Millennial Walker A multi-functional, elderly assistance walker with improved posture, comfort, and folding capabilities.

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Sharyl Shields
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1 Millennial Walker A multi-functional, elderly assistance walker with improved posture, comfort, and folding capabilities. Background & Research Question There are many different styles and categories when referring to a walker. When talking about a walker, most people think about a four leg pipe frame with tennis balls on the tips to allow the legs to slide across the ground. The term walker could refer to many other options as well. There are four wheeled walkers called rollators. There are three wheeled versions of rollators. You can also find standard walkers with only two front wheels. Needless to say, there are many options in the market of walkers. But which of these is the best to use? There is no one size fits all solution for every person s need. However, with a few adjustments to the standard designs that are currently on the market, a safer, more comfortable, and more user friendly walker can be developed. This is our goal; to create a more ideal walker. Generally, when using a common walker, the user pushes it out in front of them, causing them to hunch over. This causes unnecessary strain on the back and can reduce the quality of life for the elderly user. Providing a way for them to still be mobile and allowing them to maintain proper posture is essential to solving this problem.

2 After interviewing and surveying walker users, a few other items were brought forward that the users want addressed: 1) brakes continually wear out and need to be maintained; 2) most walkers are too bulky and awkward for the elderly to fold and store on their own; 3) sometimes the users need to take a rest from walking and need another person to push them which is difficult with current walkers. We took these three issues along with improving the user s posture to create a next generation walker: the Millennial Walker. This project has been created in collaboration with Millennial Medical, the manufacturer of the Millennial In-Motion crutch, an industry leading crutch. Approach & Solutions Considered In the design of the walker, we considered the material, folding configuration, handle position, wheel type, and brake type to be used in the walker. A trade study was completed for each of the areas of design, in which different solutions were compared and considered for application on our walker. To choose the material to make the walker from, we considered the cost, material properties, and accessibility of the material to the design team. We considered aluminum 6061-T6, 4130 steel, aluminum 6063-T6, aluminum 2024-T3, and carbon fiber. Based on the comparison, a selection of either 6061-T6 Aluminum or 6063-T6 Aluminum was be made. In a discussion with the design project sponsor, it was understood that 6061-T6 Al is the same material that is used for their current products. In choosing how the walker should fold, we studied current walker and wheelchair designs. Many rollator walkers currently on the market fold into an awkward configuration in which the rollator cannot stand on its own and the handles extend away from the rest of the folded rollator. However, wheelchairs and certain walkers feature folding configurations in which the wheelchair or walker can stand on its own and still be rolled while folded. We looked at implementing a folding configuration similar to that of a wheelchair, in which the rollator folds by bringing the sides closer together while keeping all four wheels on the ground. The handle positioning on the walker was approached with a focus on ergonomics and posture. Studies in human ergonomics have shown that the natural position of a human wrist is maintained while the angle between the forearm and the hand is approximately 15 degrees. A handle was incorporated which places the user s hand in this natural wrist position. We also decided to add armrests to the walker to encourage good posture in the user. To accommodate a variety of armrest positions, the handle assembly was placed on a locking pivot. The wheels on the walker were considered based on the need for the walker to easily roll over small obstacles without getting stuck. By speaking with walker users and testing different size wheels, we determined that larger wheels were more desirable than the usual small wheels.

3 We considered 6-inch, 8-inch, and 10-inch diameter wheels. Additionally, we considered adding suspension to the wheels to assist in getting over obstacles. The types of suspension considered included springs, hydraulic shocks, and magnets. The brakes for our walker design were decided on by studying devices with similar wheels and comparing the braking mechanisms. Current rollator walker brakes were found to have a tendency to wear out both the brake and the wheel itself and were nearly unreplaceable. Various types of bike brakes including rim brakes and coaster brakes were considered. We also considered the use of disc brakes or band brakes. Description of Final Approach and Design The final decision approach considered the needs of the system as a whole. We considered how different features would interact with each other and what would be easiest to implement. Accessibility to aluminum 6061-T6 helped us to decide on aluminum 6061-T6 as the material of the walker. The design of the folding mechanism was done with two goals in mind. These goals were to have the walker able to lock into different widths as it was folded side to side and to have the walker able to fold compactly side to side. By considering these two goals, we designed a scissor type folding mechanism. The handles of the walker were designed to encourage the user to stand up straight while maintaining the natural wrist position. The handle was designed to fit the natural inclination of the wrist. We considered ways in which pivoting armrests with the ergonomic handle could be incorporated into an adjustable height walker. The final design of the handles and armrests incorporated a bar containing the handles and forearm rests extending from a gear which held the bar at the desired angle. The wheels of the walker were designed based on the principle that larger diameter wheels ensure that the walker will easily roll over small obstacles (thresholds, thick carpets, etc) without getting caught. However, the size of the wheels was limited by the height we wanted for the walker. To get a desired walker height while still allowing the walker to roll over small obstacles, we decided on 8-inch diameter wheels. We chose hard plastic wheels with rubber treads that would require no user maintenance and were suitable for the surfaces often experienced by walkers. For suspension, we looked at the benefits of suspension and the complexity of a suspension system. We chose to leave suspension off of the walker because 8- inch wheels could overcome the types of obstacles experienced by walkers without needing suspension. In addition, the design was greatly simplified by eliminating the additional weight and moving components a suspension system would require The brakes were chosen based on simplicity and maintenance needs. The final two options we decided to consider were rim brakes and band brakes. Band brakes proved to be simpler to incorporate and upkeep than rim brakes, so we chose band brakes over rim brakes.

