Autonomous Robotic Fish to detect Harmful Algae Blooms (HABS)
PREPROPOSAL:
Design Team:4 Team Facilitator: Dean Aslam
Team members: Taha Tareen, Jamie Jacobs, Stephen Garrett, Woodard Williams Eric
Jackson, Carl Coppola, Robert Morris, Allen Eyler
Date: 02/4/09
EXECUTIVE SUMMARY
Aquatic eco-systems are undergoing dramatic changes due to human activities and change in
climate, which results in environmental pollution and affects human wellbeing. The proliferation
of HAB’s is caused by cyanobacteria producing toxins which accumulate rapidly in water
bodies, thus proposing a great danger to our lives. At Michigan State University the goal is to
advance knowledge and transform lives. The purpose of this project gives us the opportunity to
do the same by making the world a healthier place through detecting harmful algae blooms
(HABS) in three-dimensional water bodies.
To achieve the goal the most critical issues surrounding the project are the implementation of
Graphical User Interface (GUI), digital signal controller and the wireless integration. The
following steps are to be taken as the basic requirements of the project. For bacteria detection the
HAB sensor will be interfaced in to the circuit and the GUI will be updated accordingly. An
infrared sensor (IR) will also be implemented for avoiding collisions in water bodies. The
electrical casing inside the fish will be made for locking the circuit inside and is according to the
conceptual design of the robotic fish itself which also has a compass integrated for the direction
movement. Finally demonstrating the fish in the water tank or a lake will provide the results and
ensure success.
The project target is to purify the waters of the world from bacteria through this great
humanitarian invention. To improve the system and make it more reliable a recommended
modification is in the collision detection sensor selection. This recommendation would be to
implement whiskers instead of the IR sensors to avoid collisions. The whiskers would avoid
only large objects or species in water bodies and smaller objects, such as seaweed and lilly pads
would go undetected. This design criterion will give a much more efficient system with an
advanced collision detection operation that would require a larger force to the whiskers and
would make it stop and avoid any large harmful objects.
TABLE OF CONTENTS
Introduction………………………………………………………………...2
Background …………………………………………………………….....2-3
Design Specifications………………………………………………….......3-5
Conceptual Designs……………………………………………………......6-9
Rankings of Conceptual Design……………………………………….......9-10
References…………………………………………………………………10
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INTRODUCTION:
With the environment constantly changing due to human abuse of the planet, scientists
are consistently faced with the challenge of coming up with new, more effective methods of
understanding/predicting an ecosystem’s response time to global change. One of the more
severe concerns of the planet is the aquatic ecosystems. As a result of different contaminants
and toxins already disturbing our water, proper functionality of ecosystems and human welfare
are dangerously at risk. More specifically, the abundance of harmful algal blooms (HABs) is
becoming a more critical issue. In freshwater, HABs are caused by cyanobacteria producing
potent toxins. These toxins can negatively impact water supplies and accumulate in fish. In the
purpose of this project is to continue the development of an autonomous robotic fish that can
detect harmful blooms. Consequently, this specific research should hopefully be able to open the
door for better ways of monitoring the various water bodies of the Earth, and in the future, better
ways of understanding ecosystem behavior.
BACKGROUND:
In 2005, the robotic fish project was initiated by the Smart Microsystems Laboratory (SML) on
the campus of Michigan State University. The mission of SML is to enable smarter, smaller,
integrated systems by merging advanced modeling, control and design methodologies with novel
materials and fabrication processes. The purpose of this task was to build small mobile platforms
to be used in aquatic wireless sensor networks. Since August of 2005, SML has developed three
generations of robotic fish.
The first design, G1, was developed by a senior design team. It was equipped with a
microcontroller and wireless communication and was controlled through graphical user interface.
The outer shell was a commercially available toy fish, modified to accommodate the circuitry.
In August 2006, the G1 greatly improved on the specific problems such as space optimization
and waterproofing of the circuit. The second version of the G1 was smaller size and weight.
