LITERATURE REVIEW
This session discuss on the overall project
theory and concept. The purpose of this is to explain the perspective and
method that is used in previous research or project and to classify how much
this project related with those research and theory. Moreover, this session
will show the theory and concept used to solve problem. Theoretical is very
important as a guidelines in doing any kind of research.
1) SELECTION OF CONTROLLER
After
researching on the various types of controller, two have been shortlist:-
Type
|
Voltage
|
PLC
|
Need
at least 24 volt to operate system
|
PIC
microcontroller
|
Need
at least 5 volt to operate system
|
A microcontroller is a highly
integrated chip which performs controlling functions. A microcontroller, or
embedded controller, is similar to a microprocessor as used in a personal
computer, but with a great deal of additional functionally combined onto the
same monolithic semiconductor substrate. Microcontrollers, sometimes referred
to as one-chip microcomputers, are used to control a wide range of electrical
and mechanical appliances. Since they were first introduced, microcontrollers
have involved to the point where they can use for increasing complex
applications. Some microcontrollers in use today are also programmable,
expanding the number of application in which they can be used [2]. The PIC
microcontroller is chosen one because PIC only needs 5 Volt supply voltage to
operate compared to PLC (Programmable Logic Control) that requires a higher
voltage which is 24 volt. In addition, the price of PIC microcontroller is much
cheaper compared to the PLC.
2) SELECTION OF SENSOR
A sensor is a device
which measures a physical quantity and converts it into a signal which can be
read by an observer or by an instrument. Because sensors are a type of
transducer, they change one form of energy into another. For this reason,
sensors can be classified according to the type of energy transfer that they
detect. Soil moisture measurements provide useful information for agriculture,
such as grape growers, soil stability monitoring, dam monitoring and
construction activities.
A typical greenhouse
contains several sensors form measuring humidity, temperature, pressure, carbon
dioxide, light, motion, etc, and contains several actors, such as, air conditioners,
floodlights, sprinkler and water management facility, plant decks, air blowers,
fans, CO2 production units, etc. In this project will only consider the LDR
light, temperature and humidity sensor of the greenhouse [3].
2) SELECTION OF WATER FLOW
To make the watering
system to be better, these system use the aquarium pump to change it with the
solenoid valve. From the main pipe, the water will be stored in the tank. The
tank also has the buoyed to automatically stop the incoming water to the tank
or to store it when the tank is empty.
The high pressure water has been needed to flow the water because
separate the water using tube pipe. So, because these statements the aquarium
pumps already choose to replace with solenoid valve. So, it can give the
adequately pressure for the watering system.
2) SELECTION OF WAVELENGTH FOR OPTIMUM GROWTH
It shows two absorption maximum in the blue and
red portions in the spectrum. Blue is at the high-energy end of the spectrum,
so light of this wavelength is responsible for this much excitation and
explains the absorption peak in the blue. Red wavelengths are lower in energy
and only boost the electron to a lower energy level than can blue light. The
blue wavelength it’s able to create food for leaf (vegetative) and makes it essential
for the production of strong, thick leaves and stems. While red wavelength
stimulates vegetative growth and flowering but if a plant gets too much red
light, it will become tall and spindly. Typically it’s too hot to place
near enough for the plant to receive adequate amounts of light [4].
