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Project 9: Adaptive Walker, Smaller


This project involves designing a lightweight, adjustable, custom walker, similar to a gait trainer, for a 2-year old girl with Cerebral Palsy.  The walker must be easy for her to move around.



Alex Harrison, Charlie Ledford, Mason Reid, Joel Roberson

Problem Statement

The problem our team will be solving for this project will be designing and building a small walker to help a 2-year old girl with Cerebral Palsy walk around.  She has tried other walkers before, but the main problems that she runs into when using these walkers is 1. She is unable to move the walker around, and 2. She uses her arms to hold herself up on the walker so that she is not using her legs to move around.  Because of these problems, our team is tasked to design a small walker that is lightweight and easy for her to move around in, and has better arm support so that she does not feel inclined to try and hold herself up as much when moving around.  Also, the walker needs to be able to allow her to easily hold herself upright without requiring her to grip onto things because she has a hard time gripping onto things.

Design Specifications

Because of her condition, there are many specific design specifications and safety considerations that must be applied to this project to insure a safe and easily usable experience.

Design Specifications:

  1. Lightweight and easy to move around in
  2. Does not allow her to fall backward out of the walker, or any other direction
  3. Needs to be moveable on hardwood floors
  4. Must be able to support her weight and height of 21 Lbs and 32.09 in.
  5. Adjustable design that allows her continued use of the walker as she gets older


Background Research

Cerebral Palsy is a congenital disorder due to abnormal brain development before birth.  The main symptoms of this disorder include exaggerated reflexes, floppy or rigid limbs, and involuntary motions.  Because of these symptoms, young children with Cerebral Palsy often have a hard time walking without a walker, and traditional walkers usually do not provide enough support or features for them to take advantage of.  Here are a couple of walker designs meant specifically for children with Cerebral Palsy that our team has taken some inspiration from.  The main features from these walkers that we want to implement in our walker are the harness system that helps to secure the child to the walker, and the adjustable height that can be seen in the second picture with the hand screw.


Concept Design 1

This design is a multi-functional device designed to be a walker and standing device. The child is not strong enough to walk or support her full weight, and this is designed to help incrementally load her full weight onto her legs. The seat of the chair can be angled to allow her to rest some of her weight on the chair while allowing her legs to support her as well. the frame would be made out of aluminum allowing for it to be very lightweight and mobile. The tray, seat of the chair, and armrests would all be able to be removed and replaced with ease allowing for plenty of room for the child to grow and the walker to adapt.


Concept Design 2


This concept is based on the design of a traditional walker but implements some specific design elements to support and grow with her properly. This includes adjustable legs and locking wheels to change as she grows and allow it to be stationary if needed. It also includes a removable tray, seat, arm braces, and back brace. These provide her with an area to use if needed, a seat to rest or to support her, the arm braces ensure that she does not have to grip the walker, due to weaker grip strength and the back brace keeps her from falling and allows partial support if needed while walking. This will also be made of aluminum and other lightweight materials to ensure she can move the implement.


Concept Design 3

This design primarily takes structural integrity and safety into mind.  The two circular rings used to connect the four legs provide ample structural support for the walker and the child in the seat, and they also prevent the child from possibly falling over.  The legs are also spread out in order to minimize the risk of the walker falling over while the child moves the walker around.


Selected Concept Design

Based on our decision matrix, our selected concept design to move forward with is Concept 2.

Note: Our final design ended up being something completely separate from any of these designs, after further discussion in our team.



Decision Matrix

Overview of Selected Design

Our selected design was chosen based on four main factors: weight, safety, adjustability, and cost.  Here is how we believe our design meets or exceeds our requirements for each category:

  • Weight – We have decided to use aluminum Schedule 40 6063 for the frame of the walker.  This allows for a strong yet lightweight base, providing good mobility for our client.


  • Safety – We have created a design that surrounds the user and prevents the possibility of falling out of the walker.


  • Adjustability – We have built our walker with long-term adjustability in mind.  Our design allows for adjustability in the position of the saddle using tension straps, adjustable arm bars, and a fully adjustable upper platform.


  • Cost – In order to minimize costs, we have chosen to go with aluminum as our metal of choice, which is very cost effective for our use case.


  • Note: We found a stainless steel material in the shop that we used instead for most of the walker.  It was still relatively lightweight and provided a much stronger foundation for the seat.


