Designers: Shwetadwip Chowdhury, Shekar Eswarakrishnan, Wei Han, Xiao Li
Client Coordinators: Pam Duncan
Supervising Professors: Kevin Caves and Richard Goldberg
INTRODUCTION
Rhonda is an avid gardener and enjoys working outside, tending her garden and lawn. Several years ago, Rhonda sustained a spinal cord injury and as a result, she now relies on a manual wheelchair for her mobility. She cannot push a lawn mower and push her wheelchair at the same time and has to ask for help or pay someone to maintain her lawn. She has good upper body strength and can propel her chair throughout her yard, and she is highly motivated to be independent again with lawn care.
The purpose of this project is to enable our client to mow her lawn independently, efficiently, and safely, while sitting in her wheelchair. To accomplish this task, we modified string line trimmer and the operation is similar to using an upright vacuum cleaner, pushing and pulling with one arm. We added a mount to the client’s wheelchair so that she can easily transport the mower to and from her shed. The overall design is effective in allowing our client to mow her lawn independently and efficiently.
SUMMARY OF IMPACT
This device gives our client the ability to mow her grass, which she has not been able to do since her spinal cord injury. It also enables her to do something that she has always loved and enjoyed. Our client said: “I am so excited about this mower. When I was walking, I used to love mowing my grass. Now I can do it again. My yard is my haven – this will be perfect!”
TECHNICAL DESCRIPTION
The design consists of three major components: a string line trimmer; wheels to provide support and mobility; and a mounting device to secure the trimmer on the wheelchair.
A commercially available trimmer (Worx GT String Trimmer/Edger) was chosen because of its high capacity, lightweight lithium battery and its adjustability. The trimmer has an extendable shaft and a rotating joint that allows adjustment of the angle of the handle relative to the cutting head. A locking mechanism was removed from the joint to allow free motion of the handle (e.g. like an upright vacuum cleaner) to ensure the string remains level while cutting.
Support and mobility is achieved by attaching wheels to the string trimmer. The weight is supported by the two large wheels on either side of the cutting head. In addition, we attached pair of small wheels directly behind trimmer to provide additional points of contact with the ground so that the cutting head remains level. The side wheels were adapted from a pull cart for golf bags, and they were attached to the trimmer by fabricating a custom connector from HDPE plastic; the rear wheels were attached to the trimmer’s edging guard.
A mower mount was connected to the front of the client’s wheelchair to hold the mower while Rhonda wheels to different locations in her yard, or to and from her storage shed. This “gun rack” mount was created using PVC tubing, which connects to the wheelchair using a custom mounting bracket developed for a previous project.
The cost to develop the device was $296, including the cost of the Worx string trimmer.