Residences who stay in elderly/nursing homes are usually made up of people who use walkers and/or wheelchairs. Also according to cdc.gov, adjusted for inflation, “the direct medical costs for fall injuries are $34 billion annually. Hospital costs account for two-thirds of the total.” This is due to the high dangerous risk of residences traversing within their own home from the use of their walkers or wheelchairs. To reduce these costs within these homes means to reduce the residences’ falls and ensure their safety in doing so. The E-Walk, although an up-front investment, takes steps to ensure the safety of walker-users.
Team Extreme’s main design is to create a new lightweight walker that will utilize magnets to tether the walker to a magnetized floor to help prevent fall injuries. Team Extreme definitely believes that this design will ultimately help reduce the cost and injuries for the elderly.
Proof of Concept
Team Four is going forward with an electromagnet design. This Proof of Concept (PoC) will be used to prove that electromagnets can withstand the necessary forces applied to the walker in real world situations, such as providing a static grab bar for an elderly person to rely on. To achieve this, Team Four will first utilize computer programs such as SolidWorks to simulate the many forces in a Finite Element Analysis (FEA). Additionally, the SolidWorks analysis will help the team to determine an appropriate factor of safety to apply to the design in order to ensure the device will exceed the design requirement for a large and varied user group.
With the results from the FEA, the next step is to build a physical model. The team will construct one of the legs and apply various forces within the allowable range found through the FEA methods to prove that the device will perform as intended.
Team Extreme was meant to succeed Team Sturgeon’s work and overcome the obstacles the previous team had faced. So, the purpose of the project is very similar to Team Sturgeon’s, and that is providing static, safety measures for a mobile, dynamic walker system, therefore preventing any sort of fall-related accidents. If a resident or consumer were to feel a sense of disorientation while trying to sit down or while in high-accident areas of the home such as the kitchen or bathroom, the consumer could activate the device. What this device would provide is a static grab-bar for the consumer to steady themselves and maximize their time to recuperate in attempt to resist any fall-related accidents.
Harkening to the similarities of a regular walker, there is a slight mechanical difference at the bottom of the walker’s feet. As shown Fig. 1, the leg ends of the walker have a lip that is compatible to the shape of the fixed docking receiver channel. The feet of the walker would have the ability to engage the locking pin into the fixed floor docking receivers which are easy to install within the floors of a consumer’s home.
Figure 2 shows the entire, final assembly of the project in which the walker would latterly slide the device into place. The consumer would then align the custom-designed walker feet onto the docking receivers, aligning the locking mechanism. Then, the user could activate the device via squeeze actuator located at the handlebars of the device; therefore, locking the walker into place. This will then convert the mobile walking aid into a static grab-bar for the consumer to use around the home especially when located in high accident-prone areas such as the kitchen or bathroom.
With the walker now being a steady grab bar for the user, the user could then use the device to steady themselves to sitting onto their furniture, given the user installs the receivers on the floor in front of their furniture, or use the device as an anchor point in one’s home if the user were to perform other standing and stationary activities. All in all, this device would not only give the user a fall-resistant structure to hold on to but also peace of mind in terms of preventing hazards and emphasizing safety for one’s own place of residence.
The fabrication process was relatively simple because Team 4’s parts were mostly cylindrical. What this means is that for the majority of the time, a lathe and CNC mill were used to machine our parts. According to Team 4’s bill of materials, the parts were machined from round bars of cold rolled steel and a 1’x1’x1” plate of the same material.
First, the leg attachment that would be fixed on the walker and its housing pin would be fabricated first for it was the easiest to lathe. For the attachment, a 2 inch diameter round bar was shaped into a reduced pipe-flange style, parted from the original stock, and milled twice through its central interior in order for the attachment to achieve its characteristics for the receiving end. For the pin, a smaller 1 inch diameter round bar was machined to have the pin body, pin head, and pin tag. Figure 1a shows the results of the results of the leg attachment and the housing pin, and figure 1b shows the housing pin inside the leg attachment.
Figure 1a: The successfully fabricated leg attachment (right) and the housing pin (left).
Figure 1b: The tolerances of the housing pin versus the milled holes of the leg attachment were in order.
Next, the docking stations were CNC milled from a 1’x 1’ x 1” plate of cold rolled steel. The Solidworks program was uploaded into the CNC mill and automatically cookie-cut a circular hole and applied the necessary depths for the screws that would go into the floor and for the overhang to fix the leg attachment lip. Figure 2 exhibits one docking station, to be fixed on the floor, with its slight overhang which is compatible with the leg attachment lip.
Figure 2: One iteration of the fabricated parts. This is repeated for four times in fabrication.
Figure 3b: All of the fabricated, preassembly parts. (Not pictured: 2 additional docking stations – currently being machined)
The assembly process requires simple housing measures by sleeving the leg in the leg attachment and sliding the component to the docking station. Figure 4a shows the leg attachment easily able to slide into its receiving end where Figure 4b shows it through the walker holder’s perspective.
Figure 4: The leg attachment housed in the docking station.
