p14006 bath tub lift phase ii reviewedge.rit.edu/content/p14006/public/msd14006 phase iii...
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P14006 Bath Tub Lift Phase III Review Amos Baptiste Jeremy Czeczulin Andrew Hughes Richard Prilenski
Introductions
Name Major/Role
Amos Baptiste Industrial & Systems Engineer/Team Leader
Jeremy Czeczulin Mechanical Engineer
Andrew Hughes Mechanical Engineer
Richard Prilenski Mechanical Engineer
Agenda
• Phase II Overview
• Problem Definition
• Customer & Engineering Requirements
• Action Items
• Benchmarking
• Concept Selection
• Design Schematics
• Electrical & Mechanical Architecture
• Von Mises Stress Analysis, Displacement, and Factor of Safety
• Ergonomics
• Bill of Materials
• Project Plan (Week 9-12)
• Team Assessment
Problem Statement
• Bathtub lift – a device that provides assistance to an individual with physical disabilities, including limited balance, coordination, or mobility
• Can reduce the difficulties of raising and/or lowering an individual into the tub by utilizing a powered seat and a simple control module
• As population grows the number of aged individuals will greatly increase making demand for assist devices increase
• Project motivation – Theresa Loce
• Improve the current design
• Current device does not meet her needs
• Powered lift that is sturdy, comfortable, easy to use/clean, makes minimal noise, and takes into account physical limitations of user
• Ultimate goal – user maintains autonomy and privacy
Deliverables
• Effectively assist the user for bathing purposes
• Device is easy to access from starting position
• Minimized operating time
• Provide a comfortable and supportive seating area
• Accessible to 10th-70th percentile for both genders, regardless of age
• Reasonably lightweight and portable, able to be transported
Current and Desired State
Current
• Unstable
• Out of production
• Damaged
• Difficult access
• Obstructions prevent full use
Desired
• Easy use
• Easy access
• Portable
• Lightweight
Stakeholder(s)
• Primary Customer: Theresa Loce
• Contact: 585-647-2329
• Secondary Customer (s): Wheel chair users/handicap public & Elizabeth DeBartalo, Hospitals (RGH), Nursing Homes, suppliers/vendors, & individuals recovering from knee surgeries.
• Contact: [email protected]
• Faculty Guide: Art North
• Contact: [email protected]
• Sponsor (financial support): RIT & Theresa Loce
Benchmarking
Company Bathmaster Sonaris Bellavita Orca Portable Water Power P14006
Type Battery Battery Battery Hydraulic Battery
Number of Lifts 8 to 10 N/A 12 Infinite 12-Oct
Time to charge 3 hours N/A 6 hours 0 hours <= 4 hours
Weight Capacity 308 lbs 300 lbs 400 lbs 200 lbs >=150
Weight of device 15.75 lbs 20.5 lbs 35 lbs 19 lbs 20-30 lbs
Arm rest No No No Yes Yes
Portable Yes Yes Yes Yes Yes
Recline angle 40 degrees 50 degrees 0 degrees 0 degrees 40-90 degrees
Rotate angle 0 degrees 0 degrees 0 degrees 360 degrees >=180 degrees
Lifting Height 3"-18" 2.3"-18.8" 17" 2"-21" TBD
Back rest dimensions 24" x 14" 25.1" H x12.5"-14.1"W 26" x 27" 15" x 15" TBD
Seat dimensions 20" x 15"; 27" with flaps 22.4"L x 12.7"W;27.5" with flaps 14.75"W x 19"D N/A TBD
>= 18”
25” x 15” 17” x 15”
10-12
Action Items from Wk 6-9
ID Action Items Owner Status Notes
1
Create drawing from 3D models of bathroom and devices having multiple
designs Andrew H. Completed
2 Use ANSYS or other finite element analysis program to test 3D models Andrew H. Completed Was completed in Inventor instead of ANSYS
3 Create ergonomics drawings based on engineering/customer requirements Amos B. Completed Met with Dr. Marshall for review
4 Create a budget and propose it to Art based on bill of materials Amos B. Completed
5 Refine functional decomposition Team Completed Highlighted the function to focus on
6 Plan or conduct a design of experiment for the bath tub lift Amos B. In progress Consider purchasing actuator
7 Create a Bill of Materials Richard P. Completed Rough draft and may be changed overtime
8 Conduct stress analysis on CAD drawings Richard P. Completed
9 Calculate the power necessary to power Jeremy C. Completed Met with Dr. West for review and EE's
10 Update and narrow down concept drawings of project (hand-drawn) Jeremy C. Completed
