The most important factors for the quality and productivity of plant growth are temperature and humidity. Continuous monitoring of these environmental variables gives information to the grower to better understand, how each factor affects growth and how to manage maximal crop productiveness .The optimal greenhouse climate adjustment can enable us to improve productivity and to achieve remarkable energy savings - especially during the winter in northern countries. The system itself was usually simple without opportunities to control locally heating, lights, ventilation or some other activity, which was affecting the greenhouse interior climate. This all has changed in the modern greenhouses. The typical size of the greenhouse itself is much bigger what it was before, and the greenhouse facilities provide several options to make local adjustments to the lights, ventilation, heating and other greenhouse support systems. However, more measurement data is also needed to make this kind of automation system work properly. Increased number of measurement points should not dramatically increase the automation system cost. It should also be possible to easily change the location of the measurement points according to the particular needs, which depend on the specific plant, on the possible changes in the external weather or greenhouse structure and on the plant placement in the greenhouse.
For the implementation of agricultural technologies, low cost and real time remote monitoring are needed, in this sense, programmable Logic Devices (PLDs) present as a good option for the technology development and implementation.
Crop growth is mainly influenced by the surrounding environmental climatic variables and by the amount of water and fertilizers supplied by irrigation. This is the main reason why a greenhouse is ideal for cultivation, since it constitutes a closed environment in which climatic and fertirrigation variables can be controlled to allow an optimal growth and development of the crop. The climate and the fertirrigation are two independent systems with different control problems. Empirically, the requirements of water and nutrients of different crop species are known and, in fact, the first automated systems were those that controlled these variables. As the problem of greenhouse crop production is a complex issue, an extended simplification consists of supposing that plants receive the amount of water and fertilizers that they require at every moment. In this way, the problem is reduced to the control of crop growth as a function of climate environmental conditions.
India is an agriculture–oriented country. For the quality and Productivity improvement of greenhouse crops, it is necessary to measure and control several interacting physical variables. These tasks can only be accomplished by ‘control systems with built in software’. Erecting greenhouse is expensive. Automation machinery is imported in India hence it is expensive. Many farmers cannot adopt the greenhouse technology due to its high cost. Our project highlights about the approach to control the environment in Greenhouse. The greenhouse controller senses the changes in the temperatures (Dry temperature, Wet temperature) through input sensors and processes to take control action.
The proposed system is an embedded system which will closely monitor and control the microclimatic parameters of a greenhouse on a regular basis round the clock for cultivation of crops or specific plant species which could maximize their production over the whole crop growth season and to eliminate the difficulties involved in the system by reducing human intervention to the best possible extent.
The system comprises of
When any of the above mentioned climatic parameters cross a safety threshold which has to be maintained to protect the crops, the sensors sense the change and the fpga reads this from the data at its input ports after being converted to a digital form by the ADC. The fpga then performs the needed actions by employing relays until the strayed-out parameter has been brought back to its optimum level. Since a fpga is used as the heart of the system, it makes the set-up low-cost and effective nevertheless.
To implement a real time monitoring system for agricultural field low cost is a significant factor. In that sense programmable logic device(PLD) is a good option for the technology development and implementation, because PLD’s allow fast development of prototype and the design of complex hardware system using FPGA’S and commercial PLD’s.
Temperature for plant (flowers or vegetables) growth required is Day temperature around 26degreeC to 30degreeC Night temperature around 15 degree C to 18 degree C This temperature can be controlled using ventilation or fan pad cooling systems.
For floriculture 70% to 80% humidity should be maintained and for vegetables 60% to 70% humidity is required. Humidifiers or foggers are used to maintain this humidity range.
The LM35 series are precision integrated-circuit temperature sensors, whose output voltage is linearly proportional to the Celsius (Centigrade) temperature. The LM35 thus has an advantage over linear temperature sensors calibrated in ° Kelvin, as the user is not required to subtract a large constant voltage from its output to obtain convenient Centigrade scaling. The LM35 does not require any external calibration or trimming to provide typical accuracies of ±¼°C at room temperature and ±¾°C over a full -55 to +150°C temperature range. Low cost is assured by trimming and calibration at the wafer level. The LM35's low output impedance, linear output, and precise inherent calibration make interfacing to readout or control circuitry especially easy. It can be used with single power supplies, or with plus and minus supplies. As it draws only 60 μA from its supply, it has very low self-heating, less than 0.1°C in still air. The LM35 is rated to operate over a -55° to +150°C temperature range, while the LM35C is rated for a -40° to +110°C range (-10° with improved accuracy). The LM35 series is available packaged in hermetic TO-46 transistor packages, while the LM35C, LM35CA, and LM35D are also available in the plastic TO-92 transistor package. The LM35D is also available in an 8-lead surface mount small outline package and a plastic TO-220 package.
Digital Temperature controller which can make a Agricultural environment automated. People can control their electrical devices via Digital Temperature controller and set up the controlling actions in the computer. We think this product have high potential for marketing in the future.
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