Figure 4b: The leg of the walker and the leg attachment in the docking station (left) and the leg attachment simply on the walker leg (right) is pictured.
Then, for the pin to engage and disengage, a compression spring will be fixed for the pin to protrude, and tension cables will run through each leg which is actuated by a brake handle at the top of the walker. The pin will then engage into the floor, or into an additional baseplate shaped with the appropriate housing pin hole for the docking station (not pictured).
Testing and Results
After fabrication, testing the prototype was having tolerance fit tests and multi-directional force tests. In the end, testing also considered actually using the prototype for it’s designed purpose especially for demonstration and exhibition.
Tolerance fit tests included fitting the parts and measuring the clearances of each part to observe easy sliding. The drawings for the prototype state to allow for the standardized tolerance level of [units]. Measurements were conducted via caliper and then slide tested when engaging the subassemblies together.
The multi-directional force tests were planned to be relatively simple yet effective. A team member would take a stress gage, fix it onto the walker, and proceed to pull the walker when engaged into the floor, emulating grab bar usage. This is planned to test 10 iterations per team member and for a total of 50 testing trials to observe a good sample cluster for calculation comparison.
The tolerance fit tests were evidently successful. The parts were machined in a way that there was excess material and then was shaved down, measured using a caliper, shaved down, and measured again for the parts to be within Team 4’s standardized tolerance level. During slide testing, some of the parts had to be extruded out a little bit more in order for easy device engagement.
For the multi-directional force tests, each team member pulled with their weight force 10 times to emulate normal consumer usage. The max measured force used was two combined team members pulling a weight of 300 lbs of force to make sure the max 300 lbs of force guaranteed by the proof of concept was met. In the end, the test was successful, and the 300 lb force guarantee was met.
In summary, the project executed what it was designed to do, and that was to provide both a portable and static grab bar where the design matched the purpose of the project. The M-Walk was able to provide regular walker use and statically lock into place, offering easier and safer ways for the intended consumers to steady themselves in their own homes.
Not only was the product demonstrated on Innovation Day, but throughout the presentations, audience members were invited to use the prototype themselves and share their opinion on it. The general consensus within the multiple audiences throughout the day was that it was a clever idea on a relatively cheap way to assure safety for their family members. Some audience members shared how the problem Team 4 was tackling hit really close to home and expressed how the M-Walk could make it easier for its targeted users.
Some of the shortcomings were the designed measurements on Solidworks vs. actually fabricating them. The accuracy of the machines as well as the fabricator took into play as the parts did not exactly mesh perfectly together straight out of the machine shop. It is worth considering that the Solidworks measurements were not always representative of the parts manufactured. So, adjustments of the leg attachment and/or it’s corresponding docking station measurments were applied for ease of use of the product.
Other than that, there were no distinguishable failures when it came to the testing and implementation portion of this project.
Meet the Team
Emily Scholtes-Prue moved from Sacramento, California to Reno, Nevada in order to pursue a degree in mechanical engineering. She is currently in her senior year and expects to graduate with a Bachelors in Science and a minor in mathematics in the Spring 2017 semester. For the past two years, Emily has worked for the university’s “Introduction to Engineering Design” course and enjoys preparing freshmen students for the rigorous coursework associated with the various engineering programs. Emily hopes to pursue a master’s degree and a career in aerospace engineering.
Christopher Prior is originally from Truckee, CA and is a transfer student from Sierra College in Sacramento, California. He is graduating with a BS in Mechanical Engineering in May, 2017. His interests include drafting and designing projects in computer programs. He is currently very involved in health care and hope to obtain an engineering job in the field. He plans to begin his working career immediately after graduation and eventually return to school to obtain a Masters.
Jia Li is originally from China. He went to high school in China, and came to America right after graduation from high school. He studied at sierra college in California for two years, then transferred to University of Nevada, Reno. He is planning to find a job about designing something in America. He likes to work in front of a computer and to use programs to build or design something.
Originally from Henderson, Nevada, Jan Lao is a graduating Mechanical Engineering major from the University of Nevada, Reno with a minor in Mathematics and Warden of Phi Mu Alpha Sinfonia, Xi Delta Chapter of Fall 2016 – Spring 2017. So far, he has taken a couple of internships including Vision Mechanical Services and SouthWest Gas as well as a voluntary research position regarding multi-agent autonomous systems with Dr. Logan Yliniemi. He then plans to work a couple of jobs after college then take on graduate school afterwards.
James Kwon heralds from Las Vegas, Nevada and is graduating in May with a degree in Mechanical Engineering from the University of Nevada, Reno. Some of his hobbies include playing in the University Symphony Orchestra and spending his free time playing computer games. He plans to get a job after graduation and utilize all the skills that he learned to succeed in the work force.
Team 4 would like to thank the following for their continuous support and help in planning, designing, implementing, and fabricating our M-Walk Project.
George Nicholas – Project Sponsor
AJ Zunino – Project Mentor
Tony Berendsen – UNR Machine Shop Manager
The ME 452 staff