Table of Contents
Document
Page
Need/Problem and Design Idea Summary
2
Literature and Patent Search Results
4
Marketing Plan
16
User Requirements Document
20
Proposal
22
Design Alternatives
32
Engineering Standards
35
High Level Block Diagram
38
Appendices
Appendix A- Contact Information
40
Appendix B- Major Objectives
41
Appendix C- Gantt Chart
42
1
Need/Problem and Design Idea Summary
After weeks of brainstorming and research, Design Team 5 has narrowed down a plethora
of ideas to two promising ideas. The selection criteria consisted of three factors: feasibility, cost,
and difficulty. To ensure feasibility Team 5 considered each idea’s ability to be implemented in
four months during Senior Design II along with the possible consumer demand and general
profitable attributes of a finished product thereafter. Secondly, Team 5 considered the cost of
each idea by analyzing several design techniques that could be used to realize an idea. Lastly,
the team considered each idea’s level of difficulty to avoid obstruction of work during the design
process.
One idea is a low cost vision aid device for the vision impaired called a virtual walking
stick. It could possibly be implemented as a hands-free cell phone earpiece connected to the
head near the wearer’s eyes. It would detect obstacles depending on the direction of the wearer’s
head location and produce an audible sound to let the wearer know that an obstacle is in the
direction of where the head is pointed. For instance, if the head is pointing forward, the device
would sweep a designated area in front of the wearer employing object sensors used by robots
then beep if an object is detected within a certain distance.
The second idea is a remote control or automatic lawnmower and edger. The
lawnmower/edger would not have to be completely reinvented. Instead, a regular lawnmower
could be modified to be either completely controlled by a human using a remote control device
or partially controlled by a human using an underground magnetic track. The first design
approach would consist of robotic-like controls similar to a remote control vehicle with wheels
or tracks. The second design approach is somewhat more complicated and costly; however, it
lessens the need for direct human control. Both approaches must have strong safety parameters
to guarantee no harm would be done as long as it is operated according to reasonable safety
guidelines.
Team 5 has considered several potential faculty/professional individuals as the team’s
mentor/advisor. Currently, the team is seriously considering Dr. Fred Hudson of UTSA’s
Department of Electrical Engineering as the team’s official mentor/advisor. In addition to Dr.
2
Hudson, the team wishes to seek additional advice from various other professors and
professionals in industry.
3
Literature and Patent Search Results
1.0 Literature Search
TITLE: Optimal bandwidth allocation for bandwidth adaptation in wireless multimedia
networks
SOURCE: Computers and Operations Research, v 30, n 13, November, 2003, p 1917-1929
AUTHORS: Ahn, Koo-Min; Kim, Sehun
ABSTRACT: The concept of bandwidth adaptation which additionally allocates the terminated
bandwidth to ongoing calls is one of the promising methods to reduce the new call blocking and
handoff call dropping probabilities. In this paper, we formulate the bandwidth allocation problem
for the bandwidth adaptation as a binary linear integer program which maximizes the satisfaction
degree of customers. Since this optimization should be performed in real time, we presented a
computationally efficient heuristic algorithm for the problem based on the Lagrangean relaxation
procedure. Our simulation test shows that the algorithm finds a sub-optimal solution within 0.5%
in average from the true optimal solution. The solutions of our scheme show better performance
than other scheme in both handoff call dropping and new call blocking probabilities. Scope and
purpose with the emergence of various multimedia applications, it becomes more important that
wireless networks satisfy quality of service (QoS) requirements. Each base station has a specific
amount of bandwidth to be used within a small geographical area called cell. As the number of
users increases, the amount of bandwidth assigned to a cell becomes insufficient to support the
required number of users. Therefore, wireless networks will employ smaller cells to perform
channel reuse in the cells at specific distance and to accommodate the overall increase in system
capacity. Since employing smaller cells implies higher rate of handoff, the continuous support of
QoS guarantees of multimedia calls poses a major challenge in the wireless networks. Such a
support requires the development of an adaptable network resource management framework. In
this paper, we deal with the multimedia adaptive service where the bandwidth of an ongoing call
can be varied during its lifetime. When an ongoing call is completed or is handed off from a
4
current cell to another, its bandwidth can be reallocated to other ongoing calls. The concept of
this bandwidth adaptation is one of the promising methods to reduce the new call blocking and
handoff call dropping probabilities. If the bandwidth is optimally allocated among all ongoing
calls which need more bandwidth, then the satisfaction grade of the customers can be increased.
We formulate the bandwidth allocation problem for this bandwidth adaptation as a binary linear
integer program which maximizes the satisfaction degree of customers. © 2003 Elsevier Science
Ltd. All rights reserved.
THOUGHTS: As competition for cell-phone companies increase it gives consumers a wider
choice of a low cost cell phone plan, forcing companies to focus their attention on their quality of
service and reliability, so that they may market to a perfectionist generation. Companies using
their cell-phones to place business calls, need reliable service without the chance of a dropped
call, so reworking networks to handle bandwidth is optimal in achieving that goal. This articles’
method of maximizing the satisfaction degree of customers provides a good example on how
cell-phone companies can satisfy more of their customers and provide better reliability. As far as
the format of the paper goes it was overall very well organized and structured with detailed
examples of his methods.
5
TITLE: On the Limits of Steganography
SOURCE: IEEE Journal on Selected Areas in Communications, v 16, n 4, May, 1998, p 474-481
AUTHORS: Ross J. Anderson and Fabien A. P. Petitcolas
ABSTRACT: In this paper, we clarify what steganography is and what it can do. We contrast it
with the related disciplines of cryptography and traffic security, present a unified terminology
agreed at the first international workshop on the subject, and outline a number of approaches—
many of them developed to hide encrypted copyright marks or serial numbers in digital audio or
video. We then present a number of attacks, some new, on such information hiding schemes.
This leads to a discussion of the formidable obstacles that lie in the way of a general theory of
information hiding systems (in the sense that Shannon gave us a general theory of secrecy
systems). However, theoretical considerations lead to ideas of practical value, such as the use of
parity checks to amplify covertness and provide public key steganography. Finally, we show
that public key information hiding systems exist, and are not necessarily constrained to the case