11
Specify the requirements of parts of the device (battery voltage, steel rating,
etc.) Jeremy C. Completed Met with Dr. Boedo
12 Relearn the basics of Creo Parametric; if needed, learn Autodesk Inventor Jeremy C. In progress May not be needed with the usage of Inventor
13 Make any necessary changes to existing documents or pages Team In progress Need to update documents on Edge
Electrical vs Hydraulic Design
• Pro’s
• Easier use (automated)
• More use scenarios
• Con’s
• More complicated design
• Technical limitations
• Pro’s
• Simpler design
• Potentially lighter
• Con’s
• Dependent on water source
• Limit to power ability
• Requires more work from user
In the end, the battery design fulfills requirements in a more efficient manner
Updated Customer Requirements
Updated Engineering Requirements
Updated Engineering Matrix
System Functional Decomposition
Initial Single Pillar Design
Single Pillar Design
Scissor Lift Design
Full Battery Design for Both Cases
1 Raise Device Water Power Battery Power Inflation Power Remote ControlMagnetic
RepulsionChair Crane
2 Transfer Device
Getting items for
support (trapeze
handle)
Use of crutchesAutomation to lift
user to the device
Personal
assistant to help
user to device
Incorporate
user's assist
device
3 Assist Legs
Personal
Assistant to help
legs be secured
Water power
Battery power
(platform slides
out)
Remote controlReclining
Platform
4Rotate/Slide
DeviceManually Water power Battery power
Personal
assistantSpring loaded Remote Control
5 Lower Device Water Power Battery PowerInflation Under
chairRemote Control
Magnetic
RepulsionChair Crane
6Turn on Water to
fill tub
Manually turn
knob
Personal
AssistantRemote Control Relocate knobs
5 61 2 3 4Sub function
Solutions
Concept Selection
Criteria
Scissor Design Pillar Design
1 Raise Device + -
2 Transfer Device S S
3 Assist Legs S S
4 Rotate/Slide Device S S
5 Lower Device + -
6 Turn on Water to Fill Tub S S
7 Affordable - +
8 Fits Time Constraints + -
9 Safety + -
10 Light Weight - +
11 Portable + -
12 Durability + -
+ 6 2
- 2 6
Pro’s & Con’s of the Lift Designs
Pillar Lift
• Pro’s • Lightweight
• Simpler design
• Con’s • Some features may be
manually operated
• Weaker mechanically
• More prone to tipping
• Lift motor/mechanisms weaker
• Limited mobility and range of motion
Scissor Lift
• Pro’s • Stronger mechanics
• Able to lift more
• More automation possible
• More Stable
• Con’s • Larger -> heavier
• More costly
• Greater risk of electrical injury
Ultimately, the scissor lift is able to better satisfy project needs
Pillar Lift CAD Design
Bathroom
Electrical Architecture
AC/DC Converter Battery 12/24 V Acutator Moving Parts
Controller
220V60 A
Mechanical Architecture
Power Calculations
Extending Arm Calculations
• Stress
• 10.46 ksi
• Deflection
• 0.0937 in
Scissor Lift Calculations
• Stress
• 3.92 ksi
• Deflection
• 0.0031 in
Pillar Lift Calculations
• Stress
• 1.49 ksi
• Deflection
• 0.4675 in
Stress Analysis for Scissor Lift
Figure (1) – Von Mises Stress Note: ksi value was limited to 6 ksi to show stress colors in support area. Max stress value marked was 4.8 ksi.
Scissor Lift Displacement
Figure (2) - Displacement Note: Figure 2 shows the maximum displacement in inches of the support frame. Max value marked was 0.03262 in.
Scissor Lift Modified Disp.
Figure (3) – Displacement Limit Figure 3 shows a limit on displacement to farther show the dispersion of displacement on the scissor frame. Max value was 0.007 in.
Stress Analysis for Extending Arm
Figure (4) – Von Mises Stress Analysis It is noted that the stress range in the vertical pillar area ranges from 2-10.5 ksi. The acceptable stress value for stainless steel is 30-36 ksi.
Extending Arm Displacement
Figure (5) – Displacement As suspected, the largest displacement values are shown at the edge of the horizontal pillar. The value was measured to be 0.1254 in.
Extending Arm F.O.S.
Figure (6) – Factor of Safety In the medical field, most companies try to aim for a F.O.S. range of 2-4. From that assumption, we will follow that guideline when it comes to the stress analysis of our frame for the bathtub lift. The noted F.O.S. range on the vertical pillar was from 3-7.
