P16006: Tub Lift 2

Problem Definition

Table of Contents

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Problem Definition Documents

Team Vision for Problem Definition Phase

During this phase, our team met with our customer and determined the customer requirements. From those requirements, we established engineering metrics that were necessary to ensure the customer requirements were met. Once the relations between the customer and engineering requirements were understood, our team began brainstorming designs that would fulfill the customer and engineering needs.

After accomplishing the above goals and we additionally assigned some more specific team roles within our group. A preliminary schedule to help plan our team's project over the duration of MSD was generated along with some risks that we would need to considered during the design process. A CAD drawing of the customer's bathroom was created during the establishment of the customer requirements to help visualize constraints when we begin the next phase of the design process. Although we have some risks established and a general project plan, these two aspects will need refinement and expansion as the project progresses. In the same way our design will be iterated, assessment of risks and the development of the project schedule will need to be iterated in order to account for setbacks and all new information encountered during the design process.

Project Summary

Theresa Loce, a wheelchair user relies on a hydraulic power bath lift to assist her with entering and exiting her bath tub. Theresa has suffered from polio in the past and is gradually losing movement in her extremities as a result. The water-powered lift that she currently utilizes has been requiring frequent repairs due to its age (parts are becoming scarce, expensive and possibly unreliable). Development of a new, affordable and easy-to-use lift mechanism for her bath tub is desired. The final mechanism must be able to both lower, lift and rotate Theresa into and out of her tub in a timely manner, while taking into consideration the strict spatial constraints of her bathroom. An ergonomic and safe design is preferred.

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1 Page Project Summary

Interview Questions

Use Cases



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Scenario Of Use

Project Goals and Key Deliverables

By the end of the project the customer should expect to receive a replacement tub lift that is capable of swiveling 90 degrees and can lower her into the tub and raise her out of the tub. The final product should have no issues with the integrity of the structure or sturdiness of the design when placed inside the customer's tub. The end product should also be ergonomically sound and meet the comfort requirement established in the customer requirement.

Customer Requirements (Needs)


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Tub Lift rev 2 Customer and Engineering Requirements

Engineering Requirements (Metrics & Specifications)


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Tub Lift rev 2 Customer and Engineering Requirements


The success of the tub lift project will be determined by the ability to address a few critical constraints to the project. The first and most obvious constraint is that the customer's bathroom is very constrained for space. As a result, we have taken measurements of the bathroom and have produced a CAD layout of the area. We will have to be mindful of the range of motion of the lift, which would make certain, more bulky or permanent designs infeasible. Additionally, we have to consider that the customer is an elderly lady with limited use of her legs and diminishing strength in her upper extremities. It will be critical to produce a design that can be easily utilized by such a person. The design also should be highly ergonomic to provide additional accommodations.


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Bathroom CAD Layout

House of Quality


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Tub Lift rev 2 House of Quality

Design Review Materials

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Problem Definition Design Review

Plans for next phase

As a team, we would like to focus on developing both a method for swiveling the chair on the tub lift as well as a method of lifting and lowering the chair. We plan to develop several designs to accomplish both. Once done, we will determine which theoretical methods are best and evaluate which materials should be used to create the lift (ex. which type of metals). After the materials are determined, we will seek to analyze the design using mechanics and then create a Bill of Materials. The Bill of Materials will be based off the feasibility analysis along with the relations developed in the House of Quality between Customer Requirements and Engineering Requirements in order to justify the necessity of each material utilized in specific subsystems.


Schedule network derived from project plan created on Microsoft Project.

Please refer to the following attachments to view individual plans for the next phase of the project:

Branch - System Design Plan
Hall - System Design Plan
Krall - System Design Plan
Swearingen - System Design Plan

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