Tri-Bin Trash Trolley
APD2006-04
5 December, 2006
The T-Bins:
Sue Dean
Aki Motoyama
Kevin Ng
Marie Wolbert
ABSTRACT:
As the Baby Boomer generation continues to age, the need to design products for this user group
becomes increasingly important. Among the various household chores, trash disposal is
universal. However, as people age, this chore becomes more difficult to perform, with some
elderly overwhelmed by the process to the point of resorting to storing trash in basements or
unused rooms. A design that properly addresses the needs of the elderly is often a design that
will be useful for the general population. Therefore, this design team endeavored to create an
ergonomically sound and aesthetically pleasing trash bin with recycling capabilities that would
provide user support for the trash removal process.
In order to meet these ideals, the Tri-Bin Trash Trolley was designed with three bins as well as
providing the capability of supporting a person in the same way a walker is often used. The
dimensions were determined using ergonomic, engineering, economic and aesthetic optimization
routines. This produced a device that was made with correct height for usage by 80% of the
elderly population, with strength enough to support a 250 pound person, with minimal bin
weight, while being packaged in a way that would be pleasing to the eye.
1
TABLE OF CONTENTS
1. NOMENCLATURE: ................................................................................................................ 4
2. INTRODUCTION .................................................................................................................... 5
Definition of Need ...................................................................................................................... 5
Design Problem........................................................................................................................... 5
Design Requirements .................................................................................................................. 6
3. PRODUCT DESCRIPTION..................................................................................................... 6
Selected Concept......................................................................................................................... 6
Previous Designs......................................................................................................................... 7
Competing Products.................................................................................................................... 7
Concept Selection Process .......................................................................................................... 9
4. ENGINEERING ANALYSIS................................................................................................. 10
Height of Trolley....................................................................................................................... 10
Design Optimization: Weight vs. Strength of Trolley .............................................................. 10
Negative Null Form of Optimization........................................................................................ 10
Storage space of bin:................................................................................................................. 13
Smell from trash:....................................................................................................................... 13
5. ENVIRONMENTAL IMPACT.............................................................................................. 13
6. EMOTIONAL/AESTHETIC ANALYSIS ............................................................................. 14
The Effect of Color in Design................................................................................................... 14
Kansei Engineering................................................................................................................... 15
7. ECONOMIC ANALYSIS ...................................................................................................... 17
Profit function ........................................................................................................................... 18
Constraints ................................................................................................................................ 18
Optimal Configuration .............................................................................................................. 19
8. MARKETING ANALYSIS.................................................................................................... 19
Determining the market size ..................................................................................................... 19
Comparing the market size with supply.................................................................................... 20
Analyzing the survey results..................................................................................................... 21
9. PRODUCT DEVELOPMENT PROCESS ............................................................................. 24
10. PRODUCT BROADER IMPACT.......................................................................................... 25
11. CONCLUSION....................................................................................................................... 25
12. REFERENCES ....................................................................................................................... 25
APPENDIX A: User Identification & Identification of Stakeholder Needs................................. 26
APPENDIX B: Observations & Interviews with Elderly (Intended Customer)........................... 28
APPENDIX C: Trash Bin Benchmarks: ....................................................................................... 30
APPENDIX D: Quality Function Development Chart (QFD) ..................................................... 38
APPENDIX E: Reverse Engineering description of Foot Pedal Type Trash Bin ........................ 39
APPENDIX F: Initial Survey: ...................................................................................................... 44
APPENDIX G: CAD Drawings.................................................................................................... 46
APPENDIX I: Gantt Chart............................................................................................................ 52
APPENDIX J: Engineering Analysis............................................................................................ 53
APPENDIX K: Environmental Impact Analysis.......................................................................... 57
APPENDIX L: Kansei Analysis ................................................................................................... 58
APPENDIX M: Economic Analysis............................................................................................. 60
2
APPENDIX N: CBC Survey-Sample ........................................................................................... 62
APPENDIX O: Four Level CBC Survey Betas as Extracted From Sawtooth Program............... 64
APPENDIX P: CBC System Multinomial Logit Estimation....................................................... 66
3
1. NOMENCLATURE:
Symbol
Description
Engineering Analysis
Wtrolley
Weight of Trolley
I
Moment of Inertia
r
Radius of beams
Mmax
Max Moment
P
Loads on beams
L
Length of beam
A
Distance between the end closest to the user and the beginning of the handle
σmax
Max stress on beam
c
Distance from neutral axis to the extreme fibers
F
Maximum or critical force on a vertical column
K
Critical force constant
E
Modulus of elasticity
l
Unsupported length of the column
Vbin
Volume of bin
Hhuman
Human height
H
Hypotenuse length
FCol
Force on columns
Economic Analysis
HT
Height of trolley
LT
Length of trolley (front face)
DF
Diameter of frame cross section
ρT
Density of frame material
EF
Young’s modulus of frame material
HC
Height of cabinet
LC
Length of cabinet (front face)
VTrsh
Volume for trash
STrlly
Strength of trolley
WTrlly
Weight of trolley
Q
Demand
$
Price
Π
Profits
Market Analysis
qm
Total final demand
$mkt
Price
STrlly
Strength of trolley
WTrlly
Weight of trolley
VTrsh
Volume for trash
Kansei Engineering
Y1
Color of cabinet sides , where wood= -1, white= +1
Y2
Type of cabinet edges, where sharp= -1, rounded= +1
Y3
Color of counter top, where maroon= -1, white= +1
X1
Design of Trolley handles, where straight= -1, round= +1
X2
Material of Trolley handles, where rubber= -1, plastic= +1
X3
Color of Trolley frame, where brown= -1, metallic= +1
4
2. INTRODUCTION
As Americans age, they are living in smaller accommodations where they take care of basic
chores with limited capabilities or in assisted living accommodations where there are varying
amounts of support provided. Often, dealing with trash removal becomes a problem for those
living alone with regular reports of trash being accumulated in basements or unused rooms due
to a lack of easy disposal. For those elders in assisted living, effort is made to keep them as
independent as possible for as long as possible to keep them active. The design team decided to
develop a trash bin system that would meet waste disposal needs in one central location, with
aids for waste removal in an aesthetically pleasing manner. The main objective has been to
provide a stand alone set of bins (in order to handle both trash and recyclable materials) that
would provide support to make it easier for the intended users to remove trash either to the
outside trash bin or to the street.
Definition of Need
Improvements in health care, nutrition and the environmental have increased life expectancy in
many parts of the world, particularly in the United States. According to the Federal Interagency
Forum on Aging Related Statistics, almost 13% of the American population is age 65 or older.
In Michigan, the percentage of elderly people is about 10 to 12.9%. In 2011, the baby boom
generation will start turning 65 [1].
About 31% of non-institutionalized elderly people live by themselves. For women who are age
75 or older, 50% of them are living alone [2]. Even in situations where elderly become
weakened, household chores, including trash disposal, must still be completed. There are many
activities during trash disposal, such as separating garbage according to type, managing the
recyclable materials, and transferring the garbage to the outside trash bin which are difficult for
the elderly to handle by themselves. What might be an annoyance for the younger generation
might be a painful and dangerous experience for the elderly.
There are many types of trash bins in the market, but few are designed to have multiple bins that
allow for an all-in-one trash/recycling solution and even fewer are designed for the elderly.
Some trash bins can be troublesome to use, or even dangerous for populations with limited
mobility. Therefore, it was decided that designing a trash and recycling storage bin especially
for the elderly would be a welcome addition to the current market.
Design Problem
Although there are freestanding multi-bin solutions available in other countries, the only multibin solutions available in the US are incorporated into built in cabinets that require significant
installation costs. Additionally, the design team was not able to find trash bins that solved the
problem of easing trash removal to outside trash bins. Therefore, the design team decided to
develop a design that would provide a freestanding multi-bin trash bin that provided a means to
minimize the difficulty of removing trash to outside trash containers. Additional work was done
on providing a bag retaining system to insure that trash bags would not fall out of place, leaving
users with a mess.
5
Design Requirements
Based on the information received from customer observation (APPENDIX B) and the QFD
chart (APPENDIX D), it was determined that the bin should provide a means of supporting
removal of trash to an outside bin, provide enough bin volume to be able to hold a few days
worth of trash while fitting into an out-of-the-way area in a small Pullman type kitchen. In order
to provide a product that would be manageable by most elderly people during trash removal, the
team decided to provide a trolley that would have wheels while minimizing the weight. It was
also determined that the trolley should be able to support the weight of a 250 pound person.
Parameters for the product were determined to be:
ƒ
Cabinet
o Height – based on common kitchen counter top height, as well as suggestions
from AARP for kitchen design
o Footprint – based on fitting into the width of a common kitchen cabinet, while
providing for the market differentiating corner design
ƒ
Trolley
o Height – based on ergonomic guidelines
o Footprint – designed to fit inside the cabinet
o Bin Volume – limited by footprint size, this was also designed to have the main
trash compartment most closely aligned with common trash bag sizes
o Trolley strength – it was decided that the trolley would need to support a 250
pound person using the trolley as a walker
From these parameters, the design team used engineering analysis to optimize the variables of
the weight of the trolley (to be minimal) and the diameter of the trolley frame (minimal) while
meeting the objective of meeting the strength requirements. These optimizations were
performed separately on wood, aluminum and steel, with the final selection being to manufacture
the frame out of aluminum tubing.
3. PRODUCT DESCRIPTION
Selected Concept
The design team arrived at a final design concept as shown in Figure 1 on the next page. This
design provides a cabinet that houses a trolley with an aluminum frame that holds three bins; a
large bin for general trash storage and two smaller bins for recyclables. The frame has grips to
be used during the movement of the trolley, so that the customer can use the trolley as a walker
during trash removal. An added design innovation inside the cabinet is the placement of an out
of the way shelf that holds trash bags for the user. This allows for easy access to trash bags
when replacing the trolley to the cabinet after taking the old trash out.
