09-03-2011, 04:53 PM
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WIRELESS CONTROLLED GREEN HOUSE AUTOMATION
At this point in time, the world’s pollution problem has led to unpredictable weather conditions all over the world. With these ever changing weather conditions, it is expected that the number of greenhouses will significantly increase in the near future, thus leading to a great demand for automated
greenhouse monitoring systems
OBJECTIVE:-
The main goal is to build a miniature greenhouse which is equipped with an automatic
monitoring system. This monitoring system will constantly monitor the conditions in the
greenhouse to ensure that it remains at preset temperature, light and humidity conditions.
If these conditions differ from the preset levels, the monitoring system will automatically
turn on certain devices to return the greenhouse to the required conditions.
BENEFITS:-
Automatically control the growing environment within the walls so that
any type of plants can be grown all year round.
Eliminates the risk of the greenhouse not being kept at specified
conditions due to human error.
Minimizes the labor costs involved in maintaining a greenhouse.
Customer will be able to define their preferred greenhouse conditions and
have the system function as specified.
This will be a “plug-and play” product.
FEATURES:-
Detect temperatures from -40°C to 125°C.
Maintain a temperature of about 10°C to about 40°C.
Detect humidity between 5% RH and 95% RH.
Maintain a humidity of about 40% to 80% RH.
Detect sunlight and artificial light.
Turn on artificial lighting in the event that there is insufficient light.
OVER ALL DESIGN:-
For our Automated Greenhouse Monitoring System, we will implement 3 types of
sensors. The sensors to be used are photodiodes, a temperature sensor and a humidity
sensor. We will build a miniature greenhouse and determine the appropriate positions to
place the sensors. A series of tests will be done to make sure that all the sensors are
working accordingly. These sensors will be connected to a microcontroller which will
function as the main control unit. The sensors will send signals to the microcontroller and
the microcontroller will translate the signals and determine if the input is within the
preset range. For instance, if the preset temperature range is from 20oC to 25oC, the
microcontroller will make sure that the greenhouse temperature is within this range. If the
temperature exceeds the maximum value, the microcontroller will then turn on the fan. If
the temperature drops below the minimum value, the heater will turn on. As for the
photodiode, if the greenhouse is exposed to insufficient light, it will send a signal to the
microcontroller. The microcontroller will then process the signal and turn on the artificial
light in the greenhouse. As for the humidity sensor, it will detect a change in humidity
levels and send a signal to the microcontroller. If the humidity level is not within the
required range, the mister or exhaust fan will be turned on or off. The microcontroller
will be the central processing unit which will translate the input signals from the sensors
and turn on or off the necessary devices to maintain the greenhouse at the preset levels.
MAIN PARTS FUNCTIONS:-
PHOTODIODE:-
The Microsemi Light Detector (LX1972) will be used. After the sensor detects the
lighting conditions, it sends a signal to the microcontroller. The microcontroller analyzes
this signal and will then turn on or off the bulb
TEMPERETURE SENSOR:-
The Microchip Thermistor (MCP9700A) or LM35 will be used as it is capable of
detecting temperatures from -40°C to 125°C. This device is suitable as surrounding
temperatures should not go beyond this range. After the sensor detects the temperature, it
sends a signal to the microcontroller. The microcontroller analyzes this signal and then
turns on or off the fan or heater to bring the conditions back to the preset levels.
HUMIDITY SENSOR:-
The TDK Humidity sensor (CHS-U) will be used as it is capable of detecting humidity
levels from 5% RH to 95% RH. After the sensor detects the humidity level, it sends a
signal to the microcontroller. The microcontroller analyzes this signal and will then turn
on or off the mister or exhaust fan to bring the conditions back to the preset levels.
MICROCONTROLLER:-:
The MOT Microcontroller (PIC16F877A) will be used. It will be programmed using the
C language and will be capable of comparing the input signals from the sensors to the
preset values. The appropriate signal will then be output and used to either turn on or off
the devices.
DEVICES:-
In order to provide artificial light for the miniature greenhouse, an AC light-bulb will be
used. This will require using an AC Block Switch which will be controlled by the output
of the microcontroller. This AC switch will then pass the AC current through to the lightbulb.
For controlling the temperature in this project, if the surrounding temperature exceeds the
maximum preset level, a fan will be turned on. However, if the surrounding temperature
is below the minimum preset level, an LED will be used to indicate this. We have
decided not to use a heater in our miniature greenhouse due to the size and costs
involved.
To control the humidity, if the surroundings are too humid, an exhaust fan will be turned
on. However, if the surroundings are too dry, an LED will be used to indicate this. We
have decided not to use a mister in our miniature greenhouse due to the size and costs
involved.