Describe Design Details

  • Frame – The frame of our walker consists of pieces of Schedule 40 6063 aluminum pipe, with an outer diameter of 2.38 inches and an inner diameter of 2.08 inches.  The top part of the frame will have a slightly smaller diameter to allow for an adjustable height.  The height will be adjustable using a threaded hand screw on each side.


  • Wheels – The rear wheels of the walker are rubber wheelchair wheels that have a diameter of 12 inches.  The front wheels of the walker are swiveling caster wheels with brakes on them that will allow for turning, and they have a diameter of 4 inches.


  • Saddle – Our saddle will be suspended using tension straps from the top part of the frame, and it will have leg holes and a harness system to prevent the user from accidentally falling over.


  • Armrests – The armrests will provide arm straps to help keep the user’s arms in place, a curvature that will be comfortable for the user, and an adjustable handle for holding on when needed.


  • Note: Our saddle ended up being an adjustable seat instead of a harness system.  Also, stainless steel was the main construction material, instead of aluminum.

Engineering Analysis 1

Looking at the vertical supports, we found a stress ratio greater than ten leading us to use a long column analysis for buckling and critical load, the critical load for the material and geometry is vastly larger than and force that might be exerted by the weight.

Engineering Analysis 2

For the walker to be adjusted , we use screws put into the vertical supports slots that will be subjected to stress, for our selected material of screw, shear strength 1590lb, no load subjected by the child will cause them to fail.

Engineering Analysis 3

Looking at forces exerted on the extreme ends of the top of the walker, we calculated possible moment that could cause walker to fall forward or backward (rotate about the child), to be sure that the child could not fall by irregularly pushing around her bodyweight. We concluded that no reasonable force exerted by her will cause this to happen.

CAD Drawings

Bill of Materials

Document Fabrication Process

Fabrication Process:

  1. Measuring:
    • The first step of the fabrication process involved making accurate measurements and cuts for the bottom part of the frame, the top part of the frame, the handles, the arm rests,  the seat mount, and the seat itself.  We also drilled holes into everything that was going to be bolted in to the main frame.
  2. Welding:
    • The next step of the manufacturing process was welding.  Using the great team in the machine shop, we welded the top and bottom piece of the frame for a strong base, and we also had brackets welded onto the handles and seat to allow for adjustability in the walker.
  3. Safety Inspection:
    • The last and most important part of the fabrication process was ensuring that the walker was safe for Josie to use.  We sanded down any sharp corners that could be found on the walker, and placed thick safety padding over any brackets and corners to make the walker as safe as possible.


Testing Results

In testing, the seat of the walker was able to hold 165 Lbs without a problem at all, and I would guess that it would be able to take much more weight as well.  The walker rolled smoothly and the caster wheels worked well for turning.  Overall, the walker works very well.


Completed Design Photos

Instructions for Safe Use

  1. Armrest Adjustability:
    • To adjust the position of the armrest, remove the padded armrest using the velcro straps.  Then, use a 9/16 inch wrench and allen key to remove the two bolts holding the wood to the frame of the walker, and move the armrest to the desired position.  Then, use the bolts to fasten the wood into place.  Finally, tighten the padded armrest back into place using the velcro straps.
  2. Height Adjustability:
    • To adjust the height of the walker, use the M10 allen key and loosen the two bolts holding each side of the top frame into place in the aluminum rod.  Then, adjust height accordingly and use the screws to lock the top part of the walker into place.
  3. Handle Adjustability:
    • To adjust the handles, remove the two screws on each side of the bracket of each handle and move the handles to the desired position.  The handles can be placed on the walker horizontally or vertically, depending on which one works better.
  4. Seat Adjustability:
    • To adjust the seat, remove the two bolts holding the seat into place using the 9/16 inch wrench and the allen key.  Then, move the seat to the desired position and replace the two bolts.
  5. Brakes:
    • To activate the brakes on the walker’s caster wheels, press down on the tab sticking out of the wheels until it locks into place.  This will restrict both turning and rotation in the caster wheels.

Project Summary/Reflection

This project helped us learn a lot about the engineering design and fabrication process.  We feel very grateful and lucky to be a part of this project, and we hope that we were able to create a safe and useful walker for Josie for many years to come.



2024 Spring