The assembly and detail drawings are included in APPENDIX G
6
Figure 1: Final design concept of the Tri-Bin Trash Trolley
Previous Designs
Current trash bin designs generally provide flip-type lids, some drawer designs and trash
containers that are incorporated into built in cabinet arrangements, both for trash storage alone or
with multi-bin designs that provide storage for recycling. Initially, the major focus for the team
was to look at lidded systems, with bag retainers that had additional containers for recyclable
trash when performing a study of the current state of the art for trash bins. Multi-bin systems,
which were found mainly in foreign markets, varied between systems that provided a framework
for open containers, drawer type systems that had containers slide out from a cabinet, tilt out
systems that were also contained inside a cabinet, and those trash bins that had lids that were
opened manually, mechanically (usually with a foot pedal) or electronically.
Competing Products
APPENDIX C shows the benchmark designs that the team found individually, both by searching
on the web and visiting local retail establishments. This benchmarking study not only provided
insight into current state of the art, but also provided a means for each individual team member
to develop ideas for their ideal trash bin design. The multi-bin containers from Japan show
designs that are both space saving and convenient to use. Some of the American made bins
provide ideas for designs that may be more aesthetically pleasing for the American market.
Although not all bins are shown, it was noted that stainless steel bins seem to be the current style
favored for the high end consumer, while molded plastic containers fit into the low to mid-price
range. Some cabinet type units were found with a variety of wood finishes available (these were
mid- to high-priced units).
A reverse engineering analysis was conducted on one of the popular concepts currently in the
market to learn about the design features and considerations (APPENDIX E: Reverse
Engineering description of Foot Pedal Type Trash Bin
Review of State of the Art
Upon completion of the patent search and competition analysis, the team determined that, by
bringing in some of the space saving concepts from the Asian market while allowing for the
functionality and styling of the American products, a new style of trash bin could be designed
7
that would provide a trash/recycling station for the kitchen that would be ideally suited for
seniors that are living in independent housing, especially where space may be limited.
Patent Search
Of the many patents pertaining to trash bins, most of the recent patents focus on lid opening
mechanisms or bag retention devices. Additional patents relate to tilt out or drawer mechanisms.
The design team initially looked at lid mechanisms (a sample is shown in Figure 2), with the
thought of having a typical single bin unit that would have an easy to open lid. There was also
some research done to look at tilt out set ups that would accommodate a multi-bin system. One
patent provided some insight into a framed system with casters, which ended up being a
rectangular, one bin version of the final product (see Figure 3).
Figure 2: Patent figure from automatic lid device for a trash bin (US Patent # US 6,774,586 B1)
Figure 3: Frame based trash bin with casters (US Patent # 5,048,712)
8
Concept Selection Process
Based on the list of design criteria, each concept was assigned a relative weight of importance;
with each one compared to the other designs to determine which design best met the design
requirements.
Design #2
Design #3
Design #4
Design #5
10
0
D
+
0
+
7
-
A
0
+
+
6
+
M
0
0
+
8
-
D
-
0
-
10
++
A
+
++
++
8
-
T
+
0
-
8
-
U
-
-
-
6
0
D
-
+
+
4
10
+
++
A
M
0
0
0
0
0
0
10
++
D
0
0
0
+
0
-
70
0
27
26
45
16
0
33
52
16
31
0
17
8
25
Total Points
39
0
10
18
20
Design
Criteria
Eliminate
smells
Maximize
storage space
Aesthetically
appealing
Convenient to
refill trash bags
Convenient to
open bin
Safe for
children and
animals
Reasonable
price
Maximize entry
size for trash
Leak proof
Convenient to
transport trash
outside house
Convenient to
transfer trash
into road side
collector
Weight
Sketches
Design #1
Figure 4: Pugh Chart
9
4. ENGINEERING ANALYSIS
To satisfy the design objectives of the trash bin, various analysis techniques were completed.
The dimensions for the trolley and cabinet were established through the research of waist heights
for the elderly and countertop heights. Decisions concerning the materials to use were made
using beam loading analyses and optimization of the weight versus strength trade off. Other
design considerations such as placing a wooden or acrylic face on the front of the trolley were
modeled using CAD software.
Height of Trolley
The height of the trolley was determined using Equation 1. According to Kawaguchi’s
Biomechanical Calculation Formula for Optimum Kitchen Counter Heights, this calculation
results in the most appropriate counter height with the least amount of stress for the user.
(Hhuman)/2+5-10 cm
(Eq. 1)
where, Hhuman is the user height. Since the average height of both men and women over the age
of 65 in the US is 1.424 m, the height of the trolley was calculated to be .712 m (30 inches). In
addition, this counter height was noted by the AARP as an on optimum height for surfaces in
elderly homes. This will allow minimal bending and low stress for the user when changing trash
bags or taking out the recycling.
Design Optimization: Weight vs. Strength of Trolley
The goal of this design is to minimize the weight of the trolley, yet still have it support a 250 lb.
person leaning on grips connected to the top horizontal beams. Material selection was completed
after performing failure analyses and weight calculations to determine the “optimal” design.
The main variables in the design were the material and cross sectional areas of the trolley
structure beams. The parameters were that the trolley needed to be able to hold approximately
125 lbs of force on the side of the trolley with a safety factor of at least three. This simulates the
worst case scenario of a 250 lb. person leaning his or her body completely on the two sides of the
trolley and can be seen in Figure 5. Since the dimensions of the structure were calculated to have
the least stress on the user and hold certain volumes, the beam lengths and the height of the
trolley were considered constraints in the design optimization. The objectives were to minimize
the weight of the trolley, Wtrolley,(and therefore force to pull it up and down stairs) while
maximizing its strength. This engineering model can be seen in negative null form below.
Negative Null Form of Optimization
minimize Wtrolley (Length of Beams, Cross Sectional Areas of Beams, Density of Material)
subject to:
Height of Vertical Columns, l = 0.712 m
Hypotenuse Lengths, H = 0.720 m
Side Lengths, L = 0.495 m
σmax (applied forces & locations ) ≤ σyield / 3
Force on Columns, Fc ≤ Critical Force, F
10
125 lbs.
125 lbs.
Figure 5: Simple Beam Failure Analysis
Simulating a simply supported beam, the loading on the top side beams were simulated as having
two equivalent loads located at variable points. This can be seen in Figure 5, where L is the
length of the beam, A is the distance between the end closest to the user and the grips on each
side, and P is the load on the beam.
L
A
P
y
x
Figure 6: Simply Supported: Two Equivalent Loads at Variable Points
For the failure analysis, the following equations were used:
5π r 4
I=
4
(Eq. 2)
where, I is the moment of inertia for a circle and r is the radius.
A⎞
⎛
M max = − PA⎜1 + ⎟
L⎠
⎝
(Eq. 3)
where, Mmax is the maximum moment, located at the grip.
c
A⎞⎛ 1 ⎞
⎛
(Eq. 4)
= − PA⎜1 + ⎟ ⎜
⎟
I
L ⎠ ⎝ 5πr 3 ⎠
⎝
where, σmax is the maximum stress as a result of the worst case scenario loading and c is the
distance from neutral axis to the extreme fibers, or the radius in this case.
σ max = M max
11
Another type of failure that could result within the trolley during use is the buckling of the
vertical columns shown in
Figure 7.
Figure 7: Buckling Failure Example
To complete this analysis, moments were taken from one fixed end of the simply supported beam
to determine the vertical force on the other end. The summation of forces in the y-direction was
used to calculate the final unknown force. These vertical forces were compared to the maximum
allowable force for the vertical columns.
F=
( Kπ 2 EI )
l2
(Eq. 5)
where, F is the maximum or critical force on a vertical column, K is a constant whose value
depends upon the conditions of end support of the column (4 for both ends fixed), E is the
modulus of elasticity, and l is the unsupported length of the column.
Substituting the equations into the design optimization gives the following mathematical model:
minimize: WTrolley = ρπr 2 (3l + 4 L + 2 H )
subject to:
r 3 ≥ k1 → r ≥ k1'
12
k1 =
(
3PA 1 + A
(5π 4 )σ
)
P →k = 3
1'
yield
(
3PA 1 + A
(5π 4 )σ
P
)
yield
r 4 ≥ k 2 → r ≥ k 2'
k2 =
Fc l 2
Kπ 2 E 5π
( 4)
→ k 2' = 4
Fc l 2
Kπ 2 E 5π
( 4)
or
r ≥ max(k1' , k 2 ' )
The results of the optimization prove that the aluminum is a better choice of material in
comparison to oak. To satisfy the same objectives, the 2-inch diameter dowels of oak would be
needed rather than the .5-inch diameters for aluminum, as seen in APPENDIX J. Using
aluminum would allow for the volume of the trash and recycling being much greater even though
it is a little heavier. In an attempt to reduce the weight of the trolley, aluminum tubing 1/8-inch
thick with an outer diameter of 1” was analyzed for failure, but was not able to support the worst
case scenario loads.
Storage space of bin:
The storage space of the bin was important and needed to accommodate a full standard tall
kitchen trash bag (Eq. 6). The volume is dependant on the shape and size of the bin.
Vbin (shape, size) ≥ Vacceptable (standard tall kitchen trash bag)
(Eq.6)
The triangular shape of the trolley separates further into a square section for the trash and two
triangular sections for triangular recycling buckets. A volume of 3,577 in3 for the garbage
section ensures more than enough storage space for the 13 gallon (3,003 in3) standard tall kitchen
trash bag.
Smell from trash:
To eliminate the smells permeating from the trash and recycling area, it is necessary to have the
trolley completely enclosed when not in use. However, this has proposed another challenge to
consider. Originally, the team chose to wrap the trolley in canvas. In this case, an addition to
the front of the cabinet would be needed since the top of the trolley does not completely touch
the cabinet. Another idea is to place a wooden or acrylic plate on the front of the trolley. This
would not only enclose the trolley when in the cabinet, but would also increase aesthetics of the
product.
5. ENVIRONMENTAL IMPACT
During the design process, the team considered their material choices with an eye towards
making this product as green as possible while still keeping the costs down during the early
design and development stages. Although the beta plus design has some environmental
considerations, there are further design changes that could be implemented that would reduce
ecological impact.