Ergonomics Important factors to consider: • Intended users can fit
the device • Lumbar support • Arm rest height and
length • Leg clearance
** All measurements are based on ANSUR Database
Bill of Materials Material Name Weight (per cc^3) Elastic Modulus(ksi) Tensile Strength (Psi) Shear Strength (psi) Corrosive?
1 Fiberglass 2.49 20500 No
2 Gel coated Fiber Glass 2.49 20500 No
3 Acryllic 1.2 5420-10700 No
4
5
Material Name Weight (per cc^3) Elastic Modulus(ksi) Tensile Strength (Psi) Shear Strength (psi) Corrosive?
1 Carbon fiber 1.6 15954 No
2 Aluminum 2.69 40000 No
3
4
5
Material Name Weight (per cc^3) Elastic Modulus(ksi) Tensile Strength (Psi) Shear Strength (psi) Corrosive?
1 Fiberglass 2.49 20500 No
2 Carbon Fiber 1.6 15954 No
3 4140 Carbon Alloy Steel (Annealed) 7.85 60200 No
4 Polyurethane Alloy 0.970-1.40 1740-9720 4930-7690
5
Material Name Weight (per cc^3) Elastic Modulus(ksi) Tensile Strength (Psi) Shear Strength (psi) Corrosive?
1 A36 Steel 7.85 36300 Yes
2 4140 Carbon Alloy Steel (Annealed) 7.85 60200 No
3 Stainless Steel 0.19-9.01 11200-46000 6150-348000 No
4
5
Material Name Weight (per cc^3) Elastic Modulus(ksi) Tensile Strength (Psi) Shear Strength (psi) Corrosive?
1 Gel Coated Fiber Glass 2.49 20500 No
2
3
4
5
Material Name Weight (per cc^3) Elastic Modulus(ksi) Tensile Strength (Psi) Shear Strength (psi) Corrosive?
1 A36 Steel 7.85 36300 Yes
2 4140 Carbon Alloy Steel (Annealed) 7.85 60200 No
3 Stainless Steel 0.19-9.01 11200-46000 6150-348000 No
4
5
Extendable Arm
Chair (Seating Material)
Chair (Frame)
Base (excluding steel fixture for extendable pillar and sunction cups)
Extendable Pillar (Raises/Lowers Chair)
Arm Rest
Bill of Materials
Material Cost
Stainless Steel (Beam) 60.00$
Stainless Steel (Outside Channel) 100.00$
Battery with Charger 250.00$
Stainless Steel (for legs/lift) 51.00$
Suction Cups (4x) 100.00$
Aluminum Pipe 80.00$
Gel Coated Fiber Glass
Gel Coat 70.00$
Fiber Glass 26.00$
Mold 200.00$
Control Module & Electrical Wiring 250.00$
Actuator 350.00$
Total 1,537.00$
Total with 30% increase 1,998.10$
Power Sources – Electrical Actuator vs. Servo Motor • Upon review, the electric actuator would be a perfect fit in
assisting with the raising and lowering of the chair frame.
• Several companies were contacted for more advanced specs of the actuators and the main issue was that they are not waterproof.
• Therefore 2 scenarios rise up, the first is to do further research on alternative methods and the second is to design a waterproof housing for the actuator (that would take up a significant amount of time).
Risk Assessment Risk Item Cause Effect Likelihood Severity Importance Actions to Minimize Owner
1User injury due to
falling/slipping off device
No adding arm rails.
Combination of
material, water and
human skin not
having enough
friction causing user
to slip.
Minor to severe injury to the
customer/user1 3 3
Implement a safety
device and use high
friction materials
Team
2 ElectrocutionExposed electrical
components
User may be electrocuted by
direct contact with device or
through water
1 3 3
Design electrical
components to be
isolated/sealed
from rest of device
Team
3Electric power supply
inconsistent
Charge from battery
may not be
sufficient to operate
device when running
low
User may experience longer
operation times or may
become trapped in tub
2 3 6
Apply a warning
system/visual
indicator that the
battery is low.
Team
4 Device weight capacity
Device not able to
lift well over the
minimum
requirement
Device fails under heavy
loading, trapping and possibly
injuring user
1 3 3
Through testing
device must lift
>150 lbs
Team
5
Not being able to fulfill
requirements of broad user
base (height/weight
differences)
Not conducting an
ergonomics study on
the stature of the
users percentile and
their reach
User may be too big or too
small for device. User may get
injured due to lack of space or
not being able to reach certain
items. Customer dissatisfaction
2 2 4
Conducting
ergonomic
experiments on the
target percentile
range
Amos
6 Fixture dimensions
Measurement errors
of the bath tub and
the device. Not
considering
thickness of
materials in specs.
