Smart Greenhouse
Proposal
S13-41-SRGN
Jessica Lynn Suda - EE
Chase Cooley - EE
Gabriel Stefenon - ME
Brett Delaney (PM) - ECE
Client: Richard Cole
Faculty Advisors: Adam Watkins, Dr. Alan Weston
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Transmittal Letter (BD)
April 3, 2013
Saluki Engineering Company
Southern Illinois University Carbondale
College of Engineering
Carbondale, IL 62902
Mr. Richard Cole
Department of Plant Biology
Southern Illinois University Carbondale
Carbondale, IL 62902
(618)-453-2634
Dear Mr. Richard Cole,
This letter is in response to your request to design an automated greenhouse, and to inform you that we
will be prepared to begin the assembly of the Smart Greenhouse as early as October. We would also like
to thank you for your willingness to review our proposal. Many of us here at the Saluki Engineering
Company are very excited to be working with you.
Attached to this letter is our design proposal as well as some research we have done within the past few
months. As you have requested, we based our research off the requirement that the system must
autonomously sustain a high humidity/temperature environment suitable for Carnivorous plants, and to
allow for remote monitoring and reconfiguration of plant settings. We have found that the best way to go
about this is with the use of an Arduino microcontroller in conjunction with a PID control algorithm. This
controller will have the ability to read sensory data, and adjust the confined environment through multiple
actuators. Additional features of the Smart Greenhouse include a simplistic online user interface and a
power scheme to allow for minimal power usage.
After reviewing our combined work, we are confident that our proposal exceeds the given requirements.
Included in the design proposal is our literature review, a review of some required subsystems, and
additional documents detailing our future plans. If you require any further information, please call or email
me at your convenience.
Again, thank you for this opportunity.
Sincerely,
Brett Delaney
___________________________________
Project Manager, Smart Greenhouse Team
Saluki Engineering Company
197 Pine Shore Drive
Carbondale, Il 62902
(585)-857-3467
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Executive Summary (JLS)
With use of modern-day technology, the Smart Greenhouse control unit will allow the user will
stray from the tedious job of tending to the nutritional needs of plants. Under one interface, one
can monitor important plant growth factors, such as lighting, soil moisture, relative humidity, and
temperature, as well as monitor incoming power sources to be used to operate greenhouse
equipment. The autonomous system will nurture the plants without the user being present,
under a pre-set range of optimal conditions, while having the ability to run more efficiently off of
alternative energy sources. The proposed control unit project cost is estimated at $427 and will
be complete by November 25th, 2013.
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Restriction on Disclosure of Information (CLC)
The information provided in or for this proposal is the confidential, proprietary property of
the Saluki Engineering Company of Carbondale, Illinois, USA. Such information may be used
solely by the party to whom this proposal has been submitted by Saluki Engineering Company
and solely for the purpose of evaluating this proposal. The submittal of this proposal confers no
right in, or license to use, or right to disclose to others for any purpose, the subject matter, or
such information and data, nor confers the right to reproduce, or offer such information for sale.
All drawings, specifications, and other writings supplied with this proposal are to be returned to
Saluki Engineering Company promptly upon request. The use of this information, other than for
the purpose of evaluating this proposal, is subject to the terms of an agreement under which
services are to be performed pursuant to this proposal.
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Table of Contents
1. Technical Details
i. Introduction (BD)
ii. Literature Review (BD,JLS,GRS,CLC)
iii. Design Basis (CLC)
iv. Description (JLS)
v. List of Deliverables (CLC)
vi. Specifications (BD,JLS,GRS)
vii. Block Diagram (BD,JLS,CLC)
viii. Control Subsystem (BD)
ix. Heating/Cooling/Watering Subsystem(GRS)
x. Power Subsystem (JLS)
xi. User Interface (CLC)
xii. References
Page(s)
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2. Commercial
i. Budget Justification (GRS)
ii Resources Needed (GRS/JLS)
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3. Management
i. Organizational Chart (BD)
ii. Timeline (BD)
iii. Action Item List (BD)
iv. Resumes (BD, JLS, GRS, CLC)
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30
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TECHNICAL DETAILS
Introduction
Automated greenhouses have become widely popular among professional greenhouse
caretakers and hobbyists alike. With the advent of newly affordable technologies such as
microcontrollers and environmental sensors, engineers and hobbyists have devised ways to cut
plant maintenance to a minimum. While some automated greenhouses require little to no
additional caretaking, others are simplistic and control only limited functions such as watering
and timed lighting. By allowing as much automation as possible, the Smart Greenhouse will
reduce the amount of time spent caretaking for plants, and eliminates worry when a user is
away for long durations.