13
An analysis of the Tri-Bin Trash Trolley is included in APPENDIX K, to date, the team has
endeavored to make the trash bin greener with the following design decisions:
ƒ
ƒ
ƒ
ƒ
ƒ
Choosing to use responsibly harvested wood products for the cabinet
The trash bin and cabinet will be sold as a customer assembled kit to reduce the amount
of storage and stowage required to get the product to market
The aluminum frame allows for use of a commonly available recycled material
Ceramic tile for the cabinet’s top has a low ecological impact during the product lifecycle
The alternative counter surface shall be made of bamboo, which is a highly renewable
resource
6. EMOTIONAL/AESTHETIC ANALYSIS
The Effect of Color in Design
In order to design a trash bin that will attract customers visually, the team applied the principles
of proportionality as well as using the emotional effects of colors.
The principles of proportionality were applied mainly to the cabinet, since the trash bin itself is
kept inside the cabinet most of the time. The dimension of the cabinet has to satisfy both the
golden ratio of proportionality while still maintaining the ergonomically driven height of 35
inches, which is a standard height of American kitchen cabinets. However, when the golden
ratio was directly applied to the cabinet height, the width of the cabinet would be approximately
21.6 inches, which is too narrow for the trash bin to fit inside. To solve this problem, the team
designed a colored rectangle meeting the golden ratio dimensions to fit in the middle of the
cabinet, with a neutral color used to fill the extra space. This would maintain the idea of
proportionality while still keeping the original dimension of the cabinet.
According to the Color Guidebook written by Chika Sato, the appropriate colors for a kitchen are
those colors with warm tones, so that cooked food will look better. The book also suggests using
less color to provide emphasis to the color of the food itself. Additionally, since the cabinet is
intended to hold objects on its top or to provide a place for elders to lean on while throwing the
trash, color plays a vital role for giving the impression that the cabinet is stable. From the same
book, the author describes how darker colors give a feeling that the object is heavy and hard.
This effect could give stable feeling to the cabinet. By combining the idea of using dark color
and having warm tones in the kitchen, Bordeaux, or a maroon color (both are dark tone red,
almost brown) would be appropriate for the cabinet. These colors will be used for the trash
trolley, in order to suggest stability to users as they use the trolley as a walker with elders leaning
on it.
Oppositely, for the rectangle with golden ratio, a lighter color is more appropriate since lighter
color would make the front face of the cabinet to look lighter, and give the feeling that they are
easy to handle. As the team finalized colors they kept in mind that it is best to use fewer colors
because unity is important for kitchen decor.
Red
Pink
Orange
Yellow
strength, energy, activeness, vivacity
cuteness, gentleness, femininity, peacefulness, gives mental complacence
gentleness, thoughtfulness, brightness, released feeling, increased independence
increase mind, sense, confidence, also intensify self-centered thoughts
14
Blue
Green
Purple
White
Black
Gray
Sky Blue
Brown
excels in relaxation and settling, appeals sincerity and wisdom
harmony, honesty, happiness, direct calm and peaceful image
gives images of preciousness, mystery, elegance, peacefulness and calmness
cleanliness, purity, sanctity, makes your feeling neutral
coercion, dignity, strength, despair, sin, death, sorrow
sincerity, calmness, mediocrity, modesty
freshness
sincerity
Figure 8: The Meanings of Various Colors
15
Kansei Engineering
Kansei (meaning psychological feeling in Japanese) engineering analyzes one’s perceptions
when using products and incorporates them into the design. The objective of the Kansei analysis
was to determine the most important or desired customer emotions when using the trash bin.
This allowed the modification of certain design characteristics to promote these responses. For
this activity, the product was separated two areas - the cabinet and the trolley.
The most important feelings to convey to the users and the design attributes that can be altered to
create those feelings are shown below. The perceptions each have an assigned importance
ranking between 0 and 10 (10 being the highest importance).
Cabinet
Perceptions and assigned
importance
Design Characteristics
Variables and assigned
characteristic values
Color of cabinet sides Y1
Type of edges Y2
Color of counter top Y3
Wood -1 Vs White +1
Sharp -1 Vs Rounded +1
Maroon -1 Vs White +1
Perceptions and assigned
importance
Design Characteristics
Variables and assigned
characteristic values
Stable
Strength
Convenient to use
Cleanliness
Design of handles X1
Material of handles X2
Color of frame X3
Straight -1 Vs Round +1
Rubber -1 Vs Plastic +1
Brown -1 Vs Metallic +1
Cleanliness
Convenient to use
Durability
Aesthetics
9
6
6
6
Trolley
6
6
9
6
A survey was conducted to gather user perceptions of our product for the full range of possible
design combinations based on our design characteristics. The survey and its raw results averaged
can be found in APPENDIX L.
Using the survey results, a regression line for each design characteristic was derived for each
perception.
Cabinet
Cleanliness:
Convenient to use:
0.3125 Y1
-0.15625 Y1
Durability:
-0.25 Y1
Aesthetics:
-0.28125 Y1
+ 0.375 Y2 +
0.4375 Y3
+ 0.84375 Y2 - 0.03125 Y3
+ 0.3125 Y2 +
-0.375 Y3
+ 0.65625 Y2 - 0.15625 Y3
+ 0.625
+ 0.21875
+ 0.25
+ 0.28125
16
Trolley
Stability:
-0.625X1
– 0.0625 X2 + 0.1875 X3
+ 0.6875
Strength:
-0.21875 X1 – 0.09375 X2 + 0.21875 X3 + 1.28125
Convenient to use:
-0.09375 X1
-0.15625 X2
+0.28125 X3 +0.65625
Cleanliness:
-0.38125 X1 +0.30625 X2
+0.63125 X3 +0.18125
The table below summarizes the relationships between the design variables and the user
perceptions. The design variables are chosen to maximize the perceptions based on the equations
above.
Perceptions
Design Variables chosen to maximize user satisfaction
Cabinet
Cleanliness
Convenient to use
Durability
Aesthetics
Color cabinet side
White
Wood
Wood
Wood
Type of edge
Rounded
Rounded
Rounded
Rounded
Color counter top
White
Maroon
Maroon
Maroon
Trolley
Stability
Strength
Convenient to use
Cleanliness
Design of handle
Straight
Straight
Straight
Straight
Material of handle
Rubber
Rubber
Rubber
Plastic
Color of frame
Metallic
Metallic
Metallic
Metallic
Conclusion
The result of the Kansei analysis demonstrates that there are perception trade offs for the cabinet
(cleanliness, durability, convenience and aesthetics) as well as for the trolley (stability, strength,
convenience and cleanliness). The coefficients of the different variables were evaluated and
assigned importance values. This combines the four perceptions for both cabinet and trolley into
one equation that represents the overall experience (shown below).
Overall perception of Cabinet: -0.0486 Y1 + 0.528 Y2 + 0.0208 Y3 + 0.375
Overall perception of Trolley:
-0.303 X1
-0.0188 X2 + 0.324 X3 + 0.697
Based on these equations, the following combination of design variables were chosen to
maximize the user satisfaction.
Cabinet
Color cabinet side
Wood
Type of edge
Rounded
Color counter top
White
Trolley
Design of handle
Straight
Material of handle
Rubber
Color of frame
Metallic
17
7. ECONOMIC ANALYSIS
The economic analysis was used to determine the optimal set of design variables and price by
relating the design variables and price to the profits. A mathematical equation was then derived
to show profits as a function of design variables and price. The profits were then maximized by
varying the design variables and price under relevant engineering and practical constraints until
an optimal configuration was found that minimized cost while still meeting the engineering
requirements.
This analysis focused on these three design attributes:
•
•
•
Volume [V] – Trash capacity
Strength [S] – Maximum vertical downward force the trolley can withstand
Weight [W] – Weight of trolley
These design attributes in turn depended on the design variables which are defined below:
Trolley:
HT = Height
LT = Length
D = Diameter of cross-section of frame
ρT = Density of frame material
E = Young’s modulus of frame material
Cabinet:
HC = Height
LC = Length
LC
HC
HT
LT
Figure 9: Illustration of variables
The design attribute will be functions of the design variables:
Volume = V{ HT, LT }
18
Strength = S{ HT , E, D }
Weight = W{ HT, LT, D, ρT }
Profit function
Defining profits Π = Price x Quantity – Quantity x {variable cost + fixed cost}
Where,
Quantity = Q {P, V, S, W}
Variable cost = V {Cost material trolley, cabinet surface & cabinet counter top, HT, LT E, D, ρT, HC, LC}
Fixed cost = $40
The profit equation given in terms of design variables would be:
⎡
⎤
⎢ ($
⎥
)
/
⋅
2
⋅
+
+
2
2
⋅
+
m
L
H
L
T
T
T
⎢ trlly . mat ' l
⎥
2
⎢
⎥
⎛
⎞
L
Π = P ⋅ [400 − 2 . 5 ⋅ P + 140 ⋅ V + 5 ⋅ S − 75 ⋅ W ] − Q ⋅ ⎢ ($ cab .ext . mat ' l . / m 2 ) ⋅ ⎜⎜ 2 ⋅ L C H C + C
⎟⎥
⎟
2 ⎠⎥
⎢
⎝
⎢
⎥
2
⎞
⎢ $ cntr .top . mat ' l / m 2 ⋅ ⎛⎜ L C
⎥
40
+
⎟
⎜
⎢⎣
⎥⎦
2 ⎟⎠
⎝
(
(
)
)
Where,
2
V = H T ⋅ LT ⋅ 2
3
4
S = 3 ⋅ π ⋅ E 2⋅ D
4⋅ H
W=
g ⋅ ρ T ⋅π ⋅ DT
2
2
(L
T
+
)
2 ⋅ L T + 1 .5 ⋅ H T + 2 .5
The derivation of our profit function is shown in APPENDIX M.
Constraints
•
•
•
•
•
•
•
•
•
•
•
•
•
•
V ≥ 0.4m3
S ≥ 100N
W ≤ 50N
$0 < P < $160
HT = 0.680m
LT = 0.720m
HC < 1.5m
LC < 0.8m
LT < LC
HT < HC
E > 0 GPa
0m < D < 0.10m
ρT > 0 kg/m3
Q>0
19
Optimal Configuration
Using Excel’s solver, the best configuration based on the (selected material choices) is:
• Cabinet height (C) = 0.9m []
• Front cabinet length = 0.72m []
• Diameter of cross-section of frame = 0.015m[]
• E =6.9 GPa
• Density of frame material (ρT) = 0.0027 kg/m3
• P = $160
• $ Material trolley = $7/m
• $ Material cabinet casing = $3/m2
• $ Material counter top = $3/m2
• V = 0.47 m3
• S = 158000N
• W= 2.5 N
• Material choice for trolley = aluminum
The Excel output for this analysis is provided in APPENDIX M.
