P14006Bath Tub Lift

Phase IV ReviewAmos BaptisteJeremy CzeczulinAndrew HughesRichard Prilenski

IntroductionsName Major/Role

Amos Baptiste Industrial & Systems Engineer/Team Leader

Jeremy Czeczulin Mechanical Engineer

Andrew Hughes Mechanical Engineer

Richard Prilenski Mechanical Engineer

Agenda• Phase III Overview

• Problem Definition• Action Items

• Refined Drawings• Stress Analysis• Materials• Prototype• Team Assessment• Schedule• Customer/Engineering Requirement• Risk 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: eademe@rit.edu

• Faculty Guide: Art North• Contact: ajnddm@rit.edu

• Sponsor (financial support): RIT & Theresa Loce

Issues to Address from Phase III• Fiber glass needs to be looked more into as It may not be water resistant and itchy• Need to calculate bending stress• Put a guard to prevent hand or body part to be between scissor lift• Look at backup plan if suction cups fail & how to reinforce the suction cup base• Control module• Make a design• Buttons• Possible mock to see how it feels

• Where will the actuator be positioned?• How to eliminate the risk of the user being shocked?• Consider twisting a central axis• Try two parallel roller/tracks for stability• Electrical safety requirements• Battery design and wiring• Bottom of bath tubs are textured look in to for suction cups• When the actuator is at the top will it lock in place or slowly go back down?• Steel and Aluminum together in water may cause corrosion. Be more specific on grade of material• Need bearings and pins for detailed designs of the model• Plan for where and corrosion issues with reflective motion parts

Action Items from Phase IIIAction Item Owner Issue(s) to AddressCreate physical prototype of the bath tub lift .

Richard & Jeremy • Trying two parallel rollers for stability

• Proof of design concept• Determine position for actuator

Create a design and prototype for controller

Amos • Control module design• Possible mock of how it feels

Refine CAD design Andrew • Ensure the chair fits the target percentile

• Determine location of bearing and pins

• Put a guard to prevent risk of hand injury when lowering device.

Conduct stress analysis Richard • Stress from bending

Refine BOM Amos • Fiber glass on seat may not be waterproof and itchy to user

• Steel and Aluminum together in water may cause corrosion.

• Specify grades

Contact Linak & research actuator Richard & Jeremy • Address the risk of shocking the user

• Electrical safety requirements

Refined CAD Model

Continued

Continued

Stress Analysis (Initial Position)

Stress Analysis

Figure 1: Maximum stress noted is 42.18 ksi in the pin region. However it is “micro stress”.

Stress - Modified Analysis

Figure 2: Pin stress exceeds 36 ksi. Stress values of the scissor region ranges from 5-20 ksi.

Displacement Analysis

Figure 3: Maximum displacement noted was 0.03537 in. While scissor region obtained 0.007 – 0.023 in.

F.O.S. Analysis

Figure 4: *Note: For medical devices the FOS range is usually 2-4.

Stress Analysis(Maximum Extended Position)

Stress Analysis

Figure 5: Max stress occurred in the upper pin region. After observing this analysis of Figure 1 and Figure 5, it is evident that a high grade of steel must be used for the pins.

Stress Analysis - Modified

Figure 6: Stress values in the scissor region were around 3-22 ksi.

Displacement Analysis

Figure 7: Max displacement at the edge of the extending pillar was 0.1456 in.

Displacement Analysis - Modified

Figure 8: Better shows the displacement dispersion.

Factor of Safety

Figure 9: FOS range in the scissor region was around 1.5 to 6 ( Increasing the thickness of the scissor frame by 1/8” will increase the lower FOS values to the desired range). The FOS values for the pins dropped below 1 due to the lower grade of steel used for this analysis and thus farther confirms a high grade of carbon steel must be used for the pin region.

Materials AddedMaterial Component Properties

Polyamide • Chair seat• Back rest• Control module

• Hard and brittle• Resistant to abrasion,

shrinkage and heat• Water resistant

Medium Carbon Steel • Scissor Lift• Beam• Outside Channel

• Ductile• High strength• Good Wear resistance

Rubber coating • Scissor Lift• Beam• Outside Channel

• Can be applied to steel

• Will help make steel water resistant

Bill of MaterialsMaterial Name Weight (per cc^3) Elastic Modulus(ksi) Tensile Strength (Psi) Shear Strength (psi) Corrosive?