where the warden is passive.
THOUGHTS: Dr. Auguste Kerckhoff put forth the standard cryptological principle when he
said that the encoder must proceed as though the opponent knows the method, but not the key.
Steganography is the science that says the opponent must not realize that there is an encoded
message to be decoded. This article discusses not only the history of steganography, but the
various branches of steganography and the future direction of this science. There are many
different ideas in steganography based on if you want to pass an image or text, do you concern
yourself with security, capacity or robustness, and who is your opponent. I’m not sure if we
would be able to incorporate this into our design project, but it is an interesting science that can
be improved upon.
6
TITLE: Visual Cryptography
SOURCE: Lecture Notes in Computer Science, n 950, Advances in Cryptology EUROCRYPT'94, 1995, p 1
AUTHORS: Naor, M and Shamir, A.
ABSTRACT: In this paper we consider a new type of cryptographic scheme, which can decode
concealed images without any cryptographic computations. The scheme is perfectly secure and
very easy to implement. We extend it into a visual variant of the k out of n secret sharing
problem, in which a dealer provides a transparency to each one of the n users; any k of them can
see the image by stacking their transparencies, but any k-1 of them gain no information about it.
THOUGHTS: From the time of the Greeks, and possibly before them, encoding and decoding of
messages to ensure secrecy in communication has been employed. The level of sophistication in
implementing these methods has evolved over the years and has branched into a field of study,
combining concepts from various disciplines of science with the advent of computing
technologies. This field of study is known as cryptography. Visual cryptography is a type of
cryptographic scheme that enables a user to decode a message using the human visual system. It
divides the message, which can be text or an image, into n images each of which is
indistinguishable from the other. The original message is reconstructed by superimposing k out
of the n images, k < n, on transparencies and projecting them on a screen. The method is very
attractive as it does not employ a sophisticated algorithm to decode the message; the human
visual system is used instead. It is interesting to consider images that can be decomposed into
random noise and at the same time depend on the original message. It is clear that such type of
decomposition will have a sophisticated algorithm for outputting images for higher values of k
and n. In the final section of the paper, the authors talk about decomposing grayscale images by
using novel techniques that will both save computational complexity and time that is quite
interesting, as incorporating a security feature such as this would be fruitful to making a design
aimed towards more complete security.
7
TITLE: Distance measurement of moving objects by frequency modulated laser radar
SOURCE: Optical Engineering, v 40, n 1, January, 2001, p 33-37
AUTHORS: Richard Schneider, Peter Thurmel, and Michael Stockmann
ABSTRACT: Frequency modulated laser radar is an interferometric device that offers for
metrology the possibility to measure absolute distances of the order of several meters with an
accuracy down to 10 µm. This value corresponds to the roughness of many technical surfaces.
Dynamical effects such as movement of the object of interest or scanning of the laser beam can
cause large systematic measurement errors due to the Doppler Effect or time-dependent phase
variations. Especially in industrial environments, a sufficient isolation against vibrations cannot
always be guaranteed. To overcome this problem we develop a setup with two laser diodes that
are simultaneously tuned upward and downward in frequency. After compensation of the
nonlinear tuning characteristics of the tunable laser diodes, the heterodyne signals from both
interferometers are multiplied with each other. By appropriate filtering, the undisturbed
intermediate frequency, which is proportional to the distance, can be evaluated. Experimental
results prove the new concept.
THOUGHTS: Team 5, the Dream Team, found the paper to be comprehensible and informative.
Many of the concepts discussed in the paper are concepts we have had exposure to in our
engineering classes. Such concepts include frequency modulation, phase shifting, sampling
theorem, narrow-band filtering, fast Fourier transforms, Doppler Effect, and analog-to-digital
converting. In addition to recognizing familiar concepts, we learned about new principles such
as the process of linearization of the laser diode, Michelson and Mach-Zehnder type
interferometers, and Rayleigh length of focusing optics. Overall, the group agreed the
information within the paper is useful in that the procedure can be recreated and expanded on
with further investigation.
8
1.1 Focused Literature and Patent Search
Wuertz, Robert M., Benson, Terrance G. 2004. Drive-by-wire lawnmower. United States patent
application 20050050871
DISCUSSION: The inventor has developed a drive-by-wire riding lawn mower. This should
not remotely impact the idea of the group. This invention uses a wire to continuously connect a
microcontroller to a set of wheels on the riding lawn mower. The microcontroller is used to steer
the mower in a prescribed direction. One of the group’s preliminary concepts uses a wire to send
information from a microcontroller to another microcontroller mounted on the lawn mower.
After the information is sent, the wire is removed and the lawn mower is again autonomous.
9
Madhavan, R., Durrant-Whyte, H.F., 2005. Terrain-aided localization of autonomous ground
vehicles. Automation in Construction, 13 (1), 83- 100.
DISCUSSION: The authors of the article discuss a framework developed for localization of
autonomous vehicles. The ability of an autonomous vehicle to determine its position and
orientation with respect to a frame of reference is defined as localization. In order to implement
localization, a collection of sensors are placed in various parts on the vehicle body for
determining artificial landmarks, direction of motion, and speed. The design also incorporates
the use of global positioning system, GPS, used in order to calibrate the steering encoders. Our
design idea, the autonomous lawnmower, can incorporate their approach in determining
localization as it is will be a key factor in determining the versatility of the product. A bearingonly sensor mounted on the highest point of the lawnmower body can used to detect strategically
placed RF strips. The locations of the RF strips have to be known before hand through surveying
the environment. Thus, as the mower moves through the terrain, the information obtained from
the other sensors on speed and orientation along with the readings of the bearing-only sensor
make it feasible to realize a map of the terrain. The map will be constantly updated as the vehicle
moves. Once the initial map has been realized, every movement by the mower after that can
traced on the map using an iterative closed point algorithm, ICP, which calculates the square-root
of Euclidian distance between the two co-ordinates of motion, the starting point and ending point
of motion during that particular time interval and compares it to a pre-determined value to check
if it is less than or equal to it. This, in combination with the extended Kalman filter algorithm,