Device not able to fit in the
tub. Customer not being able
to use the device.
2 3 6
Have multiple team
members measure
the dimension of
the tub and for
every step of the
process, re-measure
to verify meeting
constraints
Team
7 Safety of user’s legs
When fixture is
lowering it does not
allow enough room
for legs
Minor to sever injury to the
customer/users legs 1 3 3
Apply a foot rest at
the base of the
device so the user
can place their feet
before operating
Team
8Transfer from starting position
to the device
Unsafe transition
from starting
position to the
device
Possible falling injury 1 3 3
Option1: Having the
device being able to
slide out the tub for
the user to access.
Option 2: Ensure
that the device can
rotate out of the
tub and is stable for
users that can stand
to use as a support.
Team
9Not being able to meet
deadlines/milestones
Not having a well
developed project
plan and keeping it
updated
Product delay which may lost
customers trust 2 2 4
Have daily or
weekly updates on
assignments and if
help is needed Team
10 Going over budget
Not keeping track of
budget or knowing
what the budget is
Having to ask for more or
falling short on supplies to
develop the product.
1 1 1Schedule to audit
budget every 2
weeks. Team
11All team members not being
able to meet
Miscommunication
or lack of
communication
between team
members
Team members missing
meetings or not being active in
their roles
2 1 2
Communicate with
team verbal and
text/email when
and where will
meetings will take
place. Amos
12User hand getting injured in
the process of using the seat
Exposed folding
mechanism and/or
seat lowering to
quickly
Hand chopped off 2 3 3
Ensure through the
proof of concept
the device will not
lower quickly or
collapse. In
addition, make a
safe folding
mechanism. Team
Risk Assessment
Risk Item Cause Effect Likelihood Severity Importance Actions to Minimize Owner
1User injury due to
falling/slipping off device
No adding arm rails.
Combination of
material, water and
human skin not
having enough
friction causing user
to slip.
Minor to severe injury to the
customer/user1 3 3
Implement a safety
device and use high
friction materials
Team
2 ElectrocutionExposed electrical
components
User may be electrocuted by
direct contact with device or
through water
1 3 3
Design electrical
components to be
isolated/sealed
from rest of device
Team
3Electric power supply
inconsistent
Charge from battery
may not be
sufficient to operate
device when running
low
User may experience longer
operation times or may
become trapped in tub
2 3 6
Apply a warning
system/visual
indicator that the
battery is low.
Team
4 Device weight capacity
Device not able to
lift well over the
minimum
requirement
Device fails under heavy
loading, trapping and possibly
injuring user
1 3 3
Through testing
device must lift
>150 lbs
Team
5
Not being able to fulfill
requirements of broad user
base (height/weight
differences)
Not conducting an
ergonomics study on
the stature of the
users percentile and
their reach
User may be too big or too
small for device. User may get
injured due to lack of space or
not being able to reach certain
items. Customer dissatisfaction
2 2 4
Conducting
ergonomic
experiments on the
target percentile
range
Amos
6 Fixture dimensions
Measurement errors
of the bath tub and
the device. Not
considering
thickness of
materials in specs.
Device not able to fit in the
tub. Customer not being able
to use the device.
2 3 6
Have multiple team
members measure
the dimension of
the tub and for
every step of the
process, re-measure
to verify meeting
constraints
Team
7 Safety of user’s legs
When fixture is
lowering it does not
allow enough room
for legs
Minor to sever injury to the
customer/users legs 1 3 3
Apply a foot rest at
the base of the
device so the user
can place their feet
before operating
Team
8Transfer from starting position
to the device
Unsafe transition
from starting
position to the
device
Possible falling injury 1 3 3
Option1: Having the
device being able to
slide out the tub for
the user to access.
Option 2: Ensure
that the device can
rotate out of the
tub and is stable for
users that can stand
to use as a support.
Team
9Not being able to meet
deadlines/milestones
Not having a well
developed project
plan and keeping it
updated
Product delay which may lost
customers trust 2 2 4
Have daily or
weekly updates on
assignments and if
help is needed Team
10 Going over budget
Not keeping track of
budget or knowing
what the budget is
Having to ask for more or
falling short on supplies to
develop the product.