Automated growth environments can be extremely costly - some of which cost more than
$6000. These expensive grow boxes/greenhouses include high end components that are
unnecessary to sustain long term life support for plants, and since the market is relatively small,
these prices can be justified through the manufacturer. The Smart Greenhouse, however, is
expected to cost less than $500 and provide additional functionality such as remote monitoring
and reconfiguration. Additionally, the Smart Greenhouse can be marketed towards consumers
with little or no experience in growing plants, and will be easy to use.
In general, the Smart Greenhouse has three main goals:
1) Plant Survivability and Optimized Growth
2) Simplistic User Control/Interface with Remote Connectivity
3) Minimal Resources (power usage, water, fertilizer)
Plant survivability and idealized growth being the most important item is often of major
importance among other professional designs. However, this being the only focus leads to
problems such as usability and ease of use among less experienced plant growers. This is
where the Smart Greenhouse will capitalize: simplicity. Allowing for minimal human intervention
through automated tasks and a simple interface, the system will be useable among anyone.
Lastly, by incorporating techniques such as dynamic power distribution, the system will cost less
to run at a constant. Each of these goals are detailed throughout the Subsystems section within
this proposal.
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LITERATURE REVIEW
I.
Introduction
The objective of our research is to examine and explore various concepts that intertwine
with the proposed project - the Smart Greenhouse. There are four areas in which we will cover:
plant growth, environmental control methods,power distribution and efficiency, and control
units. Each of these topics will be reviewed through related research and publications. Much of
what we review may not be incorporated into our overall design. However, they should give
reasonable insight on the feasibility of certain aspects of the design, and provide new overall
ideas to the project.
II.
Greenhouse Cultivation and Advancements (CLC)
Emperor Tiberius of Rome (42 BCE–37 CE) is thought to be the first person to utilize a
structure that can be considered a greenhouse. He did this to be able to eat his favorite food all
year long, many guess that this food was the humble cucumber, this love of food started a new
wave of agriculture and it is this specific form of agriculture that this paper looks to examin. [1]
The first thing to decide when faced with designing a greenhouse is to consider the
structure you are going to be using. There are four different categories of greenhouses each
with their own benefits and drawbacks to consider:
“ Lean-to. A lean-to greenhouse is a half greenhouse, split along the peak of the roof, or
ridge line (Figure 2A), Lean-tos are useful where space is limited to a width of approximately
seven to twelve feet, and they are the least expensive structures. The ridge of the lean-to is
attached to a building using one side and an existing doorway, if available. Lean-tos are close to
available electricity, water and heat. The disadvantages include some limitations on space,
sunlight, ventilation, and temperature control. The height of the supporting wall limits the
potential size of the lean-to. The wider the lean-to, the higher the supporting wall must be.
Temperature control is more difficult because the wall that the greenhouse is built on may
collect the sun's heat while the translucent cover of the greenhouse may lose heat rapidly. The
lean-to should face the best direction for adequate sun exposure. Finally, consider the location
of windows and doors on the supporting structure and remember that snow, ice, or heavy rain
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might slide off the roof or the house onto the structure.
Even-span. An even-span is a full-size structure that has one gable end attached to another
building (Figure 2B). It is usually the largest and most costly option, but it provides more usable
space and can be lengthened. The even-span has a better shape than a lean-to for air
circulation to maintain uniform temperatures during the winter heating season. An even-span
can accommodate two to three benches for growing crops.
Window-mounted.
A window-mounted greenhouse can be attached on the south or east side of a house. This
glass enclosure gives space for conveniently growing a few plants at relatively low cost (Figure
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2D). The special window extends outward from the house a foot or so and can contain two or
three shelves.
Freestanding Structures
Freestanding greenhouses are separate structures; they can be set apart from other buildings to
get more sun and can be made as large or small as desired (Figure 2C). A separate heating
system is needed, and electricity and water must be installed.”[2]
Because of the design constraints of our project we are going to be employ the freestanding
structure greenhouse model. This structure is the most suitable option for a small scale
greenhouse and the cheapest per square foot option.
The next item to consider is the building materials themselves, there are many options to
consider when it comes to materials but a thorough explanation of each material is beyond the
scope of this paper. Instead the focus will be glass, this is the most traditional material and for
this project it happens to be more cost effective. Glass also offers a more stable structure and
is nearly 100% efficient at allowing light through to our plants. It won’t discolor over time like the
plastic options will and it offers an all around nice feel and look.
