Project 9: Wheel Chair Adaptation

Abstract

The family is in need of some kind of wheel chair that is motorized for Avonlea to get around in. They are open to possible adaptation of the current activity chair that they have. We are taking team 7’s chair from the previous semester and making it functional.

Zander Delk, Nathan Keel, Jaxon Godsey, Daniel Rickert, Bryson Dobbs, Ethan Holcomb

Problem Statement

Taking the existing chair from the previous semester and making the chair function for the family in need. While doing this we will upgrade the chair to a subsequent iteration, fixing any issues that present themselves.

Design Specifications

Motorized
Lightweight
Able to ride over rough terrain, like gravel driveway
Motorized adjustable height
Adjustable head support with side supports
Foldable arm rests
Lap restraint, possible chest restraint
Adjustable footrest
Designed to grow with the child
Improve adjustability
Quality of life improvements

Background Research

Our background research involved us researching the previous teams unfinished product and Avonlea’s needs from the product. This required us to reach out to both the parents of Avonlea and the previous team to understand our scope of work.

Concept Design 1

Re-order the same motor control kit and swap them out to make the chair functional. This would require no modification to the current chair but has high cost and risks.

Concept Design 2

Order a different kit and modify the chair for fitment. This requires quite a bit of modification, time for shipping and high costs.

Concept Design 3

Salvage what works from the current chair and make the current system work. This requires little modification and high skill but little wait time and significantly less cost.

Selected Concept Design

Concept design 3 was chosen for financial reasons and expedited procurement.

Decision Matrix

Engineering Analysis 1

One of the things that our group noticed was that we needed an effective way to hide the motor controllers and other electrical components. The way we did this was by making a box that we could mount on the side of the chair. We built a box that could fit a 7.5″ by 10.5″ plate inside of it. We chose to mount the electrical components to the plate first, then slide the plate into the box. The box has two rectangular cut-outs to allow the motor controllers to get air. The six holes in the side will be used for easy wire connections to connect the motor wires to the components inside the box. The box will be capped with a lid that will latch to the sides of the box in order to allow easy access.

Engineering Analysis 2

For the new chair, we had to alter the footrest in order for it to appropriately fit Avolena. One of the requests was for the Avolena to be able to help around the kitchen making food. Therefore, we made sure when building the footrest to make sure that Avolena would be able to stand on the footrest if needed. We did this by adding a safety factor and rating the footrest for 50 pounds. Avolena is 33 pounds which would give her some room to be able to apply more weight on the footrest in order to help out in the kitchen.

Document Fabrication Process

Fabrication was only necessary for the new chair. We needed a system to increase the adjustability of the back rest. This was accomplished by making an “L” bracket out of pipe for the new back rest to mount to. These “L” brackets being made from pipe allows us to flip them up or down for increased height adjustment. Our next area of adjustment we needed was moving the backrest towards the front of the chair. This was accomplished by utilizing set screws to lock the “L” bracket in place at the desired location. The set screws are designed to be tightened sufficiently by hand. All of these modifications were made keeping the chair’s folding ability in mind.

Testing Results

We took the folding chair to Avonlea for a functionality test and to receive any requested design changes. Even before the final iteration of the folding chair Avonlea was able to operate the chair with little effort. This made us realize she did not need more alteration to the product to accompany her abilities. Both Avonlea and her mother were very pleased with the chair, Avonlea was very enthusiastic when she test drove the chair.

For the raising chair a fitment test was not necessary as the previous team actually obtained the seat part itself from the family. We instead had to do extensive testing on the motors and motor kit we were fabricating. This included hooking up all of our electronics to various measurement tools (DMM, oscilloscope) from these we were able to view the PWM signal output to compare our two different motor controllers. We also connected the oscilloscope to read what the HAL sensors were imputing to the motor.

Instructions for Safe Use

Folding chair:

Unfold the chair and make sure the locking mechanism engages. Set both parking breaks and make sure chair is stationary. Insert both back rest rods and lock all 4 set screws ensuring the rods are locked in place. Insert the backrest into the rods and lock the supports. Place child in chair and fasten the lap belt, ensuring it is adjusted to hold the child in the chair. Turn the main power on and then release both parking breaks. Turn on power at the joystick and set desired speed level. It is now ready to operate by the joystick. Driving the chair through rough conditions, mud, water, uneven ground, etc can cause premature failure of parts and should be avoided.

When the 2 red lights on the power display are flashing, the chair must be charged. When charging move the main power switch to “o”. There will be a red light to indicate charging, when the light turns green the battery is fully charged. When storing the chair for extended periods of time move the main power switch to “o” and charge at least once a month. Do not store the chair in a power deficit.

When making adjustments to the back rest or foot rest double check that all fasteners are tight before using the chair. Do not forget to use the set screws on the back rest mounts that clamp to the back rest rods.

Project Summary/Reflection

We ended up ordering a new chair to accompany the existing chair. We did this because we wanted to make sure Avonlea received a chair. The existing chair was riddled with electrical issues and we could not guarantee a finished product, because of this we procured a second chair that had a high chance of being completed.

The other chair based off of the old groups chair was improved to actually be able to drive around. This took significant electronics work.

Semester

2023 Fall