Additionally, it was equipped with a temperature sensor which allowed for a more life like, true
mobile sensing capabilities. However, like the first model, the circuit was still confined to a toy
fish shell. In 2007, a new prototype was introduced with ranging abilities and a custom built
outer shell. New methods were also used to for better waterproofing the circuit. In 2008, the
robotic fish was upgraded once again. This time the main focus of the upgrade consisted of
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computation capabilities. Instead of using a microcontroller, a digital signal controller was used
which allowed for the implementation of two more complex ranging algorithms. Also, this
design included an onboard battery power source which allowed for increased hours of run time.
Throughout each generation of the robotic fish, the most significant prototype constraints
included: the design of the outer shell to keep the circuit completely dry, mobility, and using the
proper applications to transform the robotic fish from a mere fixed sensing circuit to a mobile
robot.
DESIGN SPECIFICATIONS:
The objective of this project is to build an autonomous robotic fish that is capable of three
dimensional diving, wireless feedback controls, and detecting harmful algae blooms in diverse
aquatic ecosystems. The product will exist as a prototype for developing a group of sensor
carrying robotic fish that will monitor lakes and possibly help prevent deteriorating water
quality. To fulfill the objective the following constraints, ordered in terms of importance to the
customer, must be satisfied:
1.) The robotic fish must be interfaced with a small sensor that can detect harmful algae
blooms in water bodies.
The desirability of this aspect of the design is very high. The sensor detects
cyanobacterial (algae) pigments that emit fluorescence when excited by certain light
waves. The sensor would then record the concentration of algae and send information
remotely to a laptop on shore.
2.) The graphical user interface (GUI), digital signal controller, and circuit board must be
updated.
Currently the GUI, digital signal controller, and circuit board are designed for a fish that
moves in two dimensions. For the robotic fish to work correctly, all components of the
phase one, two dimensional fish must be upgraded and interfaced with sensors.
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3.) The robotic fish should be equipped with wireless feedback controls.
The feedback control will allow the team to precisely know which direction the robotic
fish is heading. This will be accomplished by interfacing the fish with a compass or
magnetometer.
4.) The robotic fish must be interfaced with a sensor that can detect approaching objects.
This sensor will protect the fish from crashing into rigid objects and becoming damaged.
The sensor will detect an object and an event will occur in the circuitry that will allow the
fish to turn and avoid the obstacle.
5.) The robotic fish should possess a versatile packaging scheme and a suitable body shape.
With the help of team members with a mechanical engineering background, an upgraded
robotic fish body and packaging can possibly enhance the state of the art of robotic fish.
The robotic fish should resemble the appearance of an actual fish and the encasing must
be water proof so that the electrical components will be protected.
6.) The robotic fish should be capable of swimming 1.5 cm/s or faster.
To effectively monitor a lake within the battery life of the robot, the fish should be able to
swim 1.5 cm/s. An increased speed will also enable the sensor to detect more harmful
algae.
7.) The team must demonstrate the operation of the mobile sensor platform (including
wireless communication and GUI) in a water tank.
Demonstration of the robotic fish in a tank will prove the capability of the project to
move to an actual lake, if environmental conditions allow. Also, the operation of the fish
in water will be tested.
The autonomous robotic fish will be designed based on the preceding criteria. To determine the
desirability of a design, the following set of criteria has been developed:
1.) Function
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This parameter determines if the design follows the mandatory constraints identified
above. It is the first and most important aspect of the design.
2.) Size
The robotic fish body must be large enough to hold the HAB sensor and the other
electrical components. Also, what must be considered is that if the fish is large in size
and light in weight it will displace more water and have a difficult time submerging.
3.) Weight
The weight of the robotic fish design can affect ascension or descension in the water.
To descend the fish must weigh more than the water it is displacing. To ascend the
fish must be more buoyant than the water. A design with the ability to control weight
while in the water is preferable.