EKF, which uses a non-linear model, provides an estimation of the vehicles’ orientation. This
process will again refine the map determined with the help of the artificial landmarks. With
every run, provided it is on the same terrain, the mower will be able to navigate through the
terrain better.
10
Angott; Paul G., 2005. Unmanned utility vehicle. United States patent application 20060059880
DISCUSSION: In summary, the inventor developed an unmanned utility vehicle for traversing a
plot of land. The impact of this patent could be fairly significant. The patent specifically covers
an autonomous lawn mower. It also covers the guidance assembly. This is includes laser
navigation system, a radio frequency navigation system, a GPS navigation system, or a camera
navigation system. This will be a patent that our group will possibly need to improve or alter
enough to not infringe on the patent rights.
11
Hartwig, Stephan, Piikivi, Lauri, 2001. Pluggable server module for wireless remote controlling
of devices. United States patent application 20030055909
DISCUSSION: Essentially, the inventor developed a pluggable server module (PMS) for remote
controlling a device. The impact of this patent on our group’s idea of an autonomous lawn
mower is indeterminable at this point in time. This patent specifically discusses the ability to use
the PMS with an autonomous lawn mower, however, our group has yet to decide how exactly the
lawn mower will be controlled. This patent should not hamper the development of an improved
PMS.
12
DEAN TECHNOLOGIES INC., 2006. Programmable lawn mower. U.S. patent application
10/603,572. 2006-09-05.
DISCUSSION: The patent claims the invention is “a robotic apparatus for traversing a selected
area autonomously that senses orientation relative to the Earth’s magnetic field or other
‘environmental signals’.” The robot can use a tool to cut, shovel, or dig; one of the uses being a
lawnmower function. A programmed computer that uses a digital compass to take orientation
readings during the operation of the device controls Dean’s programmable lawnmower. In
addition to the digital compass method, several alternative methods can be used for detecting the
location of the robot relative to some other “environmental signal” including detection of signals
from satellites such as GPS, detection of signals using cellular telephone communication towers
and technology, and detection of signals using radio or television broadcast antennas or towers or
broadcast satellites. Team 5 must carefully consider this patent because of the methods used to
implement Dean’s robot. However, the robot has many functions that Team 5 will not consider
using in their design. Team 5’s is only interested in designing a device that solely performs
functions as a lawnmower. During the design process, Team 5 must be aware of the concepts in
the patent to avoid potential patent infringements.
13
Yang, S.X.; Luo, C., 2004. A neural network approach to complete coverage path planning.
IEEE Transactions on Systems, Man, and Cybernetics, Part B: Cybernetics, Volume: 34 , Issue:
1, 718 – 724.
Martins, Goumlsta, Hallgren, Mats, Pettinaro, Giovanni C, Bergmark, Joumlrgen, 2001. Robot
system. United States patent application 20040093650.
McNeil, Dean, 2005. Guidance system for a robot. United States patent application
20060009876.
Wuertz, Robert M., Benson, Terrance G. 2004. Drive-by-wire lawnmower. United States patent
application 20050050871.
Madhavan, R., Durrant-Whyte, H.F., 2005. Terrain-aided localization of autonomous ground
vehicles. Automation in Construction, 13 (1), 83- 100.
Angott; Paul G., 2005. Unmanned utility vehicle. United States patent application 20060059880.
Hartwig, Stephan, Piikivi, Lauri, 2001. Pluggable server module for wireless remote controlling
of devices. United States patent application 20030055909.
TAURO, D., 1997. Test rig for studying lawnmower blade noise. Noise Control Engineering
Journal, 45 (2).
GERATE, W., 1972. Without noise and exhaust gases: electrical equipment for gardens.
Environmentally suitable lawnmowers for mains and battery operation suitable for small and
average size lawn areas. Elektromeister & Deutsches Elektrohandwerk, 47, 670.
ANDREWS, S., 2006. An experimental assessment of lawnmower blade loading. Journal of
Strain analysis for Engineering Design, 41, 151-160.
14
PALMER, R.J., 1995. Guiding principles in controlling small automated vehicles. IEEE
WESCANEX Communications, Power, and Computing, 2, 366-371.
POZO-RUZ, A., 2001. GPS and odometer data fusion for outdoor robots continuous
positioning. Proceedings of SPIE – The International Society for Optical Engineering, 4573,
195-206.
PATTON, W.G., 1952. Austempered lawnmower blades are hard, tough. Iron Age, 170, 8-90.
Martinez, J.L., Pozo-Ruz, A., Pedraza, S., Fernandez, R., 13-17 Oct 1998. Object following and
obstacle avoidance using a laser scanner in the outdoor mobile robot. Proceedings., 1998
IEEE/RSJ International Conference on Intelligent Robots and Systems, 1, 204-209.
15
Marketing Plan
1.0 Executive Summary
Our major objective for the Automatic Lawn Mower is to design an electric powered
lawnmower capable of being operated autonomously to reduce the need for direct human control.
Aspects ranging from ongoing growth of technology, to intensified work schedules to the limit of
physical mobility have pushed technology to become autonomous and provide less user
interaction. With these aspects The Automatic Lawn Mower will jump into a new upcoming
market.
1.2 Mission and Focus
Our device will focus on two types of lawn sizes ranging from medium scale yards to large scale
yards. The two main groups of individuals that we will focus on are those with limited leisure
availability and those individuals that are physically incapable of maintaining proper
maintenance of their yard. This device will be ideal for people with limited leisure availability in
the sense that the Automatic Lawn Mower will, after first and only initialization, free up the
home owner to pursue other interests, in contrast to be subjected to an afternoon of mowing the
yard. The individuals we are targeting under the physically incapable are those that are either
classified as elderly, sick, injured, or have limited mobility. Thus, this device will be ideal for
them by providing automatic lawn care with out strenuous and tiring labor. By, having the
device automatically maintain the yard, the physical and time consuming aspect of maintaining a
home owners lawn, will be reduced significantly, to amount of attention, allowing valuable
assistance and free time for the people purchasing the Automatic lawnmower.
1.3 Keys to Success
Our keys to success will be to provide a product that is cost effective, user friendly, and reliable.
The product will cost low enough to attract a large volume of home owners away from any
16
competition and steal consumers from the already existing manual products.. It will also be ideal
to provide sufficient features making the Automatic Lawnmower completely well rounded. The
Automatic lawnmower will need to have high durability, low maintenance as well as be
aesthetically pleasing. A major key to success will be to have low production cost, allowing for a
high profit margin.
2.0 Technology
The ability of an autonomous vehicle to determine its position and orientation with respect to a
frame of reference is defined as localization. In order to implement localization, a collection of
