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Our goal is to modify a Wheelchair to have a sunshade, a table, and to assist the child in sitting up. This will enable the child to participate in classroom and day-to-day activities.
Our assigned child suffers from gene mutation called KCNQ2, which causes seizures and some degree of developmental impairment involving one or more domains (motor, social, language, cognition). She currently receives physical, occupational, feeding/ speech, and developmental therapies on a weekly basis. The child can barely sit up unsupported and cannot stand or walk independently, all of which prevents her from participating in playtime, mealtimes, classroom activities, arts & crafts, and most day-to-day activities.
Her mother would like us to design and fabricate a modified wheelchair in order for her to participate in classroom activities, mealtimes, arts & crafts, playtime, etc. The wheelchair will need torse support, a removeable table-tray, a removeable sunshade, as well as toys and lights for the child to play with. The mother also emphasized the importance of the wheelchair and its attachments being as lightweight as possible, as well as all of the attachments being easily removeable.
The majority of background research was spent finding ways to design a suitable wheelchair that was as lightweight as possible without diminishing the overall quality of the wheelchair. We did some background research on the disease our child was diagnosed with, KCNQ2, and spent a lot of time making sure our supports would secure her tightly without being too uncomfortable and giving her room so that she would not fully depend on the support, since she is trying to increase her overall strength. We also spent a lot of time looking for base wheelchairs that would be suitable for the child and be easily modified for our attachments.
In this concept design we decided to implement a detachable sunshade with brackets on each side the of chair to hold the shade. We are going with “backpack style” straps for the child’s support, and a table tray that can be taken on and off very easily. There will also be a Bluetooth speaker attached for music, and toys/lights for the table. We want to include a mesh bag on the back to store accessories.
In this concept design we decided to implement a detachable umbrella sunshade that slides into a rigid casing that can rotate accordingly. We are going with “car seat style” straps for the child’s support, and a theater style table that can swivel back and forth when in use or not. There will also be a Bluetooth speaker attached for music, and toys/lights for the table. We want to include a mesh bag on the back to store accessories.
In this concept design we decided to implement an attached sunshade that is connected to a rigid bar to hold the shade. We are going with the single strap Velcro style for the child’s support, and a table that can be taken on/off from a pole support attached to the wheelchair. There will also be a Bluetooth speaker attached for music, and toys/lights for the table. We want to include a mesh bag on the back to store accessories.
We decided to go with concept design 1. This choice was largely due to the mother wanting this design rather than the other 2, but also design 1 came out the best in our decision matrix.
In our selected design, the wheel chair will have a detachable sunshade, a table made to attach to removable supports, backpack straps installed for torso support, a housing for a Bluetooth speaker, and toys integrated into one of the tables.
Sun Shade:
Rather than create an entire shade from the ground up, we decided to build a detachable base in which we could modify and permanently attach a pre-existing shade to. While shades for similar uses exist, no design seemed to have the detachability or precise fit we needed. The base would consist of a half ring of aluminum tubing with 2 steel pins fixed at both ends. These pins would slide into aluminum slots welded just in front of the chair’s handles.
Activity Table:
We decided to make use of the 3-D printers here on campus to develop the table for the wheelchair. It is 14.5in wide with a depth of 8in, purposely made to slide into the front-center of the chair and be close enough for the child to reach her arms out and carry out everyday activities. The table will be made from PLA plastic and will made to become detachable when necessary. It also will have a cup holder on the table for when the child has a beverage, and toys will be implemented on the surface of the table.
Table Supports:
The table supports are designed to slide over the sides of the wheel chair frame, in front of the arm rests. They will be secured using double sided button pins that will be installed in two locations on the wheelchair’s frame. This will make attaching and detaching them very easy. Each will have a slot for the activity table to slide into them and lock into place, while still allowing the table to be easily removed. The table supports, similar to the table, will be made of PLA plastic and 3-D printed.
The purpose of this Analysis was to apply two different forces in the hotspots of the table design. One where the cupholder will hold beverages and one where the table will hold meals, activities, etc. The stresses and strains on both hotspots were extremely low and the max displacement was nothing in scale to worry about given that we tested a 40psi load. This table should hold up to any everyday activity the child will be using it for.
The purpose of this analysis was to apply pressure across the top of the tables supports, where the table will be sitting, in order to measure any potential displacement. The maximum displacement was less than one tenth of a millimeter with an overestimated 40psi pressure. The table supports should hold up to any everyday activity the child will be using it for.
Intuitively, these slots that support the shade would be a critical point for failure due to any unexpected loads or forces acting on our shade. A Solidworks simulation of an excessive 50 lbf was ran on the portion of this model that will bear the weight of the shade. The analysis showed that, even here, the stresses generated would fall well below the yield strength of the selected material. Therefore, the current design should prove durable to most any unforeseen conditions.
The majority of our fabrication process was spent 3D printing, we had the printers fail/break on us several times. However, we eventually attained our final prints. We also painted the wheelchair, strengthened the table using aluminum tabs, attached backpack straps for torso support, 3D printed an attachment for opening the sunshade, and machined a guiding slot/tab for attaching the sunshade to the wheelchair.
For safe use, make sure to put safety straps over both shoulders and tighten them to an appropriate secureness. When attaching the play/eat table to the wheelchair make sure to slide in tabs to the front of the child’s body evenly. When detaching the table, lift it vertical before attempting to slide it off the supports. When applying weight to the tables, do not exceed 150lb. When attaching the bungees to the sunshade and table supports, use caution, as there can be slight tension in the bungee.
