Yiwen Wu
Engineer · Designer · Baker · Traveler
Automated Wheelchair Accessory
September 2013 - December 2013
Four Team Members
This was a class project with given design specifications and resources. This wheelchair accessory helps the disabled store a backpack (up to 12 lb) on the back of their wheelchair and move it to the side of the wheelchair in 9 second with a single switch. This would allow the user to easily access their backpack without any assistance. Thus, making the life and day-to-day tasks of a wheelchair confined student much easier. The mechanism stops when users accidentally put their hands at pinch points and decelerates at the last 30 degree of travel for safety.
Inspiration
Created a Pugh Chart of the given design requirements and other important criteria identified by the team.
Assigned weighing factor from 5, most important, to 1, least important, to each criterion.
Created a functional decomposition model to breakdown the design challenge into detailed steps of its energy distribution, analyze design external effects, and organize step functions.
Wheelchair worked on
Photo and drawing provided by University of Michigan ME 350 instructors.
Design criteria and corresponding weights
Functional decomposition
Ideation
Brainstormed potential mechanisms and design concepts to achieve design requirements.
Created sketches to illustrate design ideas and performed preliminary calculations.
Evaluated all concepts and adopted a four-bar linkage mechanism for final design based on the Pugh Chart created.
Designed a transmission to meet the calculated design speed-torque requirements.
Coded the motor, encoder, proximity sensors, and limit switches with Arduino to meet the time and safety requirements
Constructed a detailed 3D CAD model of the wheelchair accessory design.
Performed dynamic simulations and finite element analysis for design refinement.
Four-bar linkage mechanism design and analysis
Preliminary deflection calculation
Transmission design and analysis
Detailed CAD model of the wheelchair accessory design
Initial and final state of the wheelchair mechanism design
Dynamic simulation and analysis of the design
Wiring diagram
Implementation
Created a Bill of Materials for minimum cost and maximum manufacturability on campus.
Obtained materials from project kit, school machine shop tool crib, and online stores.
Manufactured all parts of the design through diverse processes including milling, lathing, drilling, cutting, and waterjetting.
Assembled the design and mounted the assembly onto the wheelchair
Conducted functionality tests and evaluated the wheelchair accessory performace against all design requirements.
Refined the design based on test results.
Bill of Materials
Drawing and manufacturing plan example
Assembled wheelchair accessory