sensors are placed in various parts on the vehicle body for determining artificial landmarks,
direction of motion, and speed. The design also incorporates the use of global positioning
system, GPS, used in order to calibrate the steering encoders. A bearing-only sensor mounted on
the highest point of the lawnmower body can be used to detect strategically placed RF strips.
Thus, as the mower moves through the terrain, the information obtained from the other sensors
on speed and orientation along with the readings of the bearing-only sensor make it feasible to
realize a map of the terrain and follow the RF strips.
3.0 Market Analysis Strategy
Our market strategy will be to aggressively promote the idea of the autonomous lawn mower
through trade show demonstrations, commercials and brochures. Since the northern United
States are colder in climate we have decided to concentrate in the southern states. We will
concentrate our promotions to working class home owners and the physically immobile.
17
3.1 Market Segmentation
The Automatic Lawn mower segments it customers first by yard size, attractive only to those
homeowners with medium to large scale yards. We then segment our customers into those with
limited leisure availability and those that are physically incapable.
Yard sizes: The more strenuous labor of the large size yards will motivate customers to purchase
an automatic lawn mower. Larger yards require longer amounts of time attending to them
leading to larger amount of labor, especially when weather conditions are accounted for.
Limited Leisure: Those individuals with limited leisure availability due to the fact that their job
requires a lot of attention or that they must handle children, or have an active social life, will be
more interested in a lawnmower that will automatically cut the grass for them so that they may
concentrate on fulfilling the needs of one of the previous topics.
Physically incapable: Those individuals with limited mobility due to old age, injury, or illness,
will be interested in a lawnmower that requires little physical contact, assuring themselves
independence from needing help in maintaining their own lawns.
3.2 Target Market Segment Strategy
The strategy behind The Automatic Lawnmower target segmentation is to attract customers who
will benefit greatly from having an automatic lawnmower. It will not be difficult to attract
customers that have limited amount of leisure time and limited mobility. The unemployed, or
young and healthy people will provide a challenge. For this reason, The Automatic Lawnmower
will target people who will not be restricted to these aspects.
3.2.1 Market Needs
Business owners tend to be very busy people, but are often able to make their own hours.
Their job tends to keep them constantly active, focusing a lot of their time on
management and improving their business success. The medical field tends to be a 24
hours, with shifts falling anywhere in that range, people with night shifts or inconsistent
shifts tend not to have a steady schedule for yard maintenance. The elderly with limited
18
assistance and mobility will rely on an automatic lawnmower to take care of there needs
without imposing on others for assistance.
3.2.2 Market Growth
In years to come, the product will become dependable and reliable reassuring customers
that the product is indeed a required investment. The market will increase as more and
more consumers purchase the product and pass along the information on the reliability
and user friendliness. As consumers voice their suggestions, improvements can be made
into the design to accommodate more buyers.
4.3 Market Conclusion
The developments in the autonomous lawnmower market are in its early stages and are very
dependent on the increasing awareness among the homeowners. The market will witness steady
growth, until the dependability and usefulness has been proven. The market of new home
owners has improved tremendously allowing a wider market for success. Overall, the
autonomous lawn mower market is expected to succeed.
19
User Requirements Document
\
User Requirements
1. The system send/receive wireless signals.
2. The system will be self-propelled.
3. The system will have a safety shut-off.
4. The system will locate and avoid obstructions.
System Requirements
1. Wireless Interface
a. The wireless interface will receive signal to turn mower on/off.
b. The wireless interface will send signal to inform of safety concern.
2. Microcontroller
a. The microcontroller will be used to control wheel servos.
b. The microcontroller interface with wireless system.
c. The microcontroller will store the mowing path to memory.
d. The microcontroller will recall the mowing path from memory.
3. Servos
a. The servos will count wheel rotation.
b. The servos will turn the mower onto the proper path.
c. The servos will steer the mower out of the path of obstructions.
4. Sonar Sensors
a. The sonar sensors will detect the presence of obstructions.
b. The sonar sensors will direct the mower around the obstructions.
20
Interface Requirements
1. Receiver
a. The receiver will audibly alert user of safety issues.
b. The receiver will be hand-held.
c. The receiver will wirelessly connect to the mower.
2. Operation
a. The mower will be easily programmable.
b. The mower will be easily re-programmable.
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Proposal
1.0 Problem Statement
Due to increasing number of circumstances, which include timing constraints, and physical
incapability, the average homeowner is finding it increasingly difficult to maintain their lawn.
Our goal is to design a device that will mow the lawn using autonomous technology, while
keeping costs low.
2.0 Background Summary/Introduction
The developers of Autonomous Lawnmower will develop a lawnmower that will automatically
mow the lawn for the homeowner. This device will solve the localization problem, and use
wireless technology, to navigate through the terrain and thereby mowing the lawn. The necessary
steps in preparation for this proposal included literature research, patent research, the
determination of appropriate standards, market research, the assessment of design constraints, the
development of product requirements, assessment of design alternatives, and the development of
a functional block diagram. The team members have had extensive personal experience in
maintaining lawns and know the extent the physical aspects of the task. The realization of the
proposed project will require application of the team’s knowledge of microcontrollers, wireless
and sensor based devices.
3.0 Objectives
The major objective for the Automatic Lawn Mower is to design and build an electric powered
lawnmower capable of being operated autonomously to reduce the need for direct human control.
Aspects ranging from ongoing growth of technology to intensified work schedules to the limit of
physical mobility have pushed technology to become autonomous and provide less user
interaction.
22
The device will focus on lawn sizes ranging from medium-scale yards to large-scale yards. The
two main target markets for the device are people with busy schedules and people who are
physically incapable of using a normal lawnmower. By having the device automatically
maintain the yard, the physical and time-consuming aspects of maintaining a lawn will be
reduced significantly. In order to realize such a device, the team will concentrate on the
following major areas:

Operation:
o Wireless communications (remote control/device, device/location beacon)
o Control systems (wheel motors)

Intelligence: RAM (to remember user-input patterns)

Safety: object sensing (to avoid collisions with objects)
4.0 Plan
To achieve success in the design process, the team will attempt to accomplish the objectives in
phases (Table 1). Each phase consists of tasks relevant to accomplishing each objective of the
design process. The phases must be completed in order, while several tasks within a phase may
be completed simultaneously.
MAJOR OBJECTIVES
Phase
Operation
(1)
Intelligence
Safety
Rough draft design by hand
Hardware
Power Supply
Microcontroller
Sonar Sensors
Selection
Chassis & Drive
Development Board
Mowing Device**
Remote Controller
Location Beacon*
Transmitter/Receiver
LED’s, Buttons, LCD
Location Beacon*
(2)
Initial
Computer simulations
Construct prototype
Begin programming
Sensor placement
(Assembly & C++)
23
Construction vehicle
Real measurements
(3)
Interfacing
Components
Drive controller for motors
Continue programming
Remote Control settings
RAM development
Sensor settings
Vehicle transmitter
/receiver
Beacon transmitter
/receiver*
(4)
Vehicle starts
Pattern saves in
Test &
Vehicle moves
memory
Troubleshoot Vehicle turns
Sensors detect objects
Attach mowing
Vehicle stops
Vehicle uses pattern for
Remote control operates
autonomous operation
device**
Validate user requirements
* Location beacon is a separate device containing its own microprocessor & transmitter/receiver
** Mowing device does not have to be attached to implement major objectives
Table 1: Phases to achieve major objectives
4.1 Phase 1: Hardware Selection
Phase 1 is the most critical phase in the design process. It is important to select the right parts in
the beginning to ensure the design can be completed according to the schedule. Selecting the
wrong parts could lead to problems in subsequent phases that may not be able to be overcome.
Phase 1 requires finding the correct parts and ordering them once the team has consulted with the
team’s advisor. Since the objectives dictate what type of parts will be needed, the team can
select the parts most suitable to complete each task for each objective using by-hand analysis.
The team will consider using parts from reputable companies such as Mouser Electronics and
Motorola. The three major parts needed are the microcontrollers, motors, and
transmitter/receivers. The team will choose parts that can accomplish each task to meet user
24
requirements. In addition to choosing parts to accomplish each task, the parts must be
compatible with one another in order to implement phase 2 and, more importantly, phase 3.
4.2 Phase 2: Initial Construction
Once parts are selected in phase 1, the team can begin the initial construction phase. Using
computer simulations when necessary and the rough draft from phase 1, the team can construct a
prototype of the vehicle. The only task that must be performed before any other task in this
phase is the building of the chassis and drive. Since the microcontroller is the heart of the design
(Figure 1), the team can start programming the microcontroller after some of the tasks are
completed. For example, once the team builds the chassis and drive, the microcontroller can be
programmed to control the two wheel motors. During the building phase, the team make real
measurements to compare with the rough draft analysis. After all tasks in phase 2 have been
satisfactorily completed, the team can move to phase 3.
25
Figure 1: Functional Block Diagram
4.3 Phase 3: Interfacing Components
At this point in the design process, the team should have a good idea on whether or not the
design is meeting user requirements. Phase 3 is another critical phase where the interfacing of
components must be accomplished in order to move along further in the design process. If all
tasks are completed correctly in phase 1 and phase 2, the team should be able to complete the
tasks in phase 3 with average difficulty. All tasks from the previous phases contribute several
individual assemblies that will be combined together to form the overall design of the vehicle.
The individual assemblies are the following:

Drive transmission
o Motors
o Wheels

Wireless transmitter and receiver
26
o Vehicle
o Location beacon

Remote control device – communicates with vehicle only

Microcontroller
o Vehicle
o Location beacon

Sonar sensors
During the interfacing process, the team will focus on maximizing efficiency of components to
ensure the vehicle operates at an optimum level when tested in phase 4. This phase is needed to
make any necessary adjustments to the components’ settings. The team understands that some
complications may arise while interfacing components. To accommodate such complications,
the team will allot more time in the schedule to phase 3.
4.4 Phase 4: Test & Troubleshoot
Phase 2 and phase 3 incorporates some testing and troubleshooting. In phase 4 the team will
perform real-time testing of the completed prototype vehicle against user requirements. In
general, the vehicle should operate as follows:

Start when turned on by a manual switch or by remote control

Stop when turned off by a manual switch, remote control, or emergency shutoff

Move forward/backward and turn when controlled by remote control or by user-defined
pattern (must be able to at least traverse a slightly grassy surface)

Memory should hold a set number of user-defined patterns

Vehicle communicates with location beacon to stay on course (user-defined pattern)

Sensors detect objects so the vehicle can determine which objects are not passable
If any of these operations cannot be completed, the team must proceed to troubleshoot to correct
any malfunctions. Once malfunctions are detected and corrected, the team will retest the vehicle.
When the vehicle passes all required tests, the team can add on a mowing device that will cut as
the vehicle traverses the user-defined pattern.
27
5.0 Product

Product Specifications

Microcontroller source code

Wireless configuration

Controls schematics

Screenshots of working models

Physical models (prototypes)