8. MARKETING ANALYSIS
The objective of the marketing analysis was to estimate the size of the potential market, then use
a conjoint survey to determine user preferences with regards to the design characteristics and
price. The results obtained from the surveys provided information about the nature of the utility
derived by consumers from each design characteristic and price as they vary. The profits were
then maximized by varying the design characteristics and price to capture the largest possible
market share by maximizing the user’s derived utility.
Determining the market size
Two possible market groups for the product were identified.
The first category includes individuals that satisfy all the following three criteria:
• 65 years of age and older
• Have an annual income of $20000 or greater
• Lives alone, or with other elderly people
The second category includes individuals that reside in assisted living facilities.
The first category
The population of elders of age 65 and older = 35.5 million
Of this population, the number of elders having an annual income of at least $70,000 or greater is
1.3 million.
The probability that a member of the product target group purchasing the product is related to his
or her living arrangement. The Tri-Bin Trash Trolley was designed to aid the elderly in
managing their trash disposal. Hence those who live alone would be more likely to purchase the
product, compared to those who live with spouses or other family members. The table below
illustrates the living arrangements of the elderly.
20
Detail of elders (+65) with income of $70,000 or more
Married (spouse present)
Married (spouse absent)
Widowed
Single
771800 (about 385900 couples)
34600
335000
45400
Therefore a total of 415000 elders full into the first category of potential users of our product.
We assume that married elders with spouses present tend to be younger, and possibly divide their
household chores; they are less likely to buy the trash bin. We estimate that 0.5% of those elders
living with spouse would purchase our product.
385900 * .005 = 1930 units → approximately 1900 units
Elders living alone would have a greater need for our product. We estimate that 1.5% of the
elders would purchase our product. This category would include those married with spouses
absent, widowed and single.
415000 * .015 = 6225 units → approximately 6200 units
Therefore, the total number of units we predict the first category of user will purchase
= 6200 + 1900 = 8100 units
The second category
The number of elderly living in assisted housing = 500000
Working along the assumption that on average, 2 elders would share one room, it is estimated
that there will be approximately 250,000 rooms.
It was then estimated that 5% of the assisted living rooms would purchase the trash bin.
Therefore the amount of units that would be purchased:
250000 * .05 = 12500 units
Summing up the market size
The two categories of users were then added together to determine the total market size:
12500 units + 8100 units = 20600 units
Comparing the market size with supply
It was calculated that the total number of trash bins that would be manufactured a year based on
the following:
The potential number of trash bin units than can be manufactured in a day – 100 units
The number of business days = 5 days * 50 weeks = 250 days
The total number of trash bin units in a year = 100 kits * 250 days = 25000 kits
Therefore the forecast of demand in relation to supply is considered to be feasible.
Relating product characteristics to utility and conjoint survey
The utility of our product was determined to be a function of a number of design characteristics.
21
Utility = Utility {Price, Weight of trolley, Strength of Trolley, Volume for trash}
Each design characteristic was separated into different levels. These levels were later used in a
conjoint survey that was conducted. The survey was designed to understand how utility is
derived by users, and the relationships and trade-offs between the various characteristics. A
sample of the survey and its raw results can be viewed in APPENDICES N and O.
Design Characteristics
Levels
Price
$60-$79
$80-$99
$100-119
Weight of Trolley
Approximation for
survey
40 N
≈1 gallon
milk
80 N
≈2 gallons of
milk
120 N
≈3 gallons of
milk
Strength of Trolley
Approximation for
survey
50 N
Only trash
20 N
60 N
Can be leaned Weight of a
on lightly
small person
100 N
Weight of a
large person
Volume for Trash
Approximation for
survey
0.2m3
Plastic
grocery bag
0.5 m3
Paper grocery
bag
2 m3
Tall kitchen
trash bag
1 m3
Office trash
bin bag
$119-$140
Analyzing the survey results
The survey provided the Part-worth (Beta) for each attribute level of each characteristic. A
positive part worth (Beta) would indicate positive utility for the user, while a negative part worth
would indicate a negative utility. The magnitude of the part worth would indicate the amount of
positive or negative utility involved. The Betas are shown in the table below.
Attribute Information from Conjoint Survey
Price
Level
$60-$79
$80-$99
Beta
0.73677
0.31944
Weight of Trolley
Level
1 gal of milk
2 gal of milk
Beta
0.12054
0.00387
Strength of Trolley
Level
Only trash
Beta
-0.36628
Volume of Regular Trash
Level
Plastic bag
Beta
-0.29098
$100-119
-0.42274
3 gal of milk
-0.12441
Can be leaned Weight of
on lightly
Small person
-0.00042
0.28453
Paper bag
-0.08751
$119-140
-0.63348
Office trash bag
-0.17183
Weight of large
person
-0.08217
Tall kitchen bag
0.55032
Using the values of Beta determined from the Sawtooth program, the maximum likelihood
formula to compute the Betas and spline interpolations for the continuous functions with respect
to price and design characteristics. The layout and different configurations of design
22
characteristics used in determining the best fit curves based on the initial Betas are shown in
APPENDIX P.
New values of Beta were later derived from maximizing the Chi-square fit of our curves. The
new Beta values are shown below.
Best fit-Beta values
Price
Level
Best-fit Beta
Weight of Trolley
Level
Best-fit Beta
Strength of Trolley
Level
$60-$79
0.73677
$80-$99
-2.04738
$100-119
-3.28726
1 gal of milk
0.12054
2 gal of milk
1.204791
3 gal of milk
0.094018
Only trash
Can be leaned
on lightly
-1.06653
Wt of small
person
0.181432
Weight of
large person
-0.68429
Paper grocery
bag
1.182203
Office trash
bin bag
2.414367
Tall kitchen
trash bag
2.752997
Best-fit Beta
-0.36628
Volume of Regular Trash
Level
Plastic
grocery bag
Best-fit Beta
-0.29098
$119-140
-1.3555
The utility curves for the different attributes are shown on the next page.
Price versus. Part worth
Strength of trolley vs. Part worth
1.00
0.40
0.50
0.20
0.00
0.00
$0
$20
$40
$60
$80
$100
$120
$140
Part worth
-0.50
-1.00
-1.50
-0.20
0
20
40
60
80
100
120
-0.40
-0.60
-2.00
-0.80
-2.50
-1.00
-3.00
-1.20
kg
-3.50
Weight Trolley (kg) vs Part worth
Voum e of trash (M^3) vs. Part
w orth
1.40
1.20
3
part worth
1.00
2.5
2
0.80
1.5
0.60
1
0.40
0.5
0.20
0
0.00
-0.5 0
0
2
4
6
8
10
12
14
0.5
1
1.5
2
2.5
M ^3
weight(kg)
The demand curve was found to be:
23
Total _ Utility
qm = {e
Utility _ of _ no _ choice
eTotal _ Utility +e
} * market _ size
Where the
•
•
•
Total utility = sum of all the individual utilities based on their ‘level’.
Utility of no choice = 1.03
Market size was determined to be 20600.
The optimal values of the design characteristics to optimize the user utility are:
Optimal value
Price
$70.0
Weight of trolley
80 N
Strength of trolley 700N
Volume for trash
0.85m3
Total Utility of new product
Total demand
Utility
0.74
1.20
0.26
2.18
4.38
70% of market
= 0.70*20600
≈14000
Linearizing the demand function and comparing it with the economic analysis results
The linearized form of the demand curve we derived above is:
q m = {−0.035 * Pr ice − 0.0008 * Strength + 0.0001 * Weight − 1.875 * Volume + 3} * market _ size
Where Price is in $, Strength in Ns, Weight in Ns, and Volume in m3.
Based on this new linearized demand function, the optimal design variable was set and compared
to the design variable values derived from the economic analysis. The table below illustrates this
comparison.
Design Variable Marketing analysis
Economic analysis
Price
Strength
Weight
Volume
$160
158000N
25N
0.47 m3
$70
1000N
80 N
1 m3
24
Since the marketing analysis was conducted using a conjoint survey, it could be assumed to more
accurately describe market demands. If decisions were based on the market analysis, the price
would need to be reduced and volume has to be increased compared to the economic analysis to
increase demand. However, the market survey was completed by a different demographic than
the targeted customer for this product. Therefore, it was decided to continue with the design
from the engineering/economic analysis stage of product development until a new market survey
can be completed with a focus group of elderly users. The marketing analysis does provide
insight into a possible redesign of a trolley with a greater weight and a significantly lesser
strength that would be better accepted into a younger less wealthy market demographic.
Comparing elasticities with previous analysis
Assuming an initial market of 1000 to be consistent it with the previous market analysis.
q m = −3.5 * $ TUnit + 0.08 * S Trlly − 0.01 * WTrlly + 187.5 * VMBin + 300
The table below compares the elasticities of the various design characteristics derived from the
market analysis, and the previous economic analysis.
Elasticity
Marketing analysis
Economic analysis
Price
Strength
Weight
Volume
-3.5
0.08
-0.01
187.5
-2.5
5
-75
140
The elasticities for price and volume correspond reasonably well for both analyses. However the
elasticities of strength and weight appear to be much greater based on the economic analysis.
Since the marketing analysis was conducted based on a conjoint survey of user preferences, it is
possible that the importance of strength and weight in the economic analysis were overestimated.
Factoring in the relative numerical nature of the design variable inputs, it could be concluded that
price and volume are the most elastic design characteristics.
9. PRODUCT DEVELOPMENT PROCESS
As shown in APPENDIX H, the design team followed a process of using the input from the
elderly customer focus group to develop a set of design objectives. Then a QFD was used to
analyze the level of importance to apply to the design objectives. Benchmarking provided a
background to work from for developing the initial design concepts. A Pugh matrix was then
used to down select to a couple promising designs. From that point, the design was further
refined based on input from the engineering, economic and marketing analyses.
