Design of a Low-Cost Aeroponic Plant Growth Chamber

Design of a Low-Cost
Aeroponic Plant Growth
Chamber
Project plan
May 11-22
Advisor:
Prof. Timothy Bigelow
Team Members:
Zachary Davis
Mohammed Rahim
Christopher Reeve
Daniel Wright
October 12, 2010

Table of Contents
Executive Summary ........................................................................................................................ 3
Problem Statement .......................................................................................................................... 4
System Block Diagram ................................................................................................................... 4
System Description ......................................................................................................................... 4
Chamber Environment ................................................................................................................ 5
Control Environment .................................................................................................................. 5
Sensor & Control Hardware........................................................................................................ 5
Operating Environment ................................................................................................................... 6
Operating Parameters .................................................................................................................. 6
User Interface Description .............................................................................................................. 6
Functional Requirements ................................................................................................................ 6
Non-Functional Requirements ........................................................................................................ 7
Market Survey ................................................................................................................................. 7
End Product & Major Deliverables................................................................................................. 7
Work Plan ....................................................................................................................................... 8
Work Breakdown ........................................................................................................................ 8
Cost ............................................................................................................................................. 8
Schedule ...................................................................................................................................... 9
Risks ............................................................................................................................................ 9
References ..................................................................................................................................... 10
Contact .......................................................................................................................................... 10
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Executive Summary
As humans, our lives necessitate the need for food. This food comes from many sources, one of
them being plants. Since this is important to our very survival, there is a need for research to
produce disease resistant and quicker producing plants. In order to conduct research there needs
to be a controlled environment, which allows a researcher to change different variables in the
growth of a plant to see what effects it has. Many of these controlled environments employ the
use of aeroponics (where the roots of the plant are in air instead of soil or water) to grow the
plants. The use of aeroponics is also undergoing research as a way to grow plants easier in
space. Since aeroponics uses less water than either hydroponics or geoponics this could be
beneficial on extended excursions.
Our goal at the end of our senior design project is to have a low cost controlled plant growth
chamber that utilizes aeroponics. Growth chambers that are currently on the market can cost
nearly $100,000, so a cheaper alternative could greatly enhance research that is being performed.
In order for our chamber to be a serious competitor, we need to have the same types of sensors
offered by the current solution. This means that our chamber will need temperature, humidity,
CO2, and atmospheric pressure sensors. We also must be able to keep a consistent temperature,
provide nutrients to the plants, have a consistent airflow, and be able to give the plants light.
There is also a desire to see what effects sound has on the growth of the plants. Therefore, our
chambers will have speakers in order to try different frequencies on the plants. Beyond this, we
would like to have the ability to control the settings for multiple chambers from one central
location.
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Problem Statement
Many disciplines do research with plants and need a controlled growth environment. Existing
growth chamber solutions available are far too expensive for typical use in research. Our team‟s
task is to design and build an economically feasible controlled environment for the growing and
monitoring of plants using aeroponics. Such a system has many applications in research and
other fields.
System Block Diagram
System Description
The system has three major components. The first is the chamber environment. This is the
physical environment, such as temperature and humidity, which we need to monitor and control.
The second part is the control block. This part is responsible for monitoring and affecting the
chamber environment through sensors and heaters, etc. This consists of a microcontroller and
the application software, not the sensors themselves. The third part of the system is the physical
sensors and other environment modifiers such as heaters, water pumps and lights. This part of
the system provides feedback to the control system on the chamber environment.
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Chamber Environment
The physical attributes of the growing chamber, hereafter referred to as „the chamber‟, is where
the plants grow. There are a number of factors that must be carefully monitored and some that
must be controlled. According to the International Committee for Controlled Environments, the
minimum measuring and reporting guidelines are:
Radiation
Temperature
Atmospheric Moisture
Carbon Dioxide
Air Velocity
Watering
pH
Electrical Conductivity
Substrate
Nutrition
Chamber dimensions
For our project, it will not be necessary to monitor or report substrate, as aeroponic growing uses
no substrate. Of the remaining parameters, only the Temperature, Radiation, and Air Velocity
will be actively changeable with our setup; the rest will simply need to be monitored and
reported.