Final Report
28
6.0 Schedule
29
7.0 Staffing
Our team is constructed of 4 members: April Fowler, Christopher Gerhardt, Jose Manzanares,
and Ranjith Raghunath. All the above mentioned students are currently enrolled in the College
of Engineering at the University of Texas at San Antonio (UTSA). April Fowler, a controls
engineering student, has extensive military experience working as an electronics technician. Jose
Manzanares, a controls engineering student, has background in networking and simulation
software. Both will be working on the design and implementation of the controls systems.
Christopher Gerhardt, a computer engineering student, also has extensive military experience in
software and hardware design. Ranjith Raghunath, a computers/communication engineering
student, has research experience in the design and implementation of digital signal and image
processing algorithms. They both will be working on the software and hardware interfacing.
8.0 Materials and Proposed Expenses
Item
Quantity
Estimated Cost per Item
Total Cost
Dragon12 Microcontroller
1
$139.00
$139.00
802.11b Wireless PC Card
1
$20.00
$20.00
Wireless Router
1
$35.00
$35.00
RC 1:8 Electric Car
1
$50.00
$50.00
Wireless Remote Controller
1
$14.00
$14.00
Power Supply
1
$15.00
$15.00
AM9128-10 , 2K*8 Static Ram
4
$5.00
$20.00
Sonar Sensors
8
$15.00
$120.00
Extraneous Costs
1
$100
$100.00
Total
$513.00
30
9.0 Budget
The proposed estimated costs are shown above. This is an estimate; however, $100 has been set
aside for the possibility of additional costs. There will be no travel or salary costs to account for.
To pay for the project, each member of the team has agreed to donate up to $300. If the project
costs grow beyond our total budget of $1200, outside entities will help to cover the difference.
When the project first began, the group began to solicit possible donations and as to this date,
have received promises for donations from 2 sources. These donations will be received upon
proof of expenditures exceeding $1200. The intent is to not exceed the given budget.
10.0 Concluding Paragraph
We would like to express our gratitude for the opportunity in being able to submit our proposal
for the design and implementation of an Autonomous Lawnmower. We hope that the ideas for
implementing this design has been conveyed and we await further approval. For any further
questions or comments please refer to Appendix
31
Design Alternative
The senior design project will be the realization of an autonomous lawnmower which will be
cost effective, user friendly, and portable. These features will be attained by the use of several
design techniques. The following three alternatives will be in consideration to aid with the
movement of the device:
1. Use of radio frequency (RF) markers and ground sensing techniques
2. Use of a camera for path guidance and pattern detection
3. Use of a remote control for the routing of different paths as desired by the user
The first alternative relies on the use of RF technology. RF strips are placed around the
lawn as markers. Sensors on the device will recognize the existence of these strips. As the
device moves around the terrain it will use the sensors to help solve the localization problem.
The device will also map the toured area based on the feedback that it receives from its sensors.
This type of design will force the user to purchase RF strips and place them in certain areas
within their lawn. This alternative may not be feasible due to the fact that the additional cost
may not be attractive to the consumer.
The second idea will use a camera to determine its path. This will aid in the recognition
of obstacles and the differentiation between grass and soil. This design would require adaptive
digital image processing techniques and an additional microcontroller. Due to the innate
difficulty of including another microcontroller, this may not be able to be realized in a timely
fashion.
The third concept allows a user to remotely control how their lawn is mowed by sending
and receiving wireless signals. The microcontroller will receive direction from a remote control
and then send a signal to the motors that drive the wheels. These motors will steer the wheels,
then send information to the microcontroller. This information, once received by the
microcontroller, will be stored into external random access memory (RAM). The next time the
user mows their lawn, the previous path will be recalled and the mower will operate
autonomously. This design can be realized in a timely and fiscally efficient fashion.
32
The weighing factors that affect the design deal with keeping the cost low, making it
autonomous, and portable. The first two design alternatives satisfy most the criteria levied by the
constraints; however the third design alternative seems be an advantageous option as the design
is less complex and has comparable features with respect to the other two.
33
Pugh Matrix
Use of radio frequency
Design Constraints
Weight
(RF) markers and ground
sensing techniques
The device will send and
receive wireless signals
The device will be self
propelled.
The device will have a
safety shut-off.
The device will locate and
avoid obstructions.
The device will use one or
more microcontrollers.
Use of a camera
Use of a remote
for path
control for the routing
guidance and
of different paths as
pattern detection
desired by the user
9
1
1
10
9
10
10
10
8
10
10
10
9
7
9
9
10
10
10
10
4
8
3
8
6
8
4
8
8
8
7
8
9
1
2
7
10
6
1
6
7
7
3
7
5
2
8
5
6
5
2
2
644
553
794
The device will have a
good graphical user
interface (GUI).
The device will use lowpower motors to propel
steer the wheels.
The device will be portable
and weigh less than 100
pounds.
The total cost of the device.
The scheduling constraint
of the members.
The complexity involved in
the design
Sustainability in the
market.
Compatibility with
engineering codes and
standards.
Total
34
Engineering Standards
IEEE Std 755: 1985. IEEE trial-use standard for extending high level language implementations
for microprocessors, IEEE Standards Board
ANSI B71.1: 2003. Outdoor Power Equipment - Walk-Behind Mowers and Ride-On Machines
with Mowers - Safety Specifications
ANSI B175.3: 2003. Outdoor Power Equipment - Grass Trimmers and Brushcutters - Safety
Requirements
EPA420-F-98-025. Small SI Engine Emission Standards.
EPA420-F-06-029. EPA Technical Study on the Safety of Emission Controls for Nonroad
Spark-Ignition Engines Below 50 Horsepower.
AS 1638-1991. Motor vehicles - Light alloy road wheels. American National Standards
Institute.
MIL-E-85082A. Encoders, Shaft Angle To Digital, General Specification. American National
Standards Institute.