The main change in perspective that was generated was the amount of change that can take place
in a product during the development process. In the case of this design team, the product was
changed from a rectangular product to a triangular corner cabinet after the alpha prototype stage.
By taking the additional time for the mathematical optimization on this project, there was no
significant cost associated with this change, other than having to revisit several design
calculations.
10. PRODUCT BROADER IMPACT
The design of trash bins can have more of an affect on the user than just supplying a convenient
means of disposing trash. Just as a trash bin known as the littershark in Zurich, Switzerland, has
been designed to ward off graffiti, birds and bombs, hold in spills and ease trash collection [8],
the Tri-Bin Trash Trolley has more than trash storage in mind. By providing a means to give
user support for the trash removal process the design team hoped to design a product that will
enable elderly users to have a feeling of independence as well as give the user a reason to, at a
minimum, get up and out every day or two to remove their trash to an outside bin or collection
location. Especially in the assisted living environment, elderly have to deal with a loss of
independence that can be very difficult to accept. This product allows for the user to hold on to a
minimally demanding chore that can aid in a sense of self sufficiency.
11. CONCLUSION
Designed with the elderly needs in mind, Tri-Bin Trash Trolley combines both waste and
recycling capabilities into a single, aesthetically pleasing, and compact unit. Housed within this
unit is a trolley, which not only holds two recycling bins for the separation of paper and plastics
and a larger trash bin which also functions as a walker type support for the user. The trolley is
strong enough to be able to support a 250 pound person leaning on the frame while transporting
the contents outside. As the baby boomer generation continues to grow and the average life
expectancy increases, the need for products designed for the elderly will continue to increase.
Though the Tri-Bin Trash Trolley is designed specifically for these weaker users, this innovative
product has the potential to be successful amongst those who have space limitations or are
simply environmentally conscious as well.
12. REFERENCES
1. (http://www.agingstats.gov/chartbook2000/population.html)
2. (http://www.aoa.gov/prof/Statistics/profile/2005/2.asp)
3. “American Red Oak Wood.” Matweb – Material Property Data.
http://www.matweb.com/search/SpecificMaterial.asp?bassnum=PTSAV. 30 Oct. 2006.
4. Kawaguchi, Aki,Takashi Yukawa, and Matsuki Yamamoto. “Biomechanical Calculation
Formula for Optimum Kitchen Counter Heights.” No.82 Special Issue on Technologies for
Supporting the Aged. http://ww w.mew.co.jp/e-tecrepo/82e/main02.html
5. “Simply Supported: Center Load.” http://efunda.com/formulae/solid_mechanics/beams/
casestudy_display.cfm?case=simple_centerload#target. 30 Oct. 2006.
6. “Young’s modulus – wikipedia, the free encyclopedia.”
http://en.wikipedia.org/wiki/Young's_modulus. 30 Oct. 2006.
7. Shih, T., “Trash Bin Equipped with an Automatic Lifting Lid” US Patent # US 6,774,586 B1
8. Wolters, R., “Treadle Top Refuse Container”, US Patent # 5,048,712
9. Giussani, B., “Littershark Prowls European Cities”, BusinessWeek.com, Visited 11/15/06.
www.businessweek.com/innovate/content/oct2006/id20061009_518484.html
26
APPENDIX A: User Identification & Identification of Stakeholder Needs
Development of User Profile:
-
What is the user’s lifestyle and background?
•
•
-
What are the user’s expectations?
•
•
-
The user will usually think about getting rid of the trash at hand, then if the trash
needs to be removed to the outside trash bin
Is it possible to use the product in a way that was not intended?
•
-
It will be used throughout the day
What is the user thinking about while using the product?
•
-
It will be used anytime the user generates trash
How often will the product be used?
•
-
It will be used to store trash until it is time remove to outside rubbish removal bin
When will the product be used?
•
-
To be able to get rid of trash easily
To not be expected to exert large forces, or move their bodies into positions that are
anything but the most stable of positions
How will the product be used?
•
-
Elderly and handicapped people that spend most of their time indoors
Less active than younger people, with limited balance and strength
It could be used to store other things besides trash
What are the user’s limitations (cognitive, physical, etc)
•
The user’s physical abilities in terms of strength, balance and flexibility
Stakeholder Identification
-
Who will use the product?
•
•
-
Who will buy the product?
•
•
-
The elderly
People purchasing for the elderly (assisted living suppliers, children and caregivers)
Who will sell the product?
•
-
The elderly, people of limited physical capabilities
General public
Specialized retail stores (kitchen suppliers, hardware stores)
Who will manufacture the product?
•
•
Trash bin manufacturers
Companies specializing in products for the elderly
27
-
Who will transport the product?
•
-
Who will store the product?
•
•
•
-
The elderly, people of limited physical capabilities
Caregivers
Who will recycle or dispose of the product?
•
-
Trash bin manufacturers
Companies specializing in products for the elderly
Retail establishments
Who will maintain the product?
•
•
-
The above listed manufacturers
Caregivers
Whom else the product will affect?
•
•
•
Members of the household where elderly person lives
Caregivers
Pets and animals who go near the trash bin
Outline of activities surrounding the use the trash bin:
Generation of trash
Pull Open Trolley and Dispense Trash
Close Trolley
Trash Bins Get Filled
Return Trolley to Cabinet
Transport Trolley and Trash to
Outside Trash Disposal
Remove Trolley from Cabinet
28
APPENDIX B: Observations & Interviews with Elderly (Intended Customer)
Observation 1
Francile Clevenger is 78 years old and lives alone in a small house in Ann Arbor. She has an
older trash bin for her trash and uses the city-provided recycling bins for her paper and
recyclable container trash (see Figure 10). Since the recycling containers are bulky and
unsightly, she keeps them in another room, which forces her to carry recyclables extra steps.
The trash containers do not add any aesthetic value to her home.
Figure 10: Trash bin and recycling containers for Francile Clevenger, Age
78 (metal cans in foreground contain pet food).
If given the choice Francile says that she would like to have a single container to house all trash,
with more manageable recycling containers. Her volume requirements usually consist of a single
tall kitchen garbage bag, ~5” of newspapers/cardboard with container recyclables fitting into a
typical paper grocery bag (often less).
Bending over to pick up things below 12-15” off the ground is difficult for Francile and she likes
the height of her current trash bin for lifting the trash out on trash day. However, she has three
pet peeves with her current trash bin. The first being that food tends to catch on the lid if she’s
not careful, the second being that the bag comes off the rim and gets ‘lost’ in the trash and lastly
that the lid tends to flip out of the pocket and fall out of place (see Figure 11).
Figure 11: Out of place lid due to bag interfering with
hinge pocket.
Observation 2
29
Gender: male
Age: 86 years old
He is a very lean man and has walking problems, because his muscles are getting weaker. He
lives with his wife and she supports him when he walks. His hobbies are reading mystery books
and watching TVs, and also, he is very organized and he likes to spend his time cleaning and
classifying trash.
He and his wife live in a small apartment, and their room is neatly organized but very narrow.
Since their room does not have much space, all the trashes are collected at the porch. He does
not use a trash bin, but instead, he hangs several plastic bags you receive at supermarket on the
porch. However, since he does not stand at the kitchen much, he does not take much care on the
garbage from the kitchen.
His ideal trash bin is a trash bin that has pedal to open the lid, and can classify the trashes inside.
Also since his house is very narrow, he wants a trash bin that fits at the corner of the room, and
also that allows the plastic bag from the supermarket to fit.
Observation 3
Gender: female
Age: 77 years old
She looks a lot younger than her age not only because of her looks, but also because she moves
quite actively. Her hobbies are shopping, stitching, knitting, and watching TV. She lives with
her husband in an apartment, and their room is quite narrow because there are many things in the
room.
She used to be a home economics teacher, so she loves to cook and stands at the kitchen
everyday. Since her room is very narrow, she sets a small garbage can that would fit inside the
sink. However, because it doesn’t have any lid, the smell spreads among the kitchen.
She is looking for a trash bin that would not take up much space and also that would prevent the
smell form spreading. She also wants a trash bin with a pedal because she does not want to
touch the trash while cooking.
User Scenario:
An old lady finishes drinking a bottle of water and decides to throw the bottle away in the trash
can in her kitchen. She hobbles towards the trash bin with her walking stick and pauses for a
moment before the bin. She carefully shifts her body weight on one leg, and reaches for the pedal
with the other leg in order to step on it and open the lid. For her, this seemingly simple task
requires a lot of effort to ensure that she does not fall. The lid opens as she presses down on the
pedal with much effort and force. She tosses the bottle in and notices that the bin is once again
full. She would use one leg to step in the bin and compress the trash. Unfortunately, that is now
beyond her balancing and stretching abilities. She moans that it is again time to take out the trash
and to refill the plastic bag in the bin. She decides to wait until her son comes to visit, and asks
him to take care of the trash instead. She lifts her foot off the pedal, and as the lid slams shut, she
smells the odor from the trash. Something as routine and mundane as throwing trash has become
something of a hassle and even danger for the elderly. Perhaps someone should redesign a trash
bin specifically suited for the elderly and handicapped to use.
30
APPENDIX C: Trash Bin Benchmarks:
Trash bin from Amazon.com.
Product Features
•
•
•
•
•
Hand-painted, interchangeable panels
Decorative panel slides into the front of
the frame
Handcrafted and finished with warm
wood tones
Drawer at the bottom
341/4"Hx163/4"Wx13"D
It has interchangeable panels so customer can match kitchen décor.
Also like what looks like a compartment area at the top?
Electronic Sensor Open Trash Bin
Hands full? The lid on this Stainless Steel
Trash Can opens automatically when you
approach!
Built-in motion sensor detects when you’re
within 8” in front, then opens the lid, and keeps
it open until you walk away. Perfect when
cleaning-off dinner-plate scraps! 12-gal.capacity inner bin holds a standard tall kitchen
trash bag (not included), and a retaining ring
keeps that bag neatly in place, easily removed
when full. “Off” switch prevents automatic
operation; two front buttons allow manual lid
operation. Four “D” batteries not included. 121⁄4”x16-1⁄8”x25-1⁄4” tall.
