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1. JAMES C. CONWELL
Department of Mechanical Engineering
Louisiana StateUniversity
GEORGE D. CATALANO
Department of Mechanical Engineering
Louisiana StateUniversity
JOHN E. BEARD
Department of Mechanical Engineering
Michigan Technological University
ABSTRACT
The seniordesign sequence at Louisiana State University is a
two semester, design, build and test experience. Groups of
two, three orfourstudents work togetherin a team setting to
produce a functioning prototype which meets predetermined
design goals. One particularproject, which had as its goal the
requirement to extend the reach of an occupant confined to a
standard sized wheelchair, was used as a mechanism to inte-
grate the development of critical and creative thinking skills
necessary to solve technical problems into the undergraduate
mechanical engineering curriculum. Special attention was paid
to the nature of creativity and exercises were introduced in
orderto facilitate this historically neglected aspect of engineer-
ing education. The result of this effort was a unique wheel-
chair, which provides the occupant access to shelves located
overtheirhead orobjects on the floorvia an adjustable height
seat.
I. INTRODUCTION
As engineering educators, how do we provide the engineers
of tomorrow with the problem solving skills needed in a rapid-
ly changing technological world? At Louisiana State
University, we have used the mechanism of the senior design
course sequence to meet this challenge. The two semester
sequence forces students to move beyond the lower levels of
learning (memorization and recitation) as described in Bloom’s
taxonomy(4)
to the highest levels or most difficult (design,
implementation and evaluation). In To Engineer is Human(1)
,
Petroski writes “the idea of design—of making something that
has not existed before—is central to engineering.”
Harrisberger(2)
notes in a chapter entitled “
The Design Process . .
. Doing Engineering Problem Solving”
:
‘‘The crux of the design process is creating a satisfactory
solution to a need . . . it is what engineering is all about—
using knowledge and know-how to achieve a desired out-
come. Designing is problem solving. It is creative problem
solving.’’
These goals can be accomplished through the careful guid-
ance of a senior design team as it moves through the various
stages of a design project. One such project, the subject of this
report, challenged the student team to design a device to
extend the reach and improve the accessibility of physically
handicapped individuals confined to a wheelchair.
II. PROBLEM STATEMENT AND THE DESIGN
PROCESS
Imagine someone working feverishly away on a sketch of a
new gadget, a new electronic circuit diagram, or a water
drainage elevation plan with pencil and sketch pad in hand. In
a moment of contemplation, the pencil slips and falls to the
floor, out of immediate reach.
Imagine someone brewing a cup of coffee and noticing the
sugar bowl perched precariously on the top shelf in the kitchen
pantry, just beyond the reach of his or her outstretched hand.
Trivial challenges to be sure—to pick up the pencil off the
floor or to reach up for the sugar bowl, unless that same person
is confined to a wheelchair.
These challenges were the basis of a task given to a group of
senior level mechanical engineering students: to design and
build a device that allowed the wheelchair occupant to pick up
objects off the floor and to grasp something from a raised shelf.
Once the task was identified, the students were provided
three different models for analyzing the processes that serve as
the foundation for effective solution of problems. The models
chosen are those described by Koberg and Bagnall(5)
, Bransford
and Stein(6)
and Harrisberger(3)
. In fact, a great deal of research
focused on the steps used in successful problem solving has
taken place over the last two decades; so the choice of a partic-
ular model is somewhat arbitrary. The Koberg and Bagnall,
Bransford and Stein, and H arrisberger approaches all were
accessible to our students, and thus, proved to be useful frame-
works for activities and discussions throughout the design
sequence.
Along with the introductions of the different models,
emphasis was placed on the importance of being able to criti-
cize ideas (critical thinking skills) and generate alternatives
(creative thinking skills). Critical thinking is convergent, seeks
to assess worth or validity of something that already exists, and
applies accepted principles. It involves the analysis of factual
claims, the logic of arguments, and the analysis of basic
assumptions. Creative thinking is divergent, usually seeks to
generate something new, and often violates accepted princi-
© 1993 American Society for Engineering Education. Reprinted from Journal of Engineering Education, Vol. 82, No. 4, October 1993. Journal of Engineering Education 227
A Case Study in Creative Problem Solving in
Engineering Design

2. 228 Journal of Engineering Education © 1993 American Society for Engineering Education. Reprinted from Journal of Engineering Education, Vol. 82, No. 4, October 1993.
ples. Creative thinking is driven by a desire to seek the original;
it values mobility, revels in exploration, requires flexibility and
respects diversity. In problem solving, there is a shifting back
and forth between the critical thinking skills and the creative
thinking skills. In fact, research has shown that critical and cre-
ative thinking skills are synergistic, the development of one set
of skills will aid in the development of the other set.