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The final piece of the greenhouse puzzle is what crop will be grown. Carnivorous plants
have been chosen for this project due to a few different factors. The first being the conditions in
which it they grow. Most carnivorous plants live in wet humid,low light environments with poor
soil conditions.[3] These conditions are why it is thought that the carnivorous plants evolved to
be able to process the insects they catch, to make up for the lack of nutrients in the soil and lack
of sunlight.[4] These characteristics allow for the greenhouse to be able to have a plant that is
rugged but with still enough need for specific controlled variables to show the projects abilities.
The second factor in the decision to use carnivorous plants is that they are marketable even on
a small scale such as the one we are using. The final reason which ties into the second
somewhat is the “neat” factor of the plants. Carnivorous plants have a way of attracting people
unlike most other plants, people have been and will continue to be fascinated by the insect
capturing mechanisms of these plants for as long as they are around.
III.
Ventilation, Heating, and Cooling (GBR)
1. VENTILATION
Ventilation is a major factor of climate control in a greenhouse, and influences the
efficiency, quality and yield. According to Zabeltitz, the main objectives of ventilation is the
exchange of carbon dioxide and oxygen, dissipation of surplus heat and temperature control,
and humidity control [5].
1.1. Parameters of Natural Ventilation
Parameters of natural ventilation require correct roof slope design and control of the
ventilation opening area to the air exchange demand. Characteristics for air exchange are
ventilation rate (VE) and air exchange number (N) where:
Equation 1: Equation of ventilation rate [1, eq. (9.1)].
VV (m³/h): ventilation flow rate
AG (m²): greenhouse flow area
Equation 2: Equation of exchange number [5, eq. (9.2)].
VG (m³): greenhouse volume
1.2. The Ventilation Opening Area
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To define ventilation rate and exchange number, it is necessary to calculate ventilation
flow rate. It will be done using the Bernoulli equation:
Equation 3: Equation of ventilation flow rate [5, eq. (9.10)].
h (m): vertical distance between the centers of the regions of inflow and outflow
T (°C): temperature difference
Tm(°C): mean outside temperature
VW(m/s): wind speed
CW (-): global wind pressure coefficient
Cd (-): discharge coefficient
To small greenhouses, the average global wind pressure coefficient is 0.11 [8].
Discharge coefficient is a parameter that changes with the flap ventilation dimensions
and angle of opening. So, it can be controlled by ventilation flow rate, ventilation rate and
exchange number controlling this parameter (See figure 1). Discharge coefficient is calculated
based in the equation 4 [5]:
Equation 4: Equation of discharge coefficient [1, eq. (9.11)].
Figure 1: Flat ventilator dimensions [1, Fig. 9.2].
1.3. Roof Ventilation
Many different kinds of configuration and combination to flap vents exist, and change
with wind conditions, size and configuration of the greenhouse. For small greenhouse,
deflectors are used to reach ventilation efficiency and improve air flow in the greenhouse is the
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utilization of deflectors (See figure 2). According to Zabeltitz [5, pp.214], “The use of deflectors
at the continuous roof flap ventilator in the first windward span can improve homogeneity
considerably”.
Figure 2: Deflectors influence in the air flow [5, Fig. 9.29].
2. COOLING
Sometimes even with a adequate ventilation, the plant temperature can reach 10°C
higher the air temperature. Another parameter that can be controlled by cooling system is
humidity. In cases of additional cooling or increasing humidity in greenhouse, the three main
systems are Fan and pad system, Fog system and Spray system [5].
2.1. Fan and Pad System
This system operates by blowing air from outside and sucking it through dry pads, which
must have a large surface (See figure 3). It is a simple and inexpensive system, which does not
require treated water or a special type of material to be used in the pads. A simplified scheme of
the system of pads can be seen in figure 4.
Figure 3: Fan and pad system [1, Fig. 11.1].
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Figure 4: Scheme of pad system [1, Fig. 11.4].
2.2. Fog System
This system consists in watering the crop area with very small droplets. These droplets
must have a small diameter evaporate before crop area. Zabeltitz said that this system do not
requires forced ventilation. Additionally, it distributes uniformly the temperature and the humidity
inside the greenhouse [5].
2.3. Spray Cooling
The fan and pad system has difficulties reaching the required humidity levels in arid and
semi-arid environments. Sometimes the high cost of the water maintenance of fog system
prevents the application. In one of these cases, there is the spray cooling system. This system
can be added to pad cooling system (See figure 5), and does not require high quality of water
neither high pressure to work. The nozzles diameters are around 3mm and the pressure of
work, 3bar [5].
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Figure 5: Spray cooling system added to pad system [5, Fig. 11.35].
3. HEATING
In cases of low temperature environment it is necessary to have an efficient heating
system.This system is important to reach a high yield with quality and healthy development of
the plants in the greenhouses. It also helps in the humidity control and diseases infestation.