QSTAG-397 ED.1. Design Standardization of Spark Plugs. American National Standards
Institute.
NCRP Report No. 86 (1986), Biological Effects and Exposure Criteria for Radiofrequency,
National Council on Radiation Protection and Measurements.
IEEE Std C95.1: 1991. IEEE standard for safety levels with respect to human exposure to radio
frequency electromagnetic fields, 3 kHz to 300 GHz.
35
I. ANSI B71.1: 2003. Outdoor Power Equipment - Walk-Behind Mowers and Ride-On
Machines with Mowers - Safety Specifications
The ANSI B71.1 safety specification applies to lawn mowers you would traditionally push.
This safety requirement helps ensure uniform operator requirements. This safety specification
must be taken into consideration in the design analysis of our project. The final product’s
design will be autonomous but throughout the experimental phases, constant monitoring will
be needed. There will be many instances where we will want to walk along with the device in
order to check calculations and monitor its progress in order to prove effectiveness. This will
ensure our design to have the best precautions available so that injury doesn’t occur to any of
our members. If our product is successful and pushed into the market place, our team will have
to design our vehicle to be as safe as possible, especially for our customer’s children. Lawn
mower-related injuries to children are common and can result in severe injury.
II. EPA420-F-98-025. Small SI Engine Emission Standards.
The EPA420-F-98-025 is a safety standard issued by the Environmental Protection Agency. It
functions as a means to control the amount of hydrocarbons (HC) and oxides of nitrogen
(NOx) that are emitted into the atmosphere from non handheld engines. The range of the
emission standard, limits to those engines with less than fifty horsepower. This will effect our
design when deciding the optimal engine to place on our chassis. The overall product must
meet those standards implemented by the Environmental Protection Agency in order for our
team to be able to be competitive in the lawn mower market. This standard will require a set of
controlled experiments in order to be certain that any alterations we make to the engine will not
affect the atmosphere and won’t be submitted to inspection by the EPA. This standard will
require proper planning to ensure its experiments won’t slow down our progress.
III. QSTAG-397 ED.1. Design Standardization of Spark Plugs. American National Standards
Institute.
36
The QSTAG-397 ED.1 is a design standard implemented specifically towards spark plugs. Its
function is to provide a standard design for spark plugs that are used in small engines. The
purpose to have such a design is to be able to have an interchangeable and mass produced
product. Implementing these standards into our design will let us and the potential consumer
to swap out any defective spark plug for an affordable price. Our team will take this into great
consideration when designing the engine for our autonomous lawn mower. Our wireless
ignition design idea requires us to do constant on/off simulations to test our product. Using a
spark plug that is standard and mass produced will allow us the ability to make quick changes
to the ignition part of the lawn mower, thus insuring proper progress in our experiments.
IV. IEEE Std C95.1: 1991. IEEE standard for safety levels with respect to human exposure to
radio frequency electromagnetic fields, 3 kHz to 300 GHz.
The C95.1 is a safety standard recommended by IEEE to prevent harmful effects in human
beings exposed to electromagnetic fields in the frequency range from 3 kHz to 300 GHz. The
range includes any experiments in either controlled or uncontrolled environments. The safety
standard states the maximum allowable time a person is capable under normal circumstance to
be in the vicinity of radio frequency electromagnetic fields with out causing any harmful
damage to the human. In our design, one of the ideas our group is contemplating, is using
radio frequency identification tags to control the movement of our autonomous lawn mower.
This will require us to place these identification tags around the lawn in specific locations in
order to properly control the autonomous lawn mower. In doing so we will have to monitor
and measure the strength of the electromagnetic fields the identification tags will produce to
keep it under the maximum allowed. This safety standard will require proper planning and
multiple experiments, we will need to plan early and be effective in order to ensure progress in
implementing our design on time.
37
High-Level Block Diagram
Description:
Each team will develop a functional block diagram that fits on one page in landscape orientation.
Each specific function will be represented by its own functional block (Power Supply, microcontroller, ADC, motor controller, serial-optical converter, etc.). Lines with arrows designating
the direction of information exchange will be drawn to show all interfaces between various
functional blocks. If the communication is in both directions, one line with two arrows or two
lines with one arrow each can be used. Each block should be clearly labeled. The type of
interface (the lines) should also be labeled with the mode of the interface (analog, digital, optical,
etc.). Additional information may also be added to suit you needs.
38
39
Appendix – A
Contact Information
April Fowler
(210) 232-8259
fowleropolis@yahoo.com
Christopher Gerhardt
(210) 601-9480
cgerhardt@ieee.org
Jose Manzanares
(210) 392-2640
joe_manzanares@yahoo.com
Ranjith Raghunath
(210) 663-9399
Ranjith_nath@ieee.org
40
Appendix – B
MAJOR OBJECTIVES
Phase
(1)
Operation
Intelligence
Safety
Power Supply
Microcontroller
Sonar Sensors
Hardware
Chassis & Drive
Development Board
Mowing Device**
Selection
Remote Controller
Location Beacon*
Transmitter/Receiver
LED’s, Buttons, LCD
Location Beacon*
(2)
Initial
Rough draft design by hand
Begin programming
Sensor placement
Drive controller for motors
Microcontroller
Sensor settings
Remote Control settings
RAM development
Computer simulations
Construction Construct prototype vehicle
Real measurements
(3)
Interfacing
Components
Vehicle transmitter/receiver
Beacon
transmitter/receiver*
(4)
Vehicle starts
Test &
Vehicle moves
Troubleshoot Vehicle turns
Vehicle stops
Pattern saves in memory
Sensors detect objects
Vehicle uses pattern for
Attach mowing
autonomous operation
device**
Remote control operates
Validate user requirements
* Location beacon is a separate device containing its own microprocessor & transmitter/receiver
** Mowing device does not have to be attached to implement major objectives
Table 1: Phases to achieve major objectives
41
Appendix – C
Ghantt Chart
42