Critical thinking skills are perhaps somewhat easier to teach
as they are easier to quantify(9)
. Factual accuracy can be ascer-
tained, fallacies in the development of a logical argument can
be identified and the validity/applicability of basic assumptions
can be checked. The nature of creativity and the development
of creative thinking skills is a much more abstract and daunting
task for the educator(10,11)
. Some strategies exist for enhancing
creative solutions to problems, for example, Bransford and
Stein(12)
list the following methods:
1. Make implicit assumptions explicit through searching for
inconsistencies, worst case scenarios, making predictions and
seeking criticism.
2. Fractionation involves breaking ideas into component
parts, thereby breaking down ‘programmed’assumptions.
3. The use of analogies.
4. Brainstorming incorporates the first three activities into a
group setting in order to facilitate the quantity of new ideas.
5. Incubation requires breaks in a determined search for a
solution and helps to alleviate mental fatigue.
6. Communication of new ideas to others, for it is in the
process of putting ideas into words that new ideas come to
mind.
III. APPROACH TO THE DESIGN PROBLEM
After the introduction to design methodology and the
importance/development of both critical and creative thinking
skills, a student design team was given the following problem:
Design ‘something’tohelp an individual (perhapsa para-
plegic) confined to a wheelchair pick up an object off the floor
and retrievean object resting on thetop shelf of a kitchen cab-
inet.
That was the extent of the formal direction given to the
three students.
In order to have the students become personally involved
with the project, they were led through a series of role-playing
exercises, designed to help them more fully understand the
limitations of a wheelchair occupant. This caused the design
team to become personally involved with the project, an
important factor in determining the success of problem solving
efforts.
Next, the students were asked to respond to a series of ques-
tions such as “What is the scope of the project?”, “What is
fixed?”, “What can I control?”, “What are my resources?”, and
“Where can I seek additional/outside advice?”. Here the design
group quantified the task by measurement of distances from
the floor to the tips of an extended arm of an average height
person sitting in a wheelchair and the height such an average
person could reach over his/her head. Critical thinking skills
were essential in that this stage of the problem solving involves
the gathering of relevant information and the dissection of
main tasks into small sub-tasks.
In the case of a partially paralyzed individual, the main
problem became one of extending his/her accessibility in a ver-
tical plane. A standard wheelchair already provides lateral tra-
versing capability so that it is this additional degree of freedom
of movement that is the central issue, and hence one of the
major design obstacles. To meet and overcome this barrier, the
students were challenged to use their creative thinking skills
both individually and collectively in brainstorming to generate
possible solutions to the posed problem. To assist in the gener-
ation of ideas, the students were introduced to the notions of
leap-frogging (using ideas/methods/solutions from other
descriptions) and piggybacking (modifying/amplifying ideas
previously given).
A partial listing of the ideas generated included:
● A periscoping gripper
● An air cushion (Hovercraft-type) wheelchair
● Movable shelving
● Movable flooring
● An adjustable height wheelchair
Having generated a number of possible approaches, a final
decision was made after a careful consideration of its ‘doability’
within the limitations of the course and whether or not it suc-
cessfully achieved the identified goals. To aid in this selection,
the design team was introduced to attribute listing -an evalua-
tive technique of identifying pros and cons of possible options.
Lists generated for the periscoping gripper and the adjustable
height wheelchair are shown in Table 2.
The design team then further refined each of these choices,
using critical thinking skills combined with engineering analy-
sis of each of the above design choices. The engineering studies
included the following:
Table1. Comparison of Problem Solving Models.

3. Force and Stress Calculations
Stress levels and factors of safety were determined for all
critical members contained in each of the design choices.
Ease of Manufacturability
A determination of the number of machining operations, as
well as tolerance requirements, assembly difficulties and avail-
ability of materials and parts were considered.
Reliability and Safety
Component fatigue, overall stability, inherent user dangers
and miscellaneous safety considerations for the individuals who
might be adjacent or in proximity to the finished project were
all considered.
The list of attributes (contained in Table 2) was then com-
bined with the information collected from engineering calcula-
tions to determine a potentially ‘best’ design solution.
Following an extensive investigation, the design team chose
the adjustable height wheelchair concept. This particular
choice was made for several basic reasons:
● Capability of the finished project to meet a wide variety of
the needs of a disabled individual. In addition to the basic
needs of a person confined to a wheelchair (transportation
and ease of use) an adjustable height wheelchair would pro-
vide vertical access in a unique and compact package.
● The amount of training required for an individual to use this
design would be minimal. Many occupants of wheelchairs
are already familiar with the operation of electric wheel-
chairs, and a adjustable height wheelchair would be practical
extension to that concept.