Crops grow faster and healthier with heating. Otherwise, it is an expensive system. So,
the yield of greenhouse must rise with the heating system, but all the investment must be
economically justifiable [5].
3.1. Heat Requirement
To estimate the heating is necessary analyze crop requirements, greenhouse
characteristics and climate conditions. According to Zabeltitz, to calculate the heat requirement
is necessary use the following equation [1, pp.286]:
Equation 5: Equation of heat requirement [5, eq. (12.1)].
u (W/m²K): overall heat transfer coefficient
Ac (m²): surface of greenhouse cover
Ag (m²): greenhouse floor area
tid (K): design inside temperature (depends of the crop requirement)
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tod (K): design outside temperature
To define the overall heat transfer coefficient two different tables can be used. In table 1
the coefficient depends on the cladding material of the greenhouse. In table 2 it changes with
the heating system installed [5].
Table 1: Overall heat transfer coefficient for cladding materials [1, Tab. 12.1].
Table 2: Overall heat transfer coefficient for heating system [5, Tab. 12.2].
To calculate the total required energy (W) is necessary multiply the heat requirement (q)
and the greenhouse surface area (Ag).
3.2. Energy Source and Heat Distribution
As source of energy to heating system in greenhouses the main used are geothermal
energy, solar energy, waste heat from industry and combustion of fossil, wood, biomass, fuels
and coal [5, pp.290]. Distribution can be made with directly fired air heater or through warm
water from boiler system.
3.3. Solar Greenhouses System
In general, solar greenhouses use a heating system that storage heat from day and use
it during the night. It has a large quantity of storage medium and configuration. Collector,
storage and distribution system are the main components of a greenhouse solar system.
The collectors convert solar radiation into energy to heat a medium. Concentrating
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collectors and flat-plates collectors are directly water heater very frequently used.There is also
the possibility to use the solar radiation as energy to solar panels, and apply this energy in a
different heat system. Water and rocks are the most common storage materials. The heat can
also be stored in the soil in phase change materials. The storage capacity must be designed for
2-3 nights.
Energy collected and converted to heat in a medium storage must be efficiently
transferred during the night. During the design of heat transfers is important to consider the
temperature difference, and that usually the water will not be in high a temperature. It creates
the necessity to use big heat transfer areas [7].
As an example, a big and complex system of solar greenhouse has aquifer, heat
exchange, heat pump and boiler. The cooling system net is based in a heat exchange that gets
cold water and warms it using energy available in the greenhouse. The heating system net uses
a boiler and heat pump in the heat water delivery. Additionally, there is a second heat system
net with a condenser that uses the flue gas of the boiler [6].
IV.
Power Management (JLS)
Much research and development has been done to implement homes with modern
green technology. There is much to consider when designing the power management layout. A
Home Automation system published in Energy Procedia’s 6th volume tackles energy control &
power consumption in a very organized, strategic manner.
Household appliances can be linked via communication network to allow for controlled
interactions. Appliances are fit into 3 separate categories: end-user services, which produce
direct comfort to the user by means of heat, cooking, or washing services, Intermediate services
that manage energy storage via electrochemical batteries, and support services, used to
produce the power to the intermediate and end-user services. Fuel cell base generators,
photovoltaic power suppliers, and grid supplies belong to the support services class. Services
can be considered permanent if the energy consumption or production covers the whole time
range of the energy assignment, like heating the household. Temporary services have a
duration of desired time length, such as a cooking or washing device.
Variables of predicted events and costs can be anticipated in a power management
system. Reactions to actual requests and environmental conditions must be controlled in each
individual energy service. Predictions must be modifiable to meet the inhabitant’s needs,
otherwise they will be constraints to decision variables. Non-predictable services appear as
disturbances in the system.
Comfort, whether to human or plant, is one of the most important aspects to consider.
Comfort is not universal, and there are often compromises in comfort while satisfying
technological constraints of equipment. A power profile is put into place to determine the power
consumed and produced over time to a specific inhabitant’s comfort needs. Characteristic
variables depend on the service operation in time, which directly affects a ‘satisfaction function’.
The difference between actual time and required end time are factored into the satisfaction
function to lead to a behavioral model of the continuous changes in the service activity [9].
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Energy storage has improved significantly over the years, but hasn’t caught up to the
technological growth of microprocessors, memory storage, and sensor application development.
Ambient power sources can assist as back-up batteries to minimize the maintenance and
replacement of storage devices.
A wealth of energy harvesting methods was provided in the article. Traditional methods
were mentioned, such as solar and wind use. A few innovative means were discussed. Human
power can be implemented in a smart home along side with traditional means of power. Motion
of doors and drawers can be translated to rotating motion to drive small generators. Vibrations
from walking on the floor can be converted to electricity via piezoelectric sensors. Water flow
throughout the household can drive a small generator to provide electricity as well. These
unique ways of harvesting energy can be implemented in various different applications[10].