The chamber itself will consist of a housing large enough for the plants to remain suspended
through their growth cycle, as well as all the hardware required to vent, water, light, heat/cool,
and drain the plants growing inside.
Control Environment
The control environment for the system will consist of a microcontroller interfaced to the various
sensors that will be responsible for reporting the current conditions and activating the active
elements (heater, pump, light, etc.). The microcontroller will be able to remotely communicate
with a separate computer that will serve as a database and web server. With the computer, lab
technicians will be able to monitor the current state and activate or schedule active element
events. This system consists of both hardware and software elements.
Sensor & Control Hardware
A wide array of sensors is needed to properly monitor all the required parameters. In addition,
the chamber must provide a way to heat, vent, light, and water the plants inside. The sensors
must be accurate and able to withstand the humid environment of the chamber. The light, water
pump, and ventilation fans must be easily controllable with a microcontroller. Each sensor is a
discreet component, and is connected to the control system by wires.
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Operating Environment
The operating environment for our project will consist of the physical environment that the
growth chamber is placed in. It does not consist of the environment inside the growth chamber,
thought it may effect it. The growth chamber gets its air from the outside environment, so
conditions such as temperature and humidity do affect it to some degree.
Operating Parameters
The growth chamber is designed to be placed in a relatively stable lab setting. The chamber does
have some facilities to change its internal temperature and humidity, but these are not effective
outside a certain range. This range is determined by the insulation factor of the chamber walls,
but in general should be limited to between 50 and 90 degrees Fahrenheit. There are many
reasons for this limitation, the most important of which is that the plumbing and mineral water
tank are not insulated. Freezing temperatures would render the irrigation system inoperable, and
possibly damaged. The exterior of the chamber is not water proof, so it should not be placed in a
location that is very moist or where there is a possibility of rain.
Some plant growth chambers on the market today are of a chamber-in-a-chamber design. Our
chamber does not have this requirement, it is self sufficient as long as the operating environment
is kept to the reasonable levels stated above.
The aeroponics growth chamber requires a stable, moderate, and dry environment in which to
grow plants. The environment is free to fluctuate in a normal fashion, within the operating
parameters, and the chamber will be able to maintain a reasonable environment for growing
plants.
User Interface Description
The server will host an ASP.NET website to enable remote control of any number of growth
chambers connected to the server. A user will be able to control many settings including, but not
limited to, temperature control, lighting on/off timing, speakers on/off timing, and possibly the
frequency of which the nutrient solution is sprayed. There will also be many aspects of the
chamber that will be monitored, stored, tracked, and made available for viewing. This would
include, but is also not limited to, the monitoring of the temperature, humidity level, timing of
the pump (nutrient spray), CO2 & O2 concentration, and when the speakers are on. These things
will be periodically stored in a SQL database. The website will be secure, requiring a user name
and password to enter. Only accounts given administrator privileges will be allowed to change
any growth chamber settings.
Functional Requirements
1) To build a fully-functional, low-cost aeroponics growth chamber
2) To keep the roots of the plants in the dark, as required for aeroponics growth chambers
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3) To prepare the correct Hoagland solution (Type I) to provide nutrients to the plant in an
aeroponics setting
4) To have the capability to administer sound (audible and ultrasound) to the plants inside the
growth chamber to investigate its effects (if any)
5) To have the capability to control and monitor various environmental parameters from a
remote server. The parameters that need to be controlled are:
a) Radiation (Light)
b) Temperature
c) Carbon Dioxide (CO2)
d) Air velocity
e) Watering
f) Sound
Non-Functional Requirements
1) To monitor, measure, and report the following parameters as required by North Central
Extension & Research Activity–101 (NCERA-101):
a) Atmospheric pressure inside the chamber (Water vapor pressure deficit (VPD) or Relative
Humidity (RH))
b) pH and Electrical Conductivity (EC) of the nutrient solution
c) Substrate (this will be air for our aeroponic growth chamber)
d) Nutrition (Hoagland solution Type I)
e) Chamber properties:
i) Specifications (floor area)
ii) Barrier beneath lamps (whether present and its composition)
iii) Air flow (whether up, down or horizontal)
2) To build a visually-appealing web interface to monitor and control various physical
parameters (as indicated above) inside the growth chamber.