From http://www.improvementscatalog.com/default.asp
Like the auto open.
Note that it has an inner bin, with a bag retaining ring.
Can Crusher Trash Bin
31
Portable Can Crusher Solo (top part without bin) can be
mounted on the wall or carried to a trash centric event.
May be used on any flat surface. Unit not recommended
for crushing tin or steel food cans. Color of Solo may vary
from BLACK to GRAY, depanding on availability of
recycled plastic resin.
Size Dimensions
Capacity
Weight in lbs.
Composition
Usage
Key Features
Warranty
33" H x 14" W x 18.5" D
300 crushed cans
14 lbs. empty
high impact, heavy duty plastic
aluminum soda and beer cans
attractive, durable, large storage capacity
1 year manufacturer' warranty
http://www.composters.com/docs/recycling.html
Rubbermaid Kitchen Trash Can
o
o
o
o
Contours Bullet Wastebasket
$18
Plastic
Opening is Spring Loaded
32
Pros:
o
o
o
o
Cons:
o
o
o
o
Few Componets
Cheap
Covered
Bag fairly secured
Hand can touch trash
Bag may slip
Not aesthetically pleasing
Door flap can get dirty
Brabantia 336065 40 Liter
o Twin Garbage Trash Bin Matt Stainless Steel
o $236.95
o 15 lbs.
Brabantia's Twin Bins offer two separate and easily removable inner bins. Separate recyclable
and conventional waste. The Twin Bins are the very latest in elegant, easy and practical waste
collection. These bins are space saving and fit closely to the wall because of their flat-back
profile. The Twin Bin offers a unique 'soft touch' closing mechanism. One touch and the
dampened hinge will open the lid automatically and silently. Another push to shut it again.
Features:
o
o
Soft touch opening and closing mechanism
Flat back space-saving profile
33
o
o
o
o
o
o
Removable stainless steel lid
Removable inner bin for easy cleaning
Brabantia's 10 year guarantee
Shown above in matte steel
Shown below in stainless steel
Overall dimensions: 28.5" H x 11.5" W x 11.5" D
Rectangular Step Can 50L
o Made by Simplehuman
o $179.95
o Stainless Steel/Plastic
Pros:
o Rectangular shape fits = space efficient
o Lid locks up for “longer chores” (Opened by foot)
o Closes slowly & quietly (“damping technology”)
34
o Locks bag in well
o Wide pedal
Cons:
o Expensive
o Fingers may get pinched
o Must take out inner bin completely to insert new bag
35
Hailo 637009 - Trento Corner 23 Stainless Steel Trash Can
o $189
A new dimension to collecting waste: with Trento corner 23 in the practical triangular shape. The
space-saver of the waste bins fits in absolutely any corner. Perfect for the household and office.
Trento corner 23 combines an innovative design in high-grade stainless steel with maximum user
comfort, as the lid conceals a slow-motion mechanism. This closes the lid securely, gently and
almost silently. The wide base and non-slip knobs ensure a firm support.
Features:
o
o
o
o
o
o
o
o
o
Whisper lid closes gently and quietly
Two wing mechanism and internal pedal mechanism
Comfortable with ergonomically wide foot pedal
Wide base ensures particularly good stability
Removable inner bin made from black plastic
Fits into any corner and against the wall
5 year manufacture warranty
Capacity: approximately 6 gallons
Overall Dimensions: 22"H x 16"W x 14"D
36
And From Japan:
Pros:
Hook on side of bin
Multiple containers
Foot pedal opening
Cons:
Kind of blah
Only two internal containers
Pros:
Multiple containers
Two bins on top level
Cons:
Kind of blah
Manual opening operation
Pros:
Multiple containers
Two bins on top level
Cons:
Manual opening operation
No added counter space
37
Pros:
Multiple containers
Two bins on upper level
Cons:
Manual opening operation
Might be too tall?
38
APPENDIX D: Quality Function Development Chart (QFD)
39
APPENDIX E: Reverse Engineering description of Foot Pedal Type Trash Bin
Trash Bin #1
Ecco™ foot pedal operated lid trash bin with
integrated bag retainer.
For operation, the foot pedal is depressed and
opens the lid of the bin. The bag retainer keeps
the trash bag from falling off the top edge of the
bin (and thus does not allow trash to fall on top of
a collapsed bag).
The bag retainer (grey plastic part) is located on
back top edge of trash bin by the lid hinge.
The retainer flips up, so that user can slide the
bag into the clip; then folds down to hold bag in
place.
40
The bag retaining clip is a snap fit onto a hinge
pin. The hinge pin is molded into the bin base.
The foot pedal is on the front of the bin at the
bottom of the base.
Turning the bin upside-down the foot pedal
mechanism can be seen. The pedal is part of a
hinged linkage which pushes up and lifts the lid.
The pedal hinge has a pin (integral with the
plastic injection molded pedal) which rotates in a
pocket between the base and an enclosing piece
which is fastened in place to the base with two
threaded fastners.
41
Hooked to the back end of the foot pedal is a
vertical rectangular link
The top of the vertical link hooks into the lid with
a slide connection (slot) which allows the lid to
be ‘locked’ into the open position after the foot
pedal has been released. (cool huh!)
The connection between the foot pedal and the
vertical link allows for easy assembly because of
the kinematic joint.
42
Then the retaining clip for the pedal hinge can be
removed. This is the only part of the assembly
that requires threaded fasteners.
The foot pedal has now been removed from the
assembly, showing hinge pin.
Shown here are the foot pedal, the vertical link,
the hinge retaining clips and the bag retaining clip
from the assembly. Note the stiffening ribs on
the vertical link and the foot pedal components.
The manufacturer only stiffened these
components in a manner to prevent lateral
buckling as opposed to adding ribs to prevent
torsional distortion, because these components
were constrained in the assembly in such a way
that torsional bending would not be a problem.
43
Trash Bin #2
This bin is only slightly different from the first
bin, but is shown here to provide some
alternatives for meeting the team’s design criteria.
Note that this bin also uses a foot pedal to open
the lid.
This bin uses tabs on the lid to capture the bag in
place. The owner reported mixed results for this
mechanism.
This foot pedal linkage system didn’t capture the
links quite as much as the Ecco brand trash bin.
However, the linkages were fully captured at each
hinge point. This appears to make assembly more
difficult but did remove the need for adding
threaded fasteners to the assembly.
44
APPENDIX F: Initial Survey:
Describe where you live
A. Apartment
B. House
C. Studio
D. Dorm
E. Other __________
How many people use the kitchen? _____
Do you have pets?
YES NO
If so, what kind? ______________
How often do you cook?
A. Every Day
B. 1-2 times per week
C. Once every few weeks
D. Never
What kind of food do you cook? _________________________________________
Where is your kitchen trash bin currently located? ___________________________
What do you normally throw in your bin? (Circle all that apply)
A. Sharp Objects (i.e. glass, can lids, etc.)
B. Wet Objects (i.e. sauces, liquids, pulp, etc.)
C. Smelly Waste (i.e. meat, diapers, leftovers, etc.)
Do you separate plastics and newspaper/cardboard from your trash?
YES NO
How much trash do you throw out each week?
A. Less that one tall kitchen garbage bag per week
B. One tall kitchen garbage bag per week
C. Two tall kitchen garbage bags per week
D. Three or more per week
What features would you like your kitchen trash bin to have?
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
What bothers you about using your kitchen trash bin?
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
45
Rank these trash bin attributes in order of importance (1 = most important 6 = least important)
___Aesthetics
___Ease of use
___Ability to prevent odors
___Avoidance of old trash contact
___Ease of changing trash bag
___Size of bin
What shape of bin would you prefer?
A. Square
B. Rectangular
C. Cylinder
D. Oval
E. Triangular
F. Sphere
How big do you need your trash bin to be?
A. Volume of a backpack/paper grocery bag
B. Volume of a tall kitchen trash bin
C. Larger than a tall kitchen trash bin
Do you prefer to open your bin by using
A.
B.
C.
D.
E.
F.