1 Fiberglass 2.49 20500 No2 Gel coated Fiber Glass 2.49 20500 No3 Acryllic 1.2 5420-10700 No4 Polyamides5

Material Name Weight (per cc^3) Elastic Modulus(ksi) Tensile Strength (Psi) Shear Strength (psi) Corrosive?1 Carbon fiber 1.6 15954 No2 Aluminum 2.69 40000 No345

Material Name Weight (per cc^3) Elastic Modulus(ksi) Tensile Strength (Psi) Shear Strength (psi) Corrosive?1 Fiberglass 2.49 20500 No2 Carbon Fiber 1.6 15954 No3 4140 Carbon Alloy Steel (Annealed) 7.85 60200 No4 Polyurethane Alloy 0.970-1.40 1740-9720 4930-76905

Material Name Weight (per cc^3) Elastic Modulus(ksi) Tensile Strength (Psi) Shear Strength (psi) Corrosive?1 A36 Steel 7.85 36300 Yes2 4140 Carbon Alloy Steel (Annealed) 7.85 60200 No3 Stainless Steel 0.19-9.01 11200-46000 6150-348000 No4 Medium Carbon Steel 7.75 65300-396000 No5

Material Name Weight (per cc^3) Elastic Modulus(ksi) Tensile Strength (Psi) Shear Strength (psi) Corrosive?1 Gel Coated Fiber Glass 2.49 20500 No2 Polyamides345

Material Name Weight (per cc^3) Elastic Modulus(ksi) Tensile Strength (Psi) Shear Strength (psi) Corrosive?1 A36 Steel 7.85 36300 Yes2 4140 Carbon Alloy Steel (Annealed) 7.85 60200 No3 Stainless Steel 0.19-9.01 11200-46000 6150-348000 No4 Medium Carbon Steel 7.75 65300-396000 No5

Extendable Arm

Chair (Seating Material)

Chair (Frame)

Base (excluding steel fixture for extendable pillar and sunction cups)

Extendable Pillar (Raises/Lowers Chair)

Arm Rest

LA31 Careline Linear Actuator• Provided by Linak• 6,000N (1350lb) max push, 4,000N (900lb) pull• IPX6 protection class• Emergency lowering/retraction• 24V DC magnet motor, 2.25m cable• Max stroke length 250mm

HB70 Handset• Control from LINAK, compatible with LA31• IPX6 protection class• Easy to use interface• Hang-on clip• Operate up multiple actuators• 0.6m cord

IPX Ratings

Controller• Consist of:• Power button• Directional pads to

move the chair• Home button

Prototype

Built a prototype using:• PVC pipes• Rollers• Rope• Pulley• PVC Cement and Primer• Screws

All the materials were purchased at Home Depot on Jefferson Rd.

Prototype

Team AssessmentAction Item Owner StatusCreate physical prototype of the bath tub lift

Richard & Jeremy • In progress

Create a design and prototype for controller

Amos • In progress- currently waiting on 3D print of controller

Refine CAD design Andrew • In progress- Still making adjustment to design according to proof of concept

Conduct stress analysis Richard • CompletedRefine BOM Amos • Completed

Contact Linak Richard & Jeremy • In progress- Need to consider looking at other options for backup.

WK 13-15 PlanTask Name Owner (S)

Purchase actuator Jeremy & RichardDevelop PVC Prototype Jeremy & RichardRefine CAD designs AndrewEnsure device meet OSHA Electrical Safety Requirements Amos

Incorportate feedback from Phase 4 Review for Phase 5 Team

Develop manufacturing design AmosHave final meeting with Theresa before summer Team

Updated Customer Requirements

Updated Engineering Requirements

Updated Engineering Matrix

Risk AssessmentRisk 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/user

1 3 3Implement a safety device and use high friction materials

Team

2 Shocking the userExposed electrical components

User may be shocked 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 3Through 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

8 Team

9 2 2 4

Team

10 1 1 1

Team

11 2 1 2

Amos

12

Team

13 1 3 3

Team

Risk Assessment

Risk Item Cause Effect Likelihood Severity Importance Actions to Minimize Owner

1 1 3 3 Team

2

3 2 3 6 Team

4 1 3 3 Team

5 2 2 4 Amos

6 2 3 6 Team

7 1 3 3 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 budgetNot 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 6

Ensure through the proof of concept the device will not lower quickly or collapse. In addition, make a safe folding mechanism. Team

13 Device tipping over

Sunction cup failure or the device not properly secured to the base of the tub.

Minor to sever injury to the customer

1 3 3

Reinforce sunction cup base and have a back up plan in the case the sunction cups fail. Team