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Project LAPSUS: Sit-to-Stand DeviceJoan I. García Torres, Manuel J. Pérez-Vargas, Nicole Méndez, Grexarie Torres
Advisor: Mayra MéndezUniversity of Puerto Rico, Mayaguez
The first phase is the inspiration phase, more commonly known or referred to as
HEAR. (Design Kit, 2016) In this phase the main task is acquiring information
from the targeted community. This can be achieved through numerous activities
such as interviews, in-context immersion, observation, research and so on.
(IDEO.org) Once all of this information is gathered then the next phase is the
Ideation phase or the CREATE phase. In which the gathered information serves as
the baseline from which the actual problems, opportunity areas and ideas are
extracted. Last but not least is the Implementation phase or DELIVER, in which
the proposed solution is developed to its fullest extent. (IDEO.org) Once every
phase is complete, this solution will become a marketable product that, since it
originated from the needs of a community, will aid in solving the needs of the
customers and prove to be a great success. (Design Kit, 2016)
AbstractProject LAPSUS is a research project based on helping adults with mobility
problems on daily tasks. The first task in completing this project was to establish
the tasks that require assistance, to do this, the Design Thinking Methodology was
used. The team interviewed various patients and their caretakers to establish their
needs and completely understand the design requirements. Once these interviews
were completed the team could establish a list of needs and a list of possible
solutions to these problems.
The team decided to construct a product that would help people with mobility
problems to sit and/or stand up while decreasing possible injuries to the caretaker.
Although similar products are in the market they are expensive, may require
electronic assistance and/or require the patient to possess great strength in their
upper body. This design is different because it allows the user to sit or stand
without exerting much upper body strength while being cost effective enough to
be available to patients of diverse financial status.
In total three different prototypes were created. Each prototype varied in aspects
of the design like ergonomics, cost effectiveness, possibility to manufacture and
how the forces are distributed. The final design took into consideration
constructive inputs of prototypes I & II and all positive features were
incorporated. The product analysis consisted of free body diagrams evaluations,
solidworks finite element analysis and biomedical evaluation to ensure the safety
handling of users. The product is found to be competitive in the market and meets
the requirements established for the success of the project.
Figure 1: The Hear, Create, Deliver phases of the IDEO Design Thinking process (IDEO.org)
Theoretical BackgroundHuman-Centered Design is a creative approach to problem solving. This process
begins by getting to know the people or community a team is designing for,
identifying problems and solving them with new innovative solutions. The unicity
of this process is that it is all about building deep empathy with the people a team
is designing for. In doing so, the designers are able to generate ideas, concepts and
solutions closely related to the problem at hand. Human-Centered Design consists
of three (3) phases.
Create
3. Brainstorm New Solutions
After choosing the opportunity areas, the team went to on to generate thirty
(30) different ideas that could help cater to the selected opportunity area. The
idea had to comply with the following criteria: feasibility, reality, low
complexity, manufacturability, low cost, practicality and community impact.
After generating all the ideas for each opportunity area, the team discussed
each idea and selected the idea displayed below.
4. Make Ideas Real
The selected idea consists of a product capable of helping the user sit and
stand with the help of a caretaker. This, in turn, yields two main objectives.
First, that the product is capable of lessening the amount of stress a caretaker
takes into his or her body at the moment of helping a patient to a sitting or
standing position. Second, to lessen the impact stress that the patient’s body
receives when sitting, given that most patients throw themselves onto the seat
or the caretaker is unable to support their weight when lowering them. Taking
into account all of these objectives, the team developed a Concept Model. The
model features a system that is completely mechanical and through mechanical
advantage, reduces the force a caretaker exerts when sitting or standing a
patient. The Concept Model is displayed below.
Design
Figure 4: Concept Design
Create
1. Share Stories – Obtain Insights – Identify Patterns
Having every piece of individual information, the team was able to identify the
patterns that emerged throughout the different observations made during the
interviews.
For this, the team extracted key insights with the relevant and individual
information acquired in the previous step. With the key insights, the team
proceeded to divide the information into different themes that will serve as a
method of exploring the commonalities, differences, and relationships between
the information.
2. Create Opportunity Areas
Creating opportunity areas is the process of translating insights into
opportunities. It is about moving from the current state to envisioning future
possibilities. It should be noted that opportunity areas are not solutions, it
suggests more than one solution. It allows the team to create many solutions.
Opportunities start with the phrase “How might we...?” to suggest a mindset of
possibility (Design Kit, 2016). The team created nine (9) opportunity areas of
the fourteen (14) themes that were generated with the acquired information.
Ultimately, the team aligned on pursuing the opportunity area below.
Opportunity Area:
• How can we help patients sit and stand adequately and pain-free?
Design Directive:
• Help me sit/stand correctly and pain-free.
Insight:
• When sitting, people often throw themselves into a sitting position
because they lack the strength to sit appropriately.
