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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