Market Survey
In order to get a better understanding of aeroponics and plant growth chamber our group had a
meeting with Dr. Richard Gladon from the Department of Horticulture here at Iowa State
University. He informed us of what parameters needed to be monitored in order to have research
be considered valid. This is what determined the types of sensors that we will need and how we
will need to report things to the user. He also suggested that we design a growth chamber that
can accommodate tomatoes. These are the simplest to grow and are common for an initial study.
End Product & Major Deliverables
At the end of our project we expect to have these documents up to date and delivered:
Project Plan
Design Document
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Final Report
Project Poster
For the end project we will have two aeroponics chambers. These chambers will be able to keep
a consistent temperature, CO2 level, humidity level, and atmospheric pressure. There will also
be the ability to have an audible tone played and a light turned on and off. All of these can then
be user defined. The user will be able to log onto a web server in order to change the settings of
any given chamber. The specific chamber will then have its status changed via a Bluetooth link
to the web server.
Work Plan
Work Breakdown
This table explains the estimated amount of hours that will be spent, by each member, on the
major portions for our project
Project Plan Design Implement Test Total
Chris Reeve 10 30 100 30 170
Zachary Davis 10 30 100 30 170
Mohammed
Rahim
10 30 100 30 170
Daniel Wright 10 30 100 30 170
Cost
Below is a table showing the cost breakdown
Item Cost
Sensors ($40 x 2) $80.00
Microcontroller ($20 x 2) $40.00
Microcontroller Board ($50 x 2) $100.00
Chamber Parts ($50 x 2) $100.00
Chemicals $50.00
Web Server $50.00
Total $420.00
Labor ($20/hour) $13,600.00
Fictional Cost $14,020.00
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Real Cost $420.00
Schedule
Risks
1. Some of the existing components do not work
Problem: If some of the components that are already around do not work then we will
need to buy more than we expected. Since we only have a limited budget this could
cause us to go over budget.
Resolution: If there is still money left then we can probably simply buy the needed parts,
if not then we will need to find money elsewhere. When first buying things we need to
leave money for a problem like this.
2. Exceeding the project budget
Problem: There are many things that we would like to include, but only have a limited
budget to do it on. This means that we might not be able to afford everything that we
want.
Resolution: We would need to reconsider some of our desires. One would be instead of
having a wireless link from the chambers to the web server we might have to have a
wired one. Also, we might be able to only do one chamber instead of two.
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References
Langhans,Roberts and Tibbitts,Theodore, eds. “Plant Growth Chamber Handbook.” Ames: Iowa
State University, 1997.
Contact
Advisor
Timothy Bigelow
2113 Coover Hall
Ames, IA 50011
Phone: 515-294-4177
Email: bigelow@iastate.edu
Students
Zachary Davis
4700 Mortensen Rd
Ames IA, 50014
Phone: 641-233-7209
Email: zdavkeos@iastate.edu
Mohammed Rahim
140 University Vlg Apt F
Ames, IA 50010
Phone: 515-572-4719
Email: mrahim07@iastate.edu
Christopher Reeve
530 Welch Ave Apt 1
Ames, IA 50014
Phone: 641-203-2429
Email: creeve@iastate.edu
Daniel Wright
2511 Bristol Drive #201
Ames, IA 50010
Phone: 515-401-2429
Email: dwwright@iastate.edu
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