Methodology
ReferencesDesign Kit. (June 26th, 2016). What is Human-Centered Design? Obtained from
Design Kit: http://www.designkit.org/human-centered-design
IDEO.org. (s.f.). Human-Centered Design Toolkit - Second Edition. IDEO.org.
National Science Foundation. (June 26th, 2016). General & Age-Related
Disabilities Engineering. Obtained from National Science Foundation - Where
Discoveries Begin:
http://www.nsf.gov/funding/pgm_summ.jsp?pims_id=501021
Design:
http://www.matweb.com/search/datasheet_print.aspx?matguid=67d8cd7c00a04ba2
9b618484f7ff7524
Barrier Free Lifts, Inc. Ocala, FL USA. "Standard patient lift slings | Barrier Free
Lifts - Patient Handling Equipment." Standard patient lift slings | Barrier Free Lifts
- Patient Handling Equipment. N.p., n.d. Web. 10 Mar. 2017.
<http://www.barrierfreelifts.com/en_standard-patient-lift-slings.php>.
Bohannon, R. W. (2015). Daily sit-to-stands performed by adults: a systematic
review. Journal of Physical Therapy Science, 27(3), 939–942.
http://doi.org/10.1589/jpts.27.939
Discount Medical Supplies From People Who Care. (n.d.). Retrieved May 20,
2017, from http://www.rehabmart.com/
Bulea, T. C., & Triolo, R. J. (2012). Design and Experimental Evaluation of a
Vertical Lift Walker for Sit-to-Stand Transition Assistance. Journal of Medical
Devices, 6(1), 14504–NaN. http://doi.org/10.1115/1.4005786
"Machine Design." Machine Design: LESSON 29 DESIGN OF LEVERS. N.p.,
n.d. Web. 10 Mar. 2017.
<http://ecoursesonline.iasri.res.in/mod/page/view.php?id=125538>.
Xu, Y., A. V. Terekhov, M. L. Latash, and V. M. Zatsiorsky. "Forces and moments
generated by the human arm: variability and control." Experimental Brain
Research223.2 (2012): 159-75. Web.
<https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3501382/>.
At the start of the project and initial evaluation of the product, the work load
seemed to be a low one, with few iterations and a straight forward objective. It
was not until we started with the pre-design activities that the full view and
aspects of the things that needed to be considered was truly seen. This product is a
complex one, where the safety and health of two people, user and caretaker, need
to be taken into consideration. Throughout the design analysis, different iterations
and prototypes of the product were fabricated. In the product development section,
the dimensions of the metal bars, the material, type of bar unions – welding,
screws, etc. –, mesh hooks, and other things were analyzed and evaluated for
failure. This allowed us to generate a final design capable of withstanding the
forces we were designing for. When evaluating the product with different people
of different ages, it was proven that the product fulfills it’s purpose of lifting and
sitting a person the safest way possible and with the least amount of pain.
However, some limitations are that the product was withstand 220lbs, it’s heavier
that expected and it’s not completely portable, but it has felt pads that helps the
user slide the product easier.
Conclusions
Adhering to the steps outlined in the IDEO Human Centered Design method, the
team generated and gathered relevant information as described below.
Hear
1. Identify a Design Challenge
In order to identify the design challenge, the team gathered existing
information about the struggles that individuals with any type of disabilities
and transformed the information into several action items that were framed in
human terms. After generating numerous amounts of design challenges, the
team chose to pursue the following design challenge:
How can we improve the mobility of adults with disabilities?
2. Identify people to speak with
Recruiting appropriate and inspirational participants was critical. Attention to
gender, ethnicity, and class balance was also crucial for the research. The team
divided the participants intro three (3) categories: Experts, Caretakers and
Patients.
3. Interview
The individual interview guide was made considering three (3) sets of
questions, which are:
• Open Specific – Age Range, Race, Sex, Income Range, Occupation.
• Go Broad – Patients share their everyday stories.
• Probe Deep – Focused on the Design Challenge.
Figure 2: Share stories – Individual Information
Final DesignTo further evaluate the product and ensure its safety the team recorded people,
pertaining to the 5th, 50th and 95th percentile in height for females and males,
interacting with the product. This allowed them to study how much of the
population would be able to use the product. In the experiments, it was found that
all the subjects could complete the movement safely, and they paid close attention
to what would be characterized as a critical case such as a 5th percentile female
lifting a 95th percentile male or female. In both cases the movement could be
completed safely, although, in the case of lifting the 95th percentile male, the
caretaker experienced some wrist pain if the movement was done repeatedly, but
they could perform the movement safely. This evaluation is shown in Figure 5 in
which we can confirm that the risk in this movement is to both the wrist and the
elbow, though both are still in safe percentages.