● An adjustable height wheelchair would be a unique design,
and enable the student group to design, build and test a
device that is not readily available upon the open market.
This would require extensive applications of innovation and
creativity.
● Many current users of wheelchairs indicated to the students
that an adjustable height wheelchair seat would be the most
readily accepted design choice.
Implementation means “making real” or “realizing that
which has been intended”. H aving chosen the adjustable
height wheelchair as their solution, the students set out to
make the chair a reality.
The following is an outline of the parameters and con-
straints for the wheelchair as discussed and agreed upon by the
design team.
The main task for the wheelchair is to provide disabled
individuals with greater reach by lowering and raising the seat.
The variable elevation was chosen to extend from 10 inches to
40 inches from the floor. These elevations were determined in
the following manner:
1. The lowest position was determined by having each
member of the design team sit on a stack of blocks. The height
of the stack was adjusted until an object on the ground could
easily be picked up without excessive or abnormal bending at
the waist. When the height of the stack was approximately 10
inches, each member in the group could pick up the object.
This distance was also verified using the dimensions of the
standard 50th percentile male and female.
2. The elevation of the seat for the normal seated position
was determined through measurement of existing standard
wheelchairs. In addition, the dimensions of wheelchairs were
obtained from several wheelchair manufacturers’ catalogs.
Nearly all sources indicate that approximately 18 inches above
the ground is a standard seat elevation.
3. The highest elevation was determined by measuring the
distance that can be reached by a standing person and subtract-
ing the distance that can be reached in a seated position.
Approximately a 35 inch seat elevation was required for an
average-height seated person to obtain comparable reach with
a standing person.
Possible solutions to this overall design problem were
obtained through individual ‘brainstorming’. Each design team
member was required to conceive and sketch twenty different
mechanisms or ideas that could accomplish the lift require-
© 1993 American Society for Engineering Education. Reprinted from Journal of Engineering Education, Vol. 82, No. 4, October 1993. Journal of Engineering Education 229
Table2. ComparativeAnalysisof BasicDesign Choices.

4. ments. At this stage, no restrictions were placed on the design,
even far-fetched ideas were encouraged.
Each of the ideas was presented to the whole team for dis-
cussion and evaluation. All of the designs were given consider-
ation. Designs which did not seem physically or economically
possible were eliminated. For example, it was decided early on
that any modification to a wheelchair should not change the
basic size (or ‘footprint’) of the chair. Many of the suggestions
made at this stage were, of necessity, discarded due to this con-
straint. For example, a Hovercraft type wheelchair would have
required a large skirt which extended outside the frame of the
wheelchair to support the weight of the chair and the occu-
pant. Of the remaining designs, the best five were selected on
the basis of:
● Component availability: A determination was made regard-
ing whether components could be located at local supply
houses or required the order of a specially constructed ele-
ment.
● Economics: As with all of the groups in the senior design
sequence, this particular group was required to complete the
project within a certain budget. Which of the designs could
be constructed and remain within the budget?
● Manufacturing Ease: The number of machining operations,
material choices and assembly procedures were all consid-
ered.
● Appearance and General Operation: The student group did
not want to attract any undue attention to the user of this
type of specialized wheelchair. As a result, appearance
became a major design criteria. Additionally, ‘user friendli-
ness’ was considered at each stage of the design process. To
help determine evaluative criteria for this step, the student
group utilized input from a local disabled individuals sup-
port group. This group suggested several criteria by which
to judge the design, including the required location of con-
trols, overall placement of the lift mechanism, and final
appearance of the device.
After several design team meetings and discussions (high-
lighted in Table 3), it was determined that the best lift mecha-
nism for the wheelchair would be a double scissors mechanism.
Two other major subsystems of the wheelchair were identi-
fied by the project group as the base subsystem and the leg
support subsystem.
As previously stated, a fundamental design criteria for the
wheelchair base was that its overall dimensions should not be
230 Journal of Engineering Education © 1993 American Society for Engineering Education. Reprinted from Journal of Engineering Education, Vol. 82, No. 4, October 1993.
Table3. ComparativeAnalysisof FiveLift Mechanisms.

5. larger than the dimensions of a standard wheelchair base. The
design team also determined that the attachments of the lift
mechanism should be integrated into the design of the base.
This is in contrast to a modular type of design where the lift
and the base would be very distinct entities. The modular
base/lift design was given significant consideration. If a modu-
lar lift mechanism were designed so that it could be easily
adapted to fit standard wheelchairs, the mechanism could be
manufactured and marketed alone. H owever, after further
analysis, it was determined that the modular design concept
could not satisfy the constraints set for this project. The inte-
grated base/lift design was deemed superior to the modular
design for the following reasons:
● The integrated design would provide a more stable, secure
and safe base for the wheelchair.