V.
Control Unit (BD)
The control unit is one of the most important components in greenhouse automation. It is
the brain of the system. Data such as temperature and humidity is read from various sensors
and adjustments are made (with actuators) depending on a set of user parameters. However,
there are many different controller implementations that can be either costly or inefficient. The
following section will detail various state of the art control units in modern greenhouse
automation, and detail a few implementations based their respective requirements.
In 2011, Domingo Gomez-Melendez [11] published a research paper detailing a control
unit that utilizes fuzzy logic through the use of a Field Programmable Gate Array (FPGA) along
with a personal computer. “Fuzzy logic provides a methodology to represent, manipulate, and
implement heuristic knowledge to control a system”. This system presents a method in which
water and nutrient control can be implemented on a highly precise scale – factors that are vital
to a plant’s health. Gomez-Melendez referred to several failed in controlling a plant’s
environment. One of these attempts used a pulse modulated pump which kept the flow of water
at a constant set-point via feedback causing a disturbance to the plants growth, as nutrient
levels were not considered. Additionally, this implementation was not driven by a processor, but
rather a simplistic sensor feedback system and, therefore, was highly limited.
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Fig.1
Interaction Between Modules [9]
Through the use of an FPGA, designs are cost-effective and can be configured in a way
specific to a particular plant’s requirements. Gomez-Melendez’s proposed control system
features two main modules: a climate module and a nutrition module (see figure 1). The climate
module is based on a personal computer and includes control algorithms developed in the C
programming language. Climate variables such as temperature and humidity are fed into the
system which drives the actuators, and parameters are set by the user to configure the climate
to accommodate the plant’s needs. This system works alongside the nutrition module (an
FPGA) which handles its respective variables such as pH, flow rate, and nutrition distribution.
An FPGA can manage parallel processing, which can reliably control various precision tasks
simultaneously and reliably. “This allows us to free the PC of this task and leaves the
computational power to other more demanding tasks” [11].
K. Rangan [12] proposes another implementation by use of a PIC microcontroller,
specifically the 16F877A chip (see figure 2). With the intended goal of being able to constantly
monitor a distant greenhouse wirelessly through a Global System for Mobile Communications
(GSM) module. Parameters such as temperature, humidity, water pH level, light intensity and
soil moisture are converted into a digital format via an analog-to-digital converter, which is built
into the 16F877A. In order to take make sense of the sensors readings, assembly language
code was written to identify the set parameters. Assembly code was also used to perform digital
signal processing operations, display data on an LCD screen, and send messages to a GSM
receiver.
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Fig. 2
The 16F877A Microcontroller [10]
Similarly, Andri Nugroho [13] and a group of graduate students developed a system
based on the Arduino microcontroller, a widely used and relatively easy platform to program.
This system is divided into two subsystems: local and global (see figure 3). The local system is
defined by all of its components (arduino, sensors, actuators) that are working directly with the
plants. The global system, which consists of a server and various peripherals, is configured with
remote access to the local system, allowing for a user to either manually control the Arduino
where it stands or have it remotely accessible.
The Arduino processes all of the incoming data such as averaging, calibrating, and
smoothing, while also performing data transfer and remote configuration. The board features
analog and digital inputs which receives data from sensors, and drives the actuators, relay
modules and pump connectors accordingly. The Arduino stores data on an SD card, as well as
a configuration file containing an IP and network address, thereby allowing for remote real time
monitoring and control of the system.
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Fig. 3
Arduino Controlled System[11]
Each of these three control unit configurations has advantages and disadvantages.
While Gomez-Melendez’s method can control the environment on a high precision scale, the
inclusion of a PC in addition to an FPGA can be rather costly. Rangan’s proposal to use the
16F877A IC is economically a feasible choice, however writing assembly code for each of the
systems processes could be tedious and inefficient. Nugroho’s use of the Arduino board as the
control unit is practical and affordable, but could pose limitations on computational power and
controllable peripherals. These types of implementations will be considered in the preliminary
designs.
VI.
Conclusion
Overall, the research contributed to new knowledge that can be applied to the smart
greenhouse project at hand. Plant growth, power management, environmental control methods,
and control units are all broad subsystems that tie the project together. With help from a vast
amount of publications from scientists around the globe, the greenhouse should achieve high
productivity, low power, & high efficiency.
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Basis of Design (CLC)
All documents associated with the engineering of S13-41SGRN's Smart Greenhouse can be
found below.
