Elevate
Mechanical seat lift retrofit for manual wheelchair users providing up to 20cm of added height
MECHANICAL SEAT LIFT RETROFIT FOR MANUAL WHEELCHAIRS
LEADERSHIP
USER RESEARCH
PROTOTYPING
CAD
DESIGN FOR MANUFACTURING
DESIGN FOR ASSEMBLY
Many wheelchair users face not only physical challenges in seeing and reaching high up objects, but also social challenges in speaking and connecting with others eye to eye.
Elevate is a mechanical seat lift retrofit that can attach to manual wheelchairs. It provides up to 20cm of assisted elevation to address the physical and social challenges that come with living at a seated height.
Extensive research was conducted via interviews with manual wheelchair users at the Spaulding Rehabilitation Hospital in Boston to better understand the challenges they face and inform key use cases.
USER RESEARCH
Extensive research was conducted via interviews with manual wheelchair users at the Spaulding Rehabilitation Hospital in Boston to better understand the challenges they face and inform key use cases.
Users described to us the many situations where they were physically limited by their seated height. Anything as simple as reaching for a high shelf to transferring themselves to a chair taller than their wheelchair. However, beyond the physical limitations, users expressed that it can take an immense emotional toll when socialising with others. Not being able to talk to people at standing eye level often feels like a social disadvantage.
PROTOTYPE I
During the mechanical design, I led a group of four members focused on researching lifting mechanisms to find a safe and feasible option. A scissor lift and gas spring combo was found to be optimal. The scissor lift provided stability and the gas spring provided the lifting and locking mechanisms similar those found in a desk chair.
Several models were built to prototype individual parts of the design. My unit of five members built a conceptual prototype to test the lifting mechanism.
We disassembled a desk chair and integrated the gas spring lifting mechanism into the frame of a manual wheelchair with a bike handle attached to trigger the lifting mechanism (seen left). We tested this model ourselves to check the feasibility of this lifting mechanism.
PROTOTYPE II
Next, a working prototype was built by the whole team to test the feasibility of attaching a scissor lift and handle bars to a wheelchair frame and the feasibility of lifting a person via this mechanism. I helped to design and manufacture the four clamps that attach the seat lift to the wheelchair.
I led several rounds of testing with manual wheelchair users to better understand the pros and cons of our design.
PROTOTYPE II
The final prototype our team created was manufactured from steel, aluminium, high density foam, and thermoformed plastic. The device is designed to be compact, stable, and easy to use. I mainly worked on manufacturing the scissor lift.
ELEVATE
PROTOTYPING ● DESIGN FOR MANUFACTURING ● CAD ● USER RESEARCH ● LEADERSHIP
More details on skills
A mechanical seat lift retrofit for manual wheelchairs
3 month project at MIT, Fall 2018, Cambridge, MA, USA
Team of 20 mechanical engineering students
2.009 Mechanical Engineering Capstone Project presentation linked here
CONTEXT
Many wheelchair users face not only physical challenges in seeing and reaching high up objects, but also social challenges in speaking and connecting with others eye to eye.
Elevate is a mechanical seat lift retrofit that can attach to manual wheelchairs. It provides up to 8” of assisted elevation to address the physical and social challenges that come with living at a seated height.
USER RESEARCH
Several team members and I conducted extensive interviews with manual wheelchair users at the Spaulding Rehabilitation Hospital to better understand the challenges they face and inform key use cases.
USE CASE ILLUSTRATIONS
Transferring to a higher seat
Talking at eye level
Reaching high up objects
Users described to us the many situations where they were physically limited by their seated height. Anything as simple as reaching for a high shelf to transferring themselves to a chair taller than their wheelchair. However, beyond the physical limitations, users expressed that it can take an immense emotional toll when socialising with others. Not being able to talk to people at standing eye level often feels like a social disadvantage.
MECHANICAL RESEARCH
During the mechanical design, I led a group of four members focused on researching lifting mechanisms to find a safe and feasible option. Here I have illustrated a few that we considered. A scissor lift and gas spring combo was found to be optimal. The scissor lift provided stability and the gas spring provided the lifting and locking mechanisms similar those found in a desk chair.
CONCEPTUAL PROTOTYPE
Several models were built to prototype various parts of the design . My unit of five team members were tasked with building a conceptual prototype for the lifting mechanism.
We disassembled a desk chair and integrated the gas spring lifting mechanism into the frame of a manual wheelchair with a bike handle attached to trigger the lifting mechanism. We tested this model ourselves to check the feasibility of this lifting mechanism.
Conceptual prototype of lifting mechanism
Conceptual prototype of trigger mechanism
WORKING PROTOTYPE
Next, a working prototype was built by the whole team to test the feasibility of attaching a scissor lift and handle bars to a wheelchair frame and the feasibility of lifting a person via this mechanism. I helped to design and manufacture the four clamps that attach the seat lift to the wheelchair.
I led several rounds of testing with manual wheelchair users to better understand the pros and cons of our design.
Working prototype during user testing
Working prototype of scissor lift
DESIGN FOR MANUFACTURING
I designed and 3D modelled the arm lever used to trigger the gas spring elevation so that it can be mass manufactured through injection moulding with a hard, wear resistant thermoplastic.
The base of the lever required a complex parting line to keep the through holes at varying heights parallel to the parting plane.
I designed the mould plates with two removable core pins and a 1.5˚ draft to accommodate a textured material finish.
Here I created some CAD renderings and illustrations to show options for the seat assembly. At scale, the seat back and and seat frame can be manufactured through vacuum forming or carbon fibre layups to provide a strong and lightweight structure. Customisable forms are critical to keep in mind as these structures need to be optimized to the user’s body for daily comfort and to prevent pressure sores.
ALPHA PROTOTYPE
The final prototype our team created was manufactured from steel, aluminium, high density foam, and thermoformed plastic. The device is designed to be compact, stable, and easy to use. I mainly worked on manufacturing the scissor lift.
LIGHTWEIGHT
Manufacturing at scale would use titanium and carbon fibre composites weighing < 5 lbs, comparable to a text book.
COMPACT
The gas spring is placed behind the backrest, keeping it above the wheelchair axle and preventing it from catching on rough terrain.
STABLE
Testing and tipping calculations ensure that the user is still safe going up standardised accessibility ramps inclined at 5 ̊.
EASY TO USE
A purely mechanical system with no motors or batteries. The lifting mechanism is smooth, easy to use and changes height quickly.
Alpha prototype attached to manual wheelchair
Alpha prototype scissor lift mechanism
Alpha prototype attached to scissor lift mechanism
USER EXPERIENCE
Elevate transforms the user’s experience by elongating their reach, extending their line of sight, and bridging the gap when speaking eye to eye with others.
Seat lift locks at any height up to 20 cm
User can attach their choice of cushion to the rigid seat and back rest
Seat angle, or seat dump, is customisable for the user's comfort
User squeezes the lever and pushes off the armrests to raise the seat
A gas spring provides a lifting of 30 - 50% of the user’s weight to help as they push their body up
Four clamps secure the retrofit in place attaching to bars common to rigid lightweight wheelchair models most popular among target users
FINAL PRESENTATION
The alpha prototype was presented to an audience of approximately 40,000 people. As one of the three presenters, it was a thrilling experience to share this project with such a large audience.