● The integrated design would have greater continuity in
appearance.
● The integrated design would cost less to manufacture than a
modular type of unit.
The design team decided that the integrated base design
would be best for this project.
The leg support subsystem had to meet one important
design parameter. Namely, the leg support system must rotate
and extend as the seat lowers from the normal seated position
to the lowest elevation.
After a variety of ideas were considered, the team selected
the two best ideas—a combination telescoping and a sliding
mechanism. Further evaluation by team members was per-
formed to determine the feasibility of implementing the two
concepts into a workable design. This investigation revealed
that a slider mechanism under the seat was a more practical
solution. The extension of the leg support could be accom-
plished by simply attaching a push device at the end of the
slider. The rotation could be accomplished by attaching anoth-
er member to the push bar and the support bar.
Discussions with individuals familiar with the needs of the
disabled (relatives, doctors, nurses and the disabled them-
selves), assisted in the identification of the other design para-
meters and constraints associated with the leg support subsys-
tem. First, the leg supports should be completely and easily
removable from the wheelchair. This is desirable because it sig-
nificantly reduces the size of the wheelchair during storage and
transportation. Secondly, the leg supports should lock securely
at the desired position to provide an adequate sense of security
and stability for the user. Finally, the leg supports should rotate
to the sides, completely out of the way of the front of the
wheelchair. This rotation allows for easier entry and exit to and
from the wheelchair.
The development of the leg support subsystem followed a
similar progression as in the design of the lift mechanism.
Each member of the design team “brainstormed” to conceive
and sketch several ideas for obtaining the required rotation and
extension. Each idea was then presented to the project group
and critically evaluated, using many of the criteria previously
discussed (cost, manufacturability, etc.) as well as the input of
the disabled individuals serving as consultants to this project.
The evaluation of the adjustable height wheelchair has been
an ongoing process. At the completion of the fabrication of the
chair, a series of tests were run in order to document the actual
achieved performance. Information included the following:
● Approximate operational times between electrical battery
charging.
● Confidence and comfort of the occupant when the chair is in
the fully extended upward position.
● Ease of manufacturability and any/all problems associated
with the adjustable height wheelchair’s size and weight.
● Responsiveness of the control system and any noted associat-
ed discomfort to the occupant, notably at the beginning and
ending of the vertical movement. .
● Effect of the environment on the integrity of the electronic
system (especially with regards to rain, snow, etc.)
Many of these parameters had to be evaluated by the dis-
abled individuals from the local support group. As a result,
some of the criteria were rather nebulous (‘the control joystick
seems to be in the right position’) but illustrated to the design
group the types of feedback typically received for a project of
this type. The design team’s successful efforts were duly noted
in their selection as the outstanding senior design (out of a
class of eighteen projects) project in the Department of
Mechanical Engineering in May, 1990. The award was decid-
ed through the vote of the faculty and student body and is the
highest recognition of achievement given in Mechanical
Engineering at Louisiana State University. The project serves
today as a standard by which the efforts put forth by subse-
quent design teams are judged.
REFERENCES
1. Petroski, H., To Engineer is Human, Vintage: New York, 1992,
p. vii.
2. Harrisberger, L., Engineermanship, Brooks/Cole: Belmont, CA,
1982, p. 39.
3. Bransford, J. D. and Stein, B., T he Ideal Problem Solver,
Freeman: New York, 1983, p. 3.
4. Gross, R., Peak Learning, Tarcher: Los Angeles, CA, 1991, pp.
142-145.
5. Koberg D., and Bagnall, J., The All New Universal Traveler,
Kaufman: Los Angels, CA, 1981.
6. Bransford, J. D. and Stein, B., T he Ideal Problem Solver,
Freeman: New York, 1983, pp. 11-32.
7. Harrisberger, L., Engineermanship, Brooks/Cole: Belmont, CA,
1982, pp. 39-48.
8. Lombardi, L., Moral Analysis, SUNY Press: Albany, 1988, pp.
1-42.
9. Grudin, R., The Grace of Great Things, Tichsnor and Fields:
New York, 1990, p. 5.
10. Diaz, A., Freeing the Creative Spirit, H arper Collins: San
Francisco, 1992, p.
11. Bransford, J. D. and Stein, B., The Ideal Problem Solver,
Freeman: New York, 1983, pp. 93-108
12. Dyson, F., Infinite in All Directions, Harper-Row: New York,
1989, pp. 36-41.
© 1993 American Society for Engineering Education. Reprinted from Journal of Engineering Education, Vol. 82, No. 4, October 1993. Journal of Engineering Education 231