your foot to press a pedal
your hand to push the lid
your hand to lift the lid
your hand to pull a lever
your finger to press a button
your hip to trigger an opening mechanism
Attributes: levels
Shape: square, rectangular, cylinder, oval, triangular, sphere
Volume: half of a bag, one bag, greater than one bag
Opening Mechanism: foot pedal, lid to lift, lever to pull, button to press, other
46
APPENDIX G: CAD Drawings
Alpha Prototype
Figure 12: CAD Drawing of Alpha Prototype:
47
Beta Prototype:
48
49
50
51
APPENDIX H: Schematic of Design Process:
Potential consumers (Elderly People, 55+)
1. Survey to determine
needs and wants of
potential users
Results of consumer wants
2. Determine the
important focuses of
design (QFD Chart)
Engineers
Marketing people
Manufacturing people
4. Marketing Analysis
6. Design
5. Manufacturing Analysis
3. Product Design
(Chosen Concept)
Engineers
Designers
9. Redesign
7. Product refinement
8. Market survey of
product
Users and
Producers
Engineers, Designers,
Marketing and Manufacturers 10. Final product
Input arrow
Feedback arrow
52
APPENDIX I: Gantt Chart
53
APPENDIX J: Engineering Analysis
Aluminum
Variables
Distance from End (closest to user) to Grip
Radius
Volume of Material
2.57E-02 m
1.20E-02 m
2.51E-03 m3
Constants
Height
Hypotenuse Length
Side Length
Force
Forces Applied to Sides (y)
Density
K (both ends fixed)
Elastic Modulus
7.12E-01
7.20E-01
4.95E-01
1.11E+03
5.56E+02
2.70E+03
4.00E+00
6.90E+10
m
m
m
N
N
kg/m3
1.01E+00 in
4.72E-01 in
1.95E+01 in
2.50E+02 lb
Pa
Equations
Moment of Inertia
1.63E-08 m4
Max Moment
-1.50E+01 N-m
Max Stress
1.11E+07 Pa
Critical Force
8.75E+04 N
Force on Vertical Beams (ends of hypotenuse) 1.08E+03 N
Force on Vertical Beam (vertex)
3.03E+01 N
Objective
Weight
Constraints
Stress
Force (column)
6.66E+01 N
<=
<=
4.00E+08 Pa
1.72E+05 N
Aluminum 1/8" Tubing
Variables
Distance from End (closest to user) to Grip
Outer Radius
Inner Radius
Volume of Material
1.27E-01
1.27E-02
9.53E-03
1.76E-04
m
m
m
m3
5.00E+00 in
5.00E-01 in
3.75E-01 in
54
Constants
Height
Hypotenuse Length
Side Length
Force
Forces Applied to Sides (y)
Density
K (both ends fixed)
Elastic Modulus
7.12E-01
7.20E-01
4.95E-01
1.11E+03
5.56E+02
2.70E+03
4.00E+00
6.90E+10
m
m
m
N
N
kg/m3
1.95E+01 in
2.50E+02 lb
1.25E+02 lb
Pa
Equations
Moment of Inertia
7.98E-11 m4
Max Moment
-8.87E+01 N-m
Max Stress
1.41E+10 Pa
Critical Force
4.29E+02 N
Force on Vertical Beams (ends of hypotenuse) 9.33E+02 N
Force on Vertical Beam (vertex)
1.79E+02 N
Objective
Weight
Constraints
Stress
Force (column)
4.66E+00 N
<=
<=
4.00E+08 Pa
4.29E+02 N
Steel 1/8" Tubing
Variables
Distance from End (closest to user) to Grip
Outer Radius
Inner Radius
Volume of Material
1.27E-01
1.27E-02
9.53E-03
1.76E-04
m
m
m
m3
Constants
Height
Hypotenuse Length
Side Length
Force
Forces Applied to Sides (y)
Density
7.12E-01
7.20E-01
4.95E-01
1.11E+03
5.56E+02
7.70E+03
m
m
m
N
N
kg/m3
5.00E+00 in
5.00E-01 in
3.75E-01 in
1.95E+01 in
2.50E+02 lb
1.25E+02 lb
55
K (both ends fixed)
Elastic Modulus
4.00E+00
2.00E+11 Pa
Equations
Moment of Inertia
7.98E-11 m4
Max Moment
-7.24E+00 N-m
Max Stress
1.15E+09 Pa
Critical Force
1.24E+03 N
Force on Vertical Beams (ends of hypotenuse) 1.10E+03 N
Force on Vertical Beam (vertex)
1.46E+01 N
Objective
Weight
Constraints
Stress
Force (column)
Oak
1.33E+01 N
<=
<=
Variables
Distance from End (closest to user) to Grip
Radius
Volume of Material
1.27E-01
2.14E-02
8.00E-03
Constants
Height
Hypotenuse Length
Side Length
Force
Force (y)
Density
K (both ends fixed)
Elastic Modulus
7.12E-01
7.20E-01
4.95E-01
1.11E+03
5.56E+02
7.50E+02
4.00E+00
1.10E+10
Equations
Moment of Inertia
Max Moment
Max Stress
Critical Force
Force on Vertical Beams (ends of hypotenuse)
Force on Vertical Beam (vertex)
1.65E-07
-8.87E+01
1.15E+07
1.41E+05
9.33E+02
1.79E+02
1.65E+09 Pa
1.24E+03 N
m 5.00E+00 in
m 8.43E-01 in
m3
m
m
m
N
N
kg/m3
Pa
m4
N-m
Pa
N
N
N
Objective
56
Weight
5.88E+01
Constraints
Stress
Force (column)
<=
<=
N
5.50E+06 Pa
1.72E+05 N
Aluminum 1/4" Tubing
Variables
Distance from End (closest to user) to Grip
Outer Radius
Inner Radius
Volume of Material
1.27E-01
1.27E-02
6.35E-03
7.04E-04
m 5.00E+00 in
m 5.00E-01 in
m 2.50E-01 in
m3
Constants
Height
Hypotenuse Length
Side Length
Force
Forces Applied to Sides (y)
Density
K (both ends fixed)
Elastic Modulus
7.12E-01
7.20E-01
4.95E-01
1.11E+03
5.56E+02
2.70E+03
4.00E+00
6.90E+10
m
m
m 1.95E+01 in
N 2.50E+02 lb
N 1.25E+02 lb
kg/m3
Equations
Moment of Inertia
Max Moment
Max Stress
Critical Force
Force on Vertical Beams (ends of hypotenuse)
Force on Vertical Beam (vertex)
1.28E-09
-8.87E+01
8.82E+08
6.86E+03
9.33E+02
1.79E+02
Objective
Weight
1.86E+01
Constraints
Stress
Force (column)
<=
<=
Pa
m4
N-m
Pa
N
N
N
N
4.00E+08 Pa
6.86E+03 N
57
APPENDIX K: Environmental Impact Analysis
Material Cycle (MC) |
Energy Use (EU)
|
Toxic Emissions (TE)
(input/output)
(input/output)
(output)
____________________________________________________________________________
Production and supply of all materials and components
MC – Wood and tile are renewable, plastic and aluminum should be chosen to be
recycled/recyclable
EU – Transport of wood to manufacture, prep of wood for manufacture, manufacture of tile,
plastic pellet manufacture (or for recycling, grind/clean/drying process), manufacture of
aluminum components
TE – Plywood gluing, metal brackets during manufacture, anodizing of aluminum parts
____________________________________________________________________________
In-house production
MC – Waste from production of wood, plastics and tile
EU – Prep of wood during manufacture, cutting tile to shape
TE – Plastic production of bins, grout and glue of tiles into place
____________________________________________________________________________
Distribution
MC – None
EU – Transport of cabinets, trolleys and bins (reduce by providing units in kit form)
TE – None
____________________________________________________________________________
Use:
MC – None
EU – None
TE – None
____________________________________________________________________________
End-of-Life system:
• recovery
MC – The plastic and aluminum components can be recycled
EU – Melting of aluminum during recovery, grind and process of plastics during recycling
TE – Anodized coating on aluminum components will be released during recycle process
• disposal
MC – Wood products can be reused or disposed of
EU – Chipping or other disposal process of wood parts and casters
TE – Emissions during transport and disposal of non-recycled parts
58
APPENDIX L: Kansei Analysis
Kansei Survey
Please assign each characteristic a number -2 -1 0 1 2
-2 represents the least, 2 represents the most, and 0 would indicate a neutral perception
Cabinet
Color of side – wood / white
Type of edges – sharp / rounded
Color of counter top – maroon / white
Color of
side
Type of
Edges
Wood
Wood
Wood
Wood
White
White
White
White
Sharp
Rounded
Sharp
Rounded
Rounded
Sharp
Rounded
Sharp
Color of
counter
top
Maroon
Maroon
White
White
Maroon
Maroon
White
White
Cleanliness
Convenient to
use
Durability
Aesthetics
Trolley
Design of handles – straight / rounded
Handle material – rubber / plastic
Color of frame – brown / metallic
Design of
handles
Straight
Straight
Straight
Straight
Rounded
Rounded
Round
Rounded
Handle
material
Rubber
Plastic
Rubber
Plastic
Plastic
Rubber
Plastic
Rubber
Color of
frame
Brown
Brown
Metallic
Metallic
Brown
Brown
Metallic
Metallic
Stability
-not tipping
Strength
Convenient
-max. load to use
Cleanliness
59
Results
Cabinet
Color of side Edge type
Wood
Sharp
Wood
rounded
Wood
Sharp
Wood
rounded
White
rounded
White
Sharp
White
rounded
White
Sharp
counter color Cleanliness Convenient to use Durability Aesthetics
maroon
-0.25
-0.75
0
0.25
maroon
0.25
1.25
1
1.25
white
0.25
-0.25
1
-0.5
white
1
1.25
0
1.25
maroon
1
1
1.25
1
maroon
-0.25
-0.5
0.25
-0.75
white
1.75
0.75
0
0.25
white
1.25
-1
-1.5
-0.5
Trolley
handle design
straight
straight
straight
straight
rounded
rounded
rounded
rounded
handle material
rubber
plastic
rubber
plastic
plastic
rubber
plastic
rubber
frame color stability strength convenient to use cleanliness
maroon
1
1.5
0.75
-0.75
maroon
1.25
1.25
0.25
0
metallic
1.75
1.75
1.25
1.25
metallic
1.25
1.5
0.75
1.75
brown
0
0.75
0.25
-0.05
brown
-0.25
0.75
0.25
-1
brown
0
1.25
0.75
0.25
brown
0.5
1.5
1
0
Values assigned to each characteristic value for our regression line calculation
characteristic
values cabinet
wood
white
-1
characteristic
values trolley
straight
sharp
1
round
-1
maroon
1
white
-1
1
rounded rubber plastic brown
metallic
-1
1
-1
1
-1
1
60
APPENDIX M: Economic Analysis
Deriving Demand function Q
We initially assume the 3 design attribute are at what we consider the satisfactory quantity. This
means most consumers will consider any improvements from this amount making the attribute
overall positive, and any decrease in the amount will make the attribute overall negative.
•
•
•
Volume = V = 1 m3
Strength (of trolley)= S = 45N
Weight (of trolley) = W = 30N
Assuming that Q {P, V, S, W} = Θ – aP + bV + c S + dW
Where Θ, a, b, c and d are constants.
The constant are calculated out using simultaneous equations based on the assumptions as shown
below from left to right.
Holding
Constant
Varying
Assume
Result
Comments
VSW
SWP
VWP
VSP
PΘ
P=$120,Q=100
P=$80 ,Q=200
Θ = 400
a = 2.5
Assume average
price people
willing to pay is
$100 based on
existing market
research
VQ
V =0.5, Q=50
V=2, Q=300
b=140
SQ
S=80, Q=300
S=10, Q=150
c=5
WQ
W=5,Q=150
W=1, Q=300
d= -75
Q decreases
more when V
decreases, than
Q increases
when V
increases
Q increases
more when S
increases,
than Q
decreases
when S
increases
Q increases
more when W
decreases,
than Q
decreases
when W
increases
Deriving V, S and W functions
V is simply determined by the space enclosed by the trolley frame
S is determined by assuming that failure will be due to buckling in the vertical components in the
trolley frame. We Use Euler’s buckling strength to calculate the total strength the combine
vertical components of the frame can withstand
W is determined by calculating the total volume of the trolley frame based on its component
lengths and diameters. The wheels and linkages (2.5N) are then added to the weight of the frame.
