Week 4: (In-Lab) Dimensions and Brakes

Today, our team discussed the physical dimensions of the walker to begin building the aluminum structure of the frame. As seen in Figure 1, a rough sketch was drawn with the determined measurements according to the estimated height of an elderly individual. The "x2" written on the right hand side of the picture indicates the dimensions applying to both sides of the walker.

Figure 1: This displays the determined dimensions of the walker. This will be applied twice, for both sides of the walker. 

After considering these dimensions, the initial idea of using a brake system with a gripping mechanism to stop the wheels from moving forward, another approach was decided. With the discussion contributed from Dr. Seliktar, the idea of using a bicycle seat and pressure obtained from sitting could potentially lock the wheels. In this sense, an individual who has difficulty applying pressure or gripping their hands tight could stop the walker easily.

Aside from the physical building process, a few tests were determined and discussed in terms of actually testing this design for an individual. Some of which will be sketched out to determine the force applied to make the walker stop as well as from tipping when going down an incline. These tests include:

• the angle of the back: range of the angle allowed and what would be typical (referenced to someone standing up)
• getting up from a seated position: applying a set amount of weight to show it won't topple over
• find coefficient of friction: make an argument of why it is sufficient, why it is stable
• maximum weight it can hold on the bicycle seat (force applied)
• maximum angle that would cause walker to tip over: measure in different positions

Week 3: (Outside-Lab) Meeting with Dr. Seliktar

After a brief meeting with Dr. Seliktar, we had a few more ideas to work with. Previously, we had been planning on bolting the aluminum pipes together to construct the frame. However, Dr. Seliktar suggested using triangular steel plates to hold different parts together would be simpler and more effective, as seen in Figure 1. He also mentioned that PVC could potentially be easier to work with because there are elbow pieces that can easily hold different pipes together. We would like to use aluminum because it is lightweight, durable, and more aesthetically pleasing. Although, PVC would be a suitable backup should aluminum be too difficult to work with.

Figure 1: This figure displays the idea of the triangular steel plates that would be attached to the aluminum pipes.

Additionally, we talked with Dr. Seliktar in great length about seats and brakes. Dr. Seliktar seemed very fond of using a bicycle seat, as seen in Figure 2. This would enable the user to sit down and still move forward, but would not limit movement when the user walks normally. This is an intriguing idea, but would require the development of a more comfortable, cushioned bicycle seat that would be pleasant for older individuals to sit on for an extended period of time. Even so, it would be easier to install than a larger, folding seat.

Figure 2: This displays a sketch of the improved walker from the side, top and back views, with a bicycle seat attached instead of the original foldable seat proposed.

When brakes were discussed, Dr. Seliktar suggested that the brakes be locked as a default. The brakes would be connected to the grips, and gripping the handle would release the breaks and allow the walker to move (almost like a reverse bicycle break). However, this would be concerning for people with arthritis; would they consistently be able to grip hard enough to unlock the breaks? Instead, there could be a spring powered break right over the wheel that would stop the wheel whenever the user sits down or applies pressure downwards. This is the likely plan of action, given that it is easier to build and simple to use.

Ultimately, Dr. Seliktar gave us valuable suggestions that have given us a clearer picture of the walker we hope to build. We plan to consult with him throughout the duration of the term about any questions we might have about walker mechanics.