Request for Proposal (RFP)
February 5, 2013
Block Diagram
March 19th
Project Specifications
April 3, 2013
Proposal for Project
April 8, 2013
Description of What is to be Built (JLS)
The proposed smart greenhouse will implement an automated plant growth monitoring
system using the Arduino microcontroller. This microcontroller will employ a user interface to
observe key variables for plant growth by simple means. The variables can be autonomously or
manually corrected, if one or multiple variables are outside the desired range for optimal
growing conditions. Temperature conditions may be manipulated by use of heat tape and
cooling fans. Lighting conditions may be manipulated by use of a timer. Soil moisture can be
manipulated by increased lighting situations or implementation of a water sprinkler system. The
user may also concurrently choose to monitor and assign power sources being used in the
smart greenhouse, being from main utility lines or an alternative energy source. Ability to
connect and monitor a battery bank will also be available to the user. The available power from
each source will be detected and relay this information to the Arduino. The design of the smart
house control unit will be displayed by growing 12 carnivorous plants autonomously in a 2’x2’x2’
controlled enclosure over a period of time. Sensor data will be displayed on the control unit to
keep the user up to date on real time conditions.
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List of Deliverables (CLC & JLS)
●
●
●
●
●
●
●
●
Functioning Prototype Greenhouse: The end product will be able to do all tasks outlined
in the executive summary. There are no promises made for aesthetics.
Engineering Drawing of the Final Structure
Block diagram of Subsystems
Wiring Diagrams: Power System and Control System
Source Code
Technical Manual: Provides information on using the User Interface of the system only.
Analysis and Experiments Report
Cost Analysis: for build only
Analysis and Experiments (CLC)
1
2
3
4
5
6
7
8
9
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Regulate and switch between energy sources automatically and manually
Sense and control humidity in the range of 60-90%
Monitor and control temperature in the range of 60°F-85°F
Monitor and control soil moisture in the range of 10-45%
Ability to control light in the range of 0-33,000 lumens
Light needs to be able to withstand “on” time of 14 hr/day max
12 plants survive over a period of 4 weeks
Proper distribution and recycling of water
Water content monitoring (pH)
Acrylic enclosure 2 feet drop test
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Specifications (BD,JLS,GRS)
Main Properties
Dimensions: 3’ X 2’ X 2’
Number of Plants Sustainable: 12
Total Power Consumption: 125 watts per hour
Plant Species: Tropical/Carnivorous
Sensor Operating Ranges
Humidity/Temperature Sensor
Humidity: 0-100% RH [(+-)2% RH]
Temperature: -40 - 80 C [(+- )5 C]
Power: 3.3 or 6V/1 - 1.5mA (40-50uA standby)
Moisture Sensor
Values:
1. 0-300: Dry soil
2. 300-700: Humid soil
3. 700-950: Submersed
Power: 3.3V or 5V/35mA
Light Sensor
Bandwidth/Reaction Time: 50Hz
Min Light Level: 1 lux
Max Light Level @ 5V: 1000 lux
Max Light Level @ 3.3V: 660 lux
Power: 3.3 or 5V/2mA
Microcontroller
Chip: ATmega328
Operating Voltage: 5V
DC Current per I/O pin: 40mA
DC Current for 3.3V pin: 50mA
Input Voltage(recommended): 7-12V
Input Voltage(limits): 6-20V
Digital I/O pins: 14
Analog Input pins: 6
Flash Memory: 32KB
SRAM: 2KB
EEPROM: 1KB
Clock Speed: 16MHz
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Wireless Connectivity
Operating Voltage: 5V
Connection: 802.11b/g networks
Encryption Types: WEP, WPA2
Ports: SPI
Memory: MicroSD slot
Heating/Cooling
Heat Tape
Dimensions: 12” x 11” x 0.012”
Energy Required: 20 W/ft
Max Temperature: 35°C
Fan
Dimension: 4.72”
Max Angular Velocity: 2000RPM
Acoustic Intensity: 29.28 dBA
Watering
Water Pump
Max Head: 28”
Volumetric Flow: 100 gph
Energy Required: 3.5 W
Air Pump
Water Storage: 1-10 gallons
Volumetric Flow: 50 liters/hr
Energy Required: 3.5 W
Additional Components
T12 Fluorescent Light
Length: 2’
Light Intensity: 875 Lumens
Lifespan: 20,000 Hours
Power Consumption: 20 Watts
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Block Diagram (BD,JLS,CLC)
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Subsystems
Control Subsystem (BD)
Arduino
The Arduino Uno microcontroller will allow us to interact with the environment within the
system. It consists of an ATmega8U2 surfaced mounted chip which can be programmed with
Arduinos integrated development environment. The main purpose of this microcontroller is to
control aspects of the environment via (input/output) I/O ports. This can be accommodated with
the use of a PID algorithm library included in the Arduino IDE. The Arduino includes six analog
inputs that receive data from sensors, and 14 digital I/O ports that will drive our environmental
control actuators(light, water pumps, fans). All of our input sensor feedback will be in the form of
an analog signal, and the actuators can be driven with digital output signals (refer to
CPU/Sensor block diagram and flow charts below).