Deriving the Total Cost (Variable + Fixed cost)
61
The variable cost is a function of the material cost of the trolley frame, the cabinet surface and
the counter top. The total length of the trolley frame components is multiplied by the cost of the
material chosen. The cost of the cabinet surface and counter top is calculated by the
multiplication of the total surface area with the cost of the material for the cabinet surface and
counter top respectively.
The fixed cost is the sum of:
• The labor hours involved (3 man hours at $7 per hour per bin)
• The rental of machinery divided by Q $8
• Factory floor rental divided by Q $6
• Additional parts (wheels, handle, linkages and plastic bin) $5
Deriving the profit equation
The profit equation is hence:
Π = Re venue − Total .Cost
Π = P ⋅ Q − Q ⋅ Cost / item
And using the information derived above,
⎡
⎤
⎢($
⎥
/ m ) ⋅ 2 ⋅ LT + H T + 2 2 ⋅ LT +
⎢ material .trolley
⎥
2
⎢
⎛
⎞⎥
L
Π = P ⋅ [400 − 2.5 ⋅ P + 140 ⋅ V + 5 ⋅ S − 75 ⋅ W ] − Q ⋅ ⎢($ materia.cabinet .exterior . / m 2 ) ⋅ ⎜⎜ 2 ⋅ LC H C + C
⎟⎥
2 ⎟⎠⎥
⎢
⎝
⎢
⎥
2
⎞
⎢ $ material .choice.counter .top / m 2 ⋅ ⎛⎜ LC
⎥
+
40
⎟
⎜
⎢⎣
⎥⎦
2 ⎟⎠
⎝
(
(
)
)
Where V, S and W are defined in the economic analysis part of the main paper.
62
APPENDIX N: CBC Survey-Sample
What demographic group do you belong to?
•
•
•
Student (if so, answer questions as if you are purchasing for your parents/grandparents)
Eligible to belong to AARP (Association for the Advancement of Retired People)?
Everyone else. (Answer questions as if purchasing for parents)
This product consists of a cabinet which houses a trolley with three bins for trash and
recyclables. What material would you like the cabinet exterior to be made of?
•
•
•
•
•
Stainless Steel
Plastic Laminate
Oak
Birch
Other ________________________________
What material would you prefer the cabinet top to be made of?
•
•
•
•
Laminate Top
Butcher Block Top
Tile Top
Stainless Steel
When taking the trash out, would you want to be able to use the trolley as a walker?
•
•
Yes
No
When adding the cabinet to your kitchen, what is the most important consideration you have?
•
•
•
•
Cleanliness
Utilitarian
Subtlety
Ecologically Progressive
What word would be the most important way of describing the trolley?
•
•
•
•
•
Stable
Cool Looking
Sophisticated
Functional
Durable
This section of the survey was followed by 6 variations of the following question sets:
63
If these were your only options, which would you choose?
Choose by clicking one of the buttons below:
Plastics
Recyclables
= enough to
fill a paper
grocery bag
Plastics
Recyclables
= 2 gallon
milk
cartons,
couple soup
cans
Plastics
Recyclables =
1 gallon milk
carton, couple
soup cans
Regular
Trash =
Plastic
grocery bag
Regular
Trash =
Paper
grocery bag
Regular
Trash =
Office trash
bin trash bag
Price = $60
to $79
Price = $80
to $99
Price = $100
to $119
Recycled
Papers =
one
semester's
worth of
ME455
Lecture
Notes
Recycled
Papers =
one week's
worth of
Michigan
Daily
Recycled
Papers = one
week's worth
of Ann Arbor
Newpapers
Wt of
Trolley = 1
gallon of
milk
Wt of
Trolley = 3
gallons of
milk
Wt of Trolley
= 2 gallons of
milk
Trolley will
only hold
trash
Trolley will
handle
being
leaned on
lightly
Trolley will
support
weight of
Professor
Papalambrous
NONE: I
wouldn't
choose any
of these.
64
APPENDIX O: Four Level CBC Survey Betas as Extracted From Sawtooth Program
1
0.73677
0.12054
-0.36628
-0.29098
p
z1
z2
z3
part worths
2
0.31944
-0.12441
-0.00042
-0.08751
3
-0.42274
0.00387
0.28453
-0.17183
4
-0.63348
0
0.08217
0.55032
Note* The part worths above in bold italics were varied while keeping the 1st column constant to
maximize ∑LL
att
p
z1
z2
z3
p
z1
z2
z3
p
z1
z2
z3
p
z1
z2
z3
p
z1
z2
z3
p
z1
z2
z3
p
z1
z2
z3
p
z1
level
1
1
Part worth utility
2
3
4
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
exp(u)
choice
%predicted %observed calc LL
0.73677
-0.12441
0.28453
0.55032 1.44721 4.251237
0.31944
0.00387
0.08217
-0.29098
0.1145 1.121313
-0.42274
0.00387
-0.36628
-0.08751 -0.87266 0.417839
-0.63348
0.12054
-0.00042
0.55032 0.03696 1.037652
0.73677
0.12054
-0.00042
-0.08751
0.31944
-0.12441
0.28453
-0.17183
-0.42274
0.00387
0.08217
0.55032
-0.63348
0.00387
62.26146
60 -12.3468
16.42217
15 -19.1188
6.119452
10 -12.1329
15.19692
15 -12.2737
0.76938 2.158428
42.88511
40 -14.7077
0.30773 1.360334
27.02803
30 -17.0456
0.21362 1.238152
24.60045
25 -15.2264
65
z2
z3
p
z1
z2
z3
p
z1
z2
z3
p
z1
z2
z3
p
z1
z2
z3
p
z1
z2
z3
p
z1
z2
z3
p
z1
z2
z3
p
z1
z2
z3
1
1
-0.36628
-0.29098 -1.28687 0.276134
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
0.31944
-0.12441
-0.00042
-0.17183 0.02278
-0.42274
0.00387
0.08217
0.55032 0.21362
-0.63348
0.12054
-0.36628
-0.29098 -1.1702
-0.42274
0.00387
0.28453
-0.08751 -0.22185
5.486413
5 -6.30356
1.023041
30.3345
30 -15.5419
1.238152
36.71281
40 -17.4073
0.310305
9.200942
10 -10.3617
0.801036
23.75174
20 -12.4861
13.96429
15 -12.8247
24.39562
25 -15.3172
11.84912
10 -9.26314
49.79097
50 -15.1425
-0.63348
0.00387
-0.00042
-0.29098 -0.92101 0.398117
-0.42274
-0.12441
-0.36628
0.55032 -0.36311 0.69551
-0.42274
-0.12441
-0.36628
-0.17183 -1.08526 0.337814
0.31944
0.12054
0.08217
-0.17183 0.35032 1.419522
∑ LL
66
APPENDIX P: CBC System Multinomial Logit Estimation
Copyright 1993-2004 Sawtooth Software
Name/Description: Logit Run
10:17:59AM Saturday, December 02, 2006
Main Effects
Tasks Included: All Random
Total number of choices in each response category:
1 48 28.57%
2 55 32.74%
3 42 25.00%
NONE 23 13.69%
Files built for 28 respondents.
There are data for 168 choice tasks.
Iter 1 Chi Square = 68.79912 rlh =
0.30681
Iter 2 Chi Square = 69.48703 rlh =
0.30744
Iter 3 Chi Square = 69.48731 rlh =
0.30744
Iter 4 Chi Square = 69.48731 rlh =
0.30744
Converged.
Log-likelihood for this model = -198.15380
Log-likelihood for null model = -232.89745
-----------Difference = 34.74365
Percent Certainty
= 14.91800
Consistent Akaike Info Criterion = 494.29102
Chi Square
= 69.48731
Relative Chi Square
=
4.34296
Effect
Std Err
t Ratio Attribute Level
1
0.73677
0.15390
4.78728 1 1 Price = $60 to $79
2
0.31944
0.15457
2.06665 1 2 Price = $80 to $99
3
-0.42274
0.18568
-2.27675 1 3 Price = $100 to $119
4
-0.63348
0.19783
-3.20214 1 4 Price = $119 to $140
5
6
7
0.12054
-0.12441
0.00387
0.12562
0.13362
0.13069
0.95956 2 1 Wt of Trolley = 1 gallon of milk
-0.93113 2 2 Wt of Trolley = 3 gallons of milk
0.02961 2 3 Wt of Trolley = 2 gallons of milk
8
-0.36628
9
-0.00042
10
0.28453
Papalambrous
11
0.08217
0.18026
0.16548
0.15730
-2.03198 3 1 Trolley will only hold trash
-0.00255 3 2 Trolley will handle being leaned on lightly
1.80887 3 3 Trolley will support weight of Professor
0.16614
0.49459 3 4 Trolley will support weight of Shaquille O'Neal
67
12
-0.29098
0.17484
13
-0.08751
0.16929
14
-0.17183
0.17212
15
0.55032
0.15417
16
0.14816
0.12713
Arbor Newpapers
17
-0.03313
0.12848
Michigan Daily
18
-0.11503
0.13159
ME455 Lecture Notes
19
-0.06147
0.13168
couple soup cans
20
0.16949
0.12494
couple soup cans
21
-0.10802
0.13232
grocery bag
22
-0.56663
0.23057
-1.66426
-0.51694
-0.99831
3.56947
1.16550
4 1 Regular Trash = Plastic grocery bag
4 2 Regular Trash = Paper grocery bag
4 3 Regular Trash = Office trash bin trash bag
4 4 Regular Trash = Tall kitchen trash bag
5 1 Recycled Papers = one week's worth of Ann
-0.25788 5 2 Recycled Papers = one week's worth of
-0.87420 5 3 Recycled Papers = one semester's worth of
-0.46682 6 1 Plastics Recyclables = 1 gallon milk carton,
1.35666 6 2 Plastics Recyclables = 2 gallon milk cartons,
-0.81637 6 3 Plastics Recyclables = enough to fill a paper
-2.45755 NONE
Elapsed time: 0:00:00
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