4 The Millennial Walker incorporates many useful features that improve on current walker designs. The walker folds side to side and can stand independently while folded. The scissortype folding mechanism allows the walker to condense to less than 30% of its original width. The frame and many components of the walker are made of aluminum 6061-T6 due to its low weight and high durability. The folding mechanism also includes multiple locking positions for the user to adjust the width of the walker. The seat and backrest allow the walker to function as a basic wheelchair. The walker has four 8 wheels, which assist in rolling over obstacles. The rear wheels have band brakes, which are easy to operate and install. The front wheels include a resistance system which allows the user to set a comfortable rolling speed of the walker. The handles of the walker include attachment points for armrests, which allow users to get extra support from the walker. The handles also rotate, allowing users to select an angle that is most comfortable for them while maintaining a natural hand-wrist angle. The rotation of the handles also allow the handles to be rotated for easy pushing while the walker is used as a wheelchair. The handles feature 9 of vertical adjustment, allowing for a wide range of user heights. Testing Outcome Several different tests have been performed to ensure that the prototype of the Millennial Walker is safe to use and meets proper standards. There is an International Organization for Standardization (ISO) document that governs the category of rollators within the walker market (ISO :2005). This document outlines several tests to be performed on a rollator. The tables below list each test that has been performed to date. Table 1 lists the student project requirements, Table 2 lists the ISO requirements: Table 1. Student Project Requirements Project Requirements Tested to Date 1.a: 300 lbs. sitting Load Test Result Supports 350 lbs. 2.b: Folds to 80% of original, unfolded footprint Folds from 25.5 to 9 (~35%) 2.c: Entire walker weighs less than 20 lbs. 3.b: Users can be in height Weighs 17 lbs. Accommodates full range of heights mentioned.

5 Table 2. ISO Rollator Requirements ISO Requirements Tested to Date Numbers correspond to the sections in ISO : : Wheel Size Front Diameter: >=7.087 Wheel Width: >= : Stability Angle of tipping from horizontal according to: Forward Stability Test: 15 Backward Stability Test: 7 Sideways Stability Test: : Brakes Does it have parking brakes? Max brake grip distance: Running Brake Test: Walker moves <0.394 in 1 min 4.4: Handgrip Handgrip width: <= w <= : Folding Mechanism When in use, folding mechanism shall stay securely locked in position. Test Result All four wheels are 8 in diameter and 1 wide. Unloaded: Forward: 32 Backward: 45 Sideways: 30 Loaded with 50 lbs: Forward: 28 Backward: 24 Sideways: 7 It does have parking brakes. Grip distance: 2 Running Brake Test: 0.0 in 1 min Width: 1.5 Locking plunger pins are used to secure folding positions. Project Cost The current design of the Millennial Walker is a working prototype to demonstrate the concepts and ideas that will gain advantage over other walkers on the market. The budgeted cost to build this prototype was $3000. This funding was used to develop the ideas and components for the design. Actual cost for production could be reduced down to approximately $100 - $200 once specific component molds, tooling, and procedures were developed to produce several thousand units per year. Significance This project, to create a better walker, began with David OZ Osmond s simple observation that walker users always seemed hunched over when using their devices. As the owner of a medical company with a focus on ergonomics, the opportunity to help improve posture and eliminate discomfort became a specific focus. The Millennial Walker accomplishes this task by allowing the user to walk within the frame of the device instead of behind it. It also includes the ergonomic hand-wrist positioning seen in the Millennial Medical crutches.

6 In addition to the ergonomic improvements, the Millennial Walker also improves the braking system, folding and storage, and the ease of being pushed by another person. These were the three most common areas of complaint from walker users and the nurses and family members who frequently assist them. By designing from the ground up to overcome these concerns, the Millennial Walker is a next generation walker that was truly made with the user in mind. Acknowledgements OZ is the owner/coo of Millennial Medical. This project has been under his direction to meet the needs that he has seen in the market. He has worked together with the mechanical engineering student team from Utah State University to create and develop the concept and prototype of the Millennial Walker. References 1.

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