Temperature/Humidity Sensor
We have chosen a temperature and humidity sensor package, which responds to
variations in these two variables. The package converts input from the physical world and will
pass signals into the Arduino. This sensor will emit two signals proportional to the temperature
and humidity, and will have to be calibrated upon installation. These will be placed in two
different locations within the enclosure to accurately determine their respective values. Below is
a basic control flow chart detailing how this sensor will be used in conjunction with the PID
algorithm.
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Moisture Sensor
This sensor will be placed in the soil of our chosen plants, and will remain above the
surface to allow for easy relocation. Two probes are used to determine resistance between each
probe, and emits a voltage based on the resistance. Higher water content reduces the
resistance, and lower water content increases the resistance.This module outputs a value
proportional to the water content. This range is between 0 and 950 arbitrary units where 950 is
equivalent to the device being submerged. The flowchart below follows a similar algorithm as
above.
Light Sensor
The light sensor will be used to determine whether outside light is enough to sustain the
plant, relaxing frequent usage of the internal light source. It outputs an analog signal at 50Hz,
and operates at a range between 1 to 1000 lux using a 5 volt configuration. A low power mode
can be used reducing the range from 1 and 660 lux operating at 3.3 volts.
Heating, Cooling, & Watering Subsystems (GRS)
Heating
The heating system will be based in heat tapes located at the bottom of the enclosure.
This devices were chosen due its simplicity to instal and control and the fast warming produced.
The heat tapes do not require big investment and work well in the high humidity environment.
The heat tapes are sealed in polyurethane and will work in 35ºC as maximum temperature. Due
the high power consumption of this system (20W/ft), it will be controlled by sensors to be used
just during a specific necessity.
Cooling
The cooling of the small greenhouse will be made by two 120mm fan, both located in the
top of the enclosure. Humidity as one of most important parameters in the carnivorous plants
cultivation is quickly affected by fan operation. While the cooling system is working, to avoid the
decrease of humidity, the watering system will work together to maintain the greenhouse
specification. The actuation and RPM of the fans, and the watering system as supply to the
humidity environment will be controlled by sensors.
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Watering
Considering that gravity feed will add handling difficulty due the high gravity center, and
it is considered dangerous because all electrical components would be under the water storage,
the Smart Greenhouse watering system will use water pump. It will be a 3.5W water pump with
100 gph of flow capacity. The water pumped will be distributed to the lines and to the drip
irrigation nozzles through an orbit manifold. As a support to a best quality of the watering
system the water will be oxygenized. To oxygenate the water will be used a 3.5W air pump and
air stones, that help in the air circulation in the water reservoir.
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Power Subsystem (JLS)
Utility power as well as alternative sources will power the smart greenhouse circuitry and
manual devices used to monitor and tend to plants’ needs. The incoming power sources will be
monitored using a sensing circuit to allow the user to be aware of resources available.
Monitoring will also serve as protection for all electrical components. A clamped emitter type
unijunction zener sensing circuit will be implemented with the power sources in line with battery
storage. This circuit is useful for monitoring power as well as allowing for safe battery charging.
The circuit will function and charge if the voltage is below a specified level. Otherwise, anything
above the critical clamp point will cause the circuit not to function.
Different components in the smart greenhouse power subsystem will require a voltage
regulator to sensitively adjust to certain requirements of the Arduino, each sensing component,
and all systems associated with the control of the immediate environment inside the smart
greenhouse. Fans, heat tape, the watering pump, the air pump, and fluorescent lighting all
require different operating voltages as well [14].
The assumed power consumption is 125 watts, but this can be reduced by the sampling
time duration and frequency of use of each sensor used in the smart greenhouse. Not all
sensory components will be sampling 24 hours a day. Some sensors will be put into a “sleep
mode” or a “lower power mode” to cut power consumption to under 100 watts. The user may
choose to set the control unit on an autonomous power mode, searching for the most efficient
source to give means to plant growth, or the user may choose to manually set these sources
his/her self.
