across the cultivated area to capture environmental parameters. Therefore, the main objective of the project was to make a working prototype circuit of the sensor node for measuring environmental parameters and to test it in a real environment. We have designed a sensor node that can measure air temperature and humidity, soil humidity and presence of the sun or illumination (indirectly via a solar cell). Separate sensors were used to measure the properties of air and soil, and the illumination was measured using the AD converter on the microcontroller. We have designed an autonomous circuit containing a solar cell and a spare battery. In the days of sunshine, the solar cell powers the circuit and charges the battery at the same time. If the weather is cloudy or rainy, the main power source will be a spare battery. In the framework of the prototype design, we measured the characteristics of the power supply part of the circuit, compared to the characteristics of the solar cells of different manufacturers, programmed the microcontroller and tested the prototype in a real environment. The microcontroller was programmed to perform measurements every ten minutes, and after they are done, the whole circuit goes into sleep mode. The communication between the sensors and the microcontroller is carried out via the communication bus TWI. In our case, the microcontroller has the role of master, and sensors have the role of slaves. After the measurements are made, the microcontroller sends the results to the computer via communication USART. We measured the change in the charging current of the battery and the efficiency of the power supply circuit based on the voltage on the solar cell. As long as the voltage on the solar cell is higher than or equal to 0.4 V, the circuit uses the solar cell as the main source of power supply and charges the battery. At lower solar cell voltage value, the main power supply source is the battery, resulting in a significant increase in the efficiency of the power supply circuit. We also measured the change of current in the microcontroller according to its mode (sleep or measuring). As expected, the current was much smaller when the microcontroller was in sleep mode. For a better overview of the real functioning of the sensor node, we tested the prototype in a real environment. The results clearly show that the air humidity increases slightly at night, while air temperature decreases. The rapid transitions on soil moisture curve appeared we watered the plant. Since our sensor unit was on the west side, we can see that it was not illuminated during all day even though it was sunny. Short drops of voltage on the solar cell indicate short-term cloudiness. For a more detailed overview of voltage variations on the battery, we performed a three-day measurement, where we logged the voltage values on the battery and solar cell. The results show that the battery voltage does not decrease much (less than 5%). By creating a prototype for the sensor node, we met all the requirements of the project.
Keywords:sensor, node, parameters, precision agriculture


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