1 1 1Schedule to audit
budget every 2
weeks. Team
11All team members not being
able to meet
Miscommunication
or lack of
communication
between team
members
Team members missing
meetings or not being active in
their roles
2 1 2
Communicate with
team verbal and
text/email when
and where will
meetings will take
place. Amos
12User hand getting injured in
the process of using the seat
Exposed folding
mechanism and/or
seat lowering to
quickly
Hand chopped off 2 3 3
Ensure through the
proof of concept
the device will not
lower quickly or
collapse. In
addition, make a
safe folding
mechanism. Team
Risk Assessment
Risk Item Cause Effect Likelihood Severity Importance Actions to Minimize Owner
1User injury due to
falling/slipping off device
No adding arm rails.
Combination of
material, water and
human skin not
having enough
friction causing user
to slip.
Minor to severe injury to the
customer/user1 3 3
Implement a safety
device and use high
friction materials
Team
2 ElectrocutionExposed electrical
components
User may be electrocuted by
direct contact with device or
through water
1 3 3
Design electrical
components to be
isolated/sealed
from rest of device
Team
3Electric power supply
inconsistent
Charge from battery
may not be
sufficient to operate
device when running
low
User may experience longer
operation times or may
become trapped in tub
2 3 6
Apply a warning
system/visual
indicator that the
battery is low.
Team
4 Device weight capacity
Device not able to
lift well over the
minimum
requirement
Device fails under heavy
loading, trapping and possibly
injuring user
1 3 3
Through testing
device must lift
>150 lbs
Team
5
Not being able to fulfill
requirements of broad user
base (height/weight
differences)
Not conducting an
ergonomics study on
the stature of the
users percentile and
their reach
User may be too big or too
small for device. User may get
injured due to lack of space or
not being able to reach certain
items. Customer dissatisfaction
2 2 4
Conducting
ergonomic
experiments on the
target percentile
range
Amos
6 Fixture dimensions
Measurement errors
of the bath tub and
the device. Not
considering
thickness of
materials in specs.
Device not able to fit in the
tub. Customer not being able
to use the device.
2 3 6
Have multiple team
members measure
the dimension of
the tub and for
every step of the
process, re-measure
to verify meeting
constraints
Team
7 Safety of user’s legs
When fixture is
lowering it does not
allow enough room
for legs
Minor to sever injury to the
customer/users legs 1 3 3
Apply a foot rest at
the base of the
device so the user
can place their feet
before operating
Team
8Transfer from starting position
to the device
Unsafe transition
from starting
position to the
device
Possible falling injury 1 3 3
Option1: Having the
device being able to
slide out the tub for
the user to access.
Option 2: Ensure
that the device can
rotate out of the
tub and is stable for
users that can stand
to use as a support.
Team
9Not being able to meet
deadlines/milestones
Not having a well
developed project
plan and keeping it
updated
Product delay which may lost
customers trust 2 2 4
Have daily or
weekly updates on
assignments and if
help is needed Team
10 Going over budget
Not keeping track of
budget or knowing
what the budget is
Having to ask for more or
falling short on supplies to
develop the product.
1 1 1Schedule to audit
budget every 2
weeks. Team
11All team members not being
able to meet
Miscommunication
or lack of
communication
between team
members
Team members missing
meetings or not being active in
their roles
2 1 2
Communicate with
team verbal and
text/email when
and where will
meetings will take
place. Amos
12User hand getting injured in
the process of using the seat
Exposed folding
mechanism and/or
seat lowering to
quickly
Hand chopped off 2 3 3
Ensure through the
proof of concept
the device will not
lower quickly or
collapse. In
addition, make a
safe folding
mechanism. Team
6
Test Plan
• Team plans on purchasing a small actuator and rechargeable power source
• Actuator ~ $20-30
• Battery ~ $10
• Create a scaled test rig to test design feasibility
• Conduct worst-case scenario simulations
Team’s Vision
Project Plan for WK 10-12 ID Action Items Owner
1
Incorporate Ergonomics drawings with CAD
designs Amos, Jeremy, & Andrew
2Refine CAD designs
Andrew
3Design of control module
Andrew & Jeremy
4Develop a battery charging system
Jeremy & Richard
5Contact and meet with Theresa
Team
6Establish proof of concept in all critical areas
Team
7Develop a test plan for the device
Richard
8Refine Bill of Materials
Richard & Amos
9
Arrange meetings with faculty to review Detailed
Design for all critical areas Team
10Purchase actuator
Team
Project Plan for WK 10-12
Questions?