User Interface (CLC)
Internet
The primary interface for the user to access and control data for the greenhouse will be
through a web browser. This was chosen because nearly everyone has at least one device that
uses a web browser, whether it is a home computer, tablet, or smartphone a web browser
controlled system is a convenient way to allows a user to access the greenhouse from
anywhere in the world. This project will not delve into the specifics of server creation or script
writing because it is beyond the scope of the project. With that said, the browser control system
needs to be simple, clean, and be able to display data in a meaningful way. This will be
accomplished by displaying the most important information directly on the home screen, giving
the user a quick look at what is happening in their garden right at that moment. The user will
also be able to control the most vital variables in their greenhouse from the same screen.
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Control Panel
The secondary mode of interface for the user interface would be an on unit control
panel. This panel would have a large screen with easy to read font, only a few buttons to
change and select menus or variables to avoid confusion, and an easily navigable GUI. The
purpose of this secondary interface is for those users who do not have access to the internet or
for those who simply don’t want to have to walk back inside to change a variable but instead can
look at the garden in person, read the values, and make decisions accordingly.
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References
[1] H.S. Paris and J. Janick “What the Roman emperor Tiberius grew in his greenhouses”
Internet: http://www.hort.purdue.edu/newcrop/2_13_Janick.pdf [April 1 2013].
[2] “Planning and Building a Greenhouse” Internet:
http://www.wvu.edu/~agexten/hortcult/greenhou/building.htm [April 2 2013].
[3]John Brittnacher*. “Growing Nepenthes”
Internet:http://www.carnivorousplants.org/howto/GrowingGuides/Nepenthes.php
[April. 1, 2013].
[4] Aaron Ellison, Nicholas Gotelli, J. Stephen Brewer, D. Liane Cochran-Stafira, Jamie Kneitel,
Thomas Miller, Anne Worley, and Regino Zamora “The Evolutionary Ecology of Carnivorous
Plants” Internet:http://www.uvm.edu/~ngotelli/manuscriptpdfs/AER2003.pdf, [April 2, 2013].
[5] Zabeltitz, C. von. Integrated greenhouse systems for mild climates climate conditions,
design, construction, maintenance, climate control. Berlin, Germany: Springer, 2011.
[6] Straten, G. van, and Willigenburg, G. van, and Henten, E. van, and Ooteghem, R. van.
Optimal control of greenhouse cultivation. Boca Raton, FL : CRC Press, 2011.
[7] Verlodt, H., and Mougou, A., & (Ed.). International Symposium on Simple Ventilation and
Heating Methods for Greenhouses in Mild Winter Climates : Djerba, Tozeur, Tunisia, February
28-March 6, 1988. Wageningen, Netherlands : International Society for Horticultural
Science,1988.
[8] Bailey, B.J. Wind driven leeward ventilation in a large greenhouse. Retrieved from
http://www.actahort.org, 2000.
[9] H. Joumaa, S. Ploix, S. Abras, G. De Oliveria, “Energy Procedia,” A MAS integrated into
Home Automation system,..., vol. 6, pp. 786-794, 2011
[10] Dr. F. Yildiz, Dr. D. Fazarro, K. Coogler, “Journal of Industrial Technology,” The Green
Approach: Self-Powered..., vol. 26 #2, April 2010 - June 2010
[11] Rangan, K.; Vigneswaran, T.; , "An Embedded Systems Approach to Monitor Green
House," Recent Advances in Space Technology Services and Climate Change (RSTSCC),
2010 , vol., no., pp.61-65, 13-15 Nov. 2010
doi: 10.1109/RSTSCC.2010.5712800
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[12] Gomez-Melendez, Domingo,. “Fuzzy Irrigation Greenhouse Control System Based on a
Field Programmable Gate Array,” in African Journal of Agricultural Research. vol 6. June 2011,
pp. 2544-2557. Doi: 10.5897/AJAR10.1042
[13] Nugroho, Andri. Okayasu, Takashi. Fushihara, Hajime. “Development of Intelligent Control
System for Greenhouse”. Kyusha University.
[14] “TVS/Zener Device Data On Semiconductor," May 2001, Semiconductor Components
Industries, LLC (SCILLC). [online] Available
http://ae6pm.com/Semidata_books/Motorola/DL150-D.pdf [Accessed: April 30th 2013]
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COMMERCIAL
Budget Justification
The objective when making the budget was to choose quality and simple componentes.
Compared to average greenhouse where prices range from a few hundred to several thousand
dollars, the Smart Greenhouse will not cost more than $500.
The Arduino chosen allows our systen to be affordable and does not create the
necessity to buy other devices to use it. The other components, such as PC fans, heat tapes
and the watering and airing devices were chosen with the same objective: to meet the
requirements and work well in our humidity environment without big investments.
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MANAGEMENT
Organizational Chart (BD)
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Timeline (BD)
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Action Item List (BD)