Figure 8: 3DSSPP Results for 5th percentile caretaker
lifting 95th percentile female
Ergonomic Analysis
Cost AnalysisFor this product, the analysis was performed using the total cost of material & the
actual cost of material that was used to manufacture the product. This analysis is
composed of two parts: Total & Overhead costs and Actual Product Cost. Total &
Overhead costs include everything that was involved in the making of the product
but did not make it to the final prototype. The retail price for the final prototype
was set to four (4) times the manufacturing cost. This is due to our competition
being in the near &7,000 and we want to be competitive with out numbers. Total
costs are shown in the table below.
To increase sales in September, another welder would have to join the team.
Having another welder will ensure that the months following September will have
enough product to satisfy the demands. The following MPS demonstrates how
production would work if there are two welders instead of one:
Table 3: Master Production Schedule (MPS) with TWO (2) Welders
Production Analysis
Month Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
Forecast 4 4 6 8 8 10 10 12 12 12 12
Availabl
e35 31 30 27 24 19 14 7 5 3 1
MPS 39 5 5 5 5 5 5 10 10 10 10
"On
Hand"35
Month Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
Forecast 4 4 6 8 8 10 10 12 12 12 12
Availabl
e35 31 30 27 24 19 14 7 0 -7 -14
MPS 39 5 5 5 5 5 5 5 5 5 5
"On
Hand"35
Amount
Total Cost of Materials $807.05
Actual Cost of Materials & MFG $500.47
Retail Price (4X MFG Cost) $2,001.88
Figure 3: Sit/Stand Assist – Selected Idea
Future Works
Software:
Simulation Platform: Autodesk Fusion 360
CAD Model Software: SolidWorks
The following is a summary of the Finite Element Analysis study using Autodesk
Fusion 360 software.
Study Report
Study Properties
Study Type Static Stress
Last Modification Date 2017/04/24, 00:19:55
General
Contact Tolerance 0.001 in
Remove Rigid Body Modes No
Materials
Component: Full Product Assembly
Material: Steel, Cast
Safety Factor: Yield Strength
Density 0.2836 lbmass / in^3
Young's Modulus 3.046E+07 psi
Poisson's Ratio 0.3
Yield Strength 36259 psi
Ultimate Tensile Strength 43511 psi
Thermal Conductivity 6.019E-04 tu / (s in F)
Thermal Expansion Coefficient 6.667E-06/ F
Specific Heat 0.1146 Btu / (lbmass F)
Contacts
Bonded/Welded
Mesh
Type: Solids
Nodes: 165575
Elements: 90881
Loads
Free Body Diagram
Forces:
FC = 64 lbf
FL = 128 lbf
FH = 150 lbf
Results
Safety Factor
The final product is a result of the collective research and tests executed by the
design team. Following the prototypes, the design was made per the constraints.
Therefore, the team reviewed the available materials at local stores such as Steel
and Pipes, Home Depot, and Granger. Upon review of the materials, the team
selected the Steel and Pipes store due to the large availability of steel pipes of
square and circular cross section. Figure 7 shows the Final design rendered and a
picture of the actual final prototype.
Some future improvements that could be added are integrated wheels with
industrial grade brakes placed inside the 2X4 metal tube base. This would help to
make the product more mobile, while at the same time maintaining the product
safe and stable. Also, if wheels and a locking mechanism for the pivot/handles
were installed this would mean that the product could be modified to be able to
transport a person at dead weight. A future recommendation for the product is to
decrease the weight of the product by utilizing lightweight but strong materials
that could substitute the black steel used in the final design manufacturing.
Sponsored by: National Science Foundation (NSF) Award No. CBET-1403753
One of the things the team evaluated was the marketability of their product, they
realized that they would be selling Business-to-Business and this meant that,
although manufacturing cost was approximately $500.47 per unit, the team should
sell their product at a much higher price, around $2,000 being the suggested price.
This is because the price for the competitor is approximately $7000.00 and having
a price too low could influence probable buyers’ confidence in LAPSUS-STS.
With the data obtained from the Cost Analysis, the team decided to evaluate the
possibility of mass producing the LAPSUS Sit-and-Stand device. Using the
Breakeven Formula listed below, it was determined that (3) units are required to
break even. Furthermore, the production cycle of their closest competitor was
studied and the team determined that they needed to produce twelve (12) units
every month. The Master Production Schedule (MPS) was created based on this
data and the assumption that the lead time required for each unit was twenty (20)
hours, having only one (1) welder. With this information, only five (5) units of the
product can be produced each month, although it is expected to be able to increase
by September. To keep up with the sales, production would have to start in July
(of the year before) due to the need of having thirty-five (35) products “on Hand”
by the start of the year.
Table 2: Master Production Schedule (MPS) with ONE (1) Welder Figure 7: Final Design Rendering (Left) & Actual Product (Right)
FC
FL
FH
Final Design Model
Finite Element Analysis
Figure 5: Free Body Diagram
Figure 6: Free Body Diagram
Table 1: Total Amounts of Cost Analysis