P14006: Bathtub Lift

Systems Design

Table of Contents

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Benchmarking Specs

Photos from bench marking can be found in the Phase 2 Review presentation in the bench-marking section. The specifications were collected from a catalog provided by Southside Medical Supplies in Rochester,NY.

Concept Development (generation, improvement, selection)

Morphological Analysis

Concept Selection - Scissor vs. Pillar

Functional Decomposition

Functional Decomposition

Systems Architecture

Mechanical Architecture

Electrical Architecture


Ergonomics Model


Power Requirements and Basic Calculations

Battery Power Requirements

Extending Arm Analysis

Scissor Lift Analysis

Pillar Lift Analysis

Stress and Displacement Simulations

Stress Analysis for Scissor Lift

Scissor Lift Displacement

Scissor Lift Modified Displacement

Stress Analysis for Extending Arm

Extending Arm Displacement

Extending Arm Factor of Safety

(For example, basic engineering analysis or simulation, mockups, benchmarking results)

Risk Assessment

ID Risk Item Cause Effect Likelihood Severity Importance Actions to minimize Owner
1 User 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 3 Implement a safety device and use high friction materials Team
2 Water power supply inconsistent Psi level jump due to drop in water pressure User may experience discomfort while operating device due to rough motions 1 1 1 Run a test to see if users water pressure is consistent Team
3 Electric 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 Have multiple team members measure the dimension of the tub and for every step of the process, re-measure to verify meeting constraints Team
6 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
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 Transfer from starting position to the device Unsafe transition from starting position to the device Possible falling injury 1 3 3 Option 1: 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
9 Not 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 1 Schedule to audit budget every 2 weeks. Team
11 All 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. Team

Problem Tracking

Problem Tracking

Systems Design Review

Phase 2 Review

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