4.) Energy Consumption
The robotic fish will run on batteries, so monitoring energy consumption is relevant
to a good design. The rate of power consumed directly determines how long the
device can stay in the water and detect harmful algae. A robotic fish that can use less
energy and still be effective in its operation is highly desired.
5.) Reliability
This parameter concerns the ability of the design to perform tasks and operate in a
consistent manner.
6.) Aesthetics
Appearance can have a large impact on marketability. A robotic fish that has a very
close resemblance to a real fish can draw a lot of attention by looks alone.
7.) Delivery Date
A design that is too complicated may not be achievable by the delivery date. Each
design must therefore be rated on its feasibility of completion time.
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CONCEPTUAL DESIGN DESCRIPTIONS
Design one is a fish similar to the body shape of the current robotic fish. The same can be
compared to the body shape of a submarine, see figures 1-3 below. The body would be both
hydrodynamic and fast. The body would be made of Aluminum allow for fast access to the
control circuitry inside of the fish body. The Fish would have one large fin at the bottom that
would work as the main propulsion of the fish. Unlike the current fish, which has one artificial
muscle polymer attached at the tail, this design requires between three and five polymers placed
in a parallel manner on the bottom fin. The polymer would move one at a time, as to not drain
on the battery and would move in a top to bottom fashion. The thought is that the fish would be
able to move faster in a straight direction as well as turn to avoid objects in a faster and more
precise manner. Instead of using IR sensors (as suggested by the sponsor) the idea is to use
“whiskers” as used in the “Boe-Bot,” see figure 4 below. How the whiskers are connected to the
circuitry is also shown below. These whiskers would be attached to the front of the fish to detect
the path to the front of the fish. The advantage to using the whiskers rather than the IR sensors is
to minimize the amount of objects the fish avoids. With the IR sensor the fish would avoid
anything it its path which includes fish, wood, seaweed and lilly pads etc... While some of these
objects obviously need to be avoided, other objects such as seaweed and lilly pads need not be
avoided. The whiskers would allow for this. The whiskers work as a normally open switch.
When there is a large force applied to the whiskers the circuit is completed and the voltage is
dropped to ground. This would stop the fish and allow for a change in direction. The idea that a
fish could get stuck in a location where it cannot move due to an object detected on all sides is
minimized.
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Figure 1
Figure 2
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Figure 3
Figure 4
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Figure 5
RANKINGS OF CONCEPTUAL DESIGNS
HAB
Sensor
5
Collision
Detection
5
Direction
Control
5
Speed
4
Power
Use
4
PWM
in/outs
4
Polymer
quantity
3
Cost Size
3
1
Buoyant
1
Aesthetics
1
1
2
3
4
…
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The conceptual design matrix above lists the testing factors in deciding the proposed design
solution. Per the requirements of the sponsor the most important factors were designated with 5
points. The sponsor requested a robotic fish with a fully integrated HAB sensor, collision
detection capability, directional control using on board compass and a specific speed
requirement. Above all else, these factors must be obtained so they were given the heaviest
weight. Speed was given a rank of a 4 because once it is above the customer cut-off it becomes
an extra rather than an expectation. The factors given a weight of 4 can all be grouped together.
Many of our conceptual designs require the use of more than one polymer. The concern then lies
in the amount of power required to supply to the artificial muscles. The number of PWM inputs
and outputs is then important. Each polymer requires 2 PWM pins. The largest available DSC
has only 8 PWM pins. Less weight has been put on the cost factor because a more reliable and
pleasing design can later be improved to be inexpensive. The group would rather spend more (to
and extent) than jeopardize the quality of the final product. The final categories were all given
the weight of one because they are either linked to another factor in the matrix or are not as
necessary a requirement in the final design.
REFERENCES
Parallax, Inc. Staff. Robotics Version 1.0. Danbury: Parallax, Incorporated, 2004.
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