Sturgeon

E-Walk

Project Overview

Sturgeon is creating a walker that will be lightweight and also provide stability when the user looses balance.  Disabled and elderly people usually have a hard time walking and require devices such as walkers and canes to stabilize themselves. These devices must be very light. This then creates a problem when the user begins to fall backwards as current walkers provide little support during such losses of balance.

Sturgeon has performed surveys that show that the the elderly strongly care about stability and safety when using walkers. Our main idea is to solve this issue by modifying a regular walker by adding lightweight magnets that would stabilize the walker when the user starts losing balance.  This extra stability would provide additional safety and support for the user. Sturgeon strongly believes that our walker would benefit many people from injuries and big medical bills.

Concept Overview

Sturgeon has developed a product called the E-Walk.  The first objective when designing the E-Walk is to balance users of the walkers.  To complete this objective the E-Walk will have electromagnets and the floors will be replaced with flooring that has magnetic properties.  The E-Walk will have pressure sensors in the grips that will be calibrated for each user to the force that they apply when the user feels like they are falling.  When the sensors are triggered, the electromagnets will be activated.  The next objective of the E-Walk is to be 10 pounds or less and have a holding force of at least 100 pounds.  The current average weight of walkers is 6 pounds and with the modifications the E-Walk will be no more than 10 pounds.  This allows the user to be as mobile as they currently are with the safety and security that the E-Walk brings.  The product needs a holding force of at least 100 pounds.  When the electromagnets are turned on there needs to be at least 100 pounds through the ground to be able to balance and stabilize the user.  The E-Walk lastly the needs to be user friendly.  The majority of the users will be senior citizens and are not accustomed to technology.  The E-Walk will be user friendly by being based off of instinct so the user will not need to think about activating the product.  Fig. 1 shown below  illustrates the SolidWorks drawings of the E-Walk.

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Fig. 1: The E-Walk

Proof of Concept


Sturgeon’s idea of proof of concept was created to show that the Electromagnetic Walker is a feasible idea. Sturgeon used an electromagnet with different surfaces to figure out the holding force.  The team figured out that the carpet had too much of an air gap to hold the walker.  With the carpet eliminated Sturgeon decided that linoleum was the surface to work on.  Once the surface was chosen the magnet was set to different voltages.  Sturgeon decided that the optimal voltage for the magnet to get the holding force that we need is around 36-48 volts.  With this knowledge in mind Sturgeon will set out to create/find a new electromagnet that will support the forces that the team needs.  A Picture of the proof of Concept can be seen below in Fig. 2.

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Fig.2: Proof of Concept Testing

 Detailed Design

To determine the force the magnets must exert on the walker to prevent falls, Sturgeon performed statics analysis on the walker.  Sturgeon used the mass and center of gravity of an average male for force inputs.  The maximum working angle the user may apply to the walker is 15 degrees.  With these assumptions, the walker was found to need a holding force of about 100 pounds, assuming no slip.

Stabilization is the major function of the E-Walk has been designed for.  Team Sturgeon also designed the E-Walk with easy maintenance in mind.  The fabrication and manufacturing has been completed to allow for easy access to the arduino, batteries, and magnets.  This will allow easy maintenance if the product fails.  Designing for cost was another important consideration.  When making the housing team sturgeon made sure that the material was lightweight and easily machinable.  Team sturgeon decided on aluminum.

Sturgeon select Magnetool’s EM-R2 electromagnets because they provided the most holding force while weighing under one pound themselves.  After much convincing, Magnetool agreed to give the magnetomotive force of their EM-R2 magnet, allowing an equation to be created to determine the maximum workable air gap, minimum reactive material, type of reactive material, and the holding force that would result from said variables.  The graphs from those calculations can be found in appendix F figure 3 and 4.  From those calculations, Sturgeon determined that one EM-R2 electromagnet can hold the required 50 lb at 48 volts with .1 inches thickness of 99.95% iron reactive material with a .06 inches airgap between the electromagnet and the reactive material.  An alternative is the use of metglas, a high permeability specialty material.  With metglas and the same electromagnet, the same results can be achieved with half the thickness of reactive material, .05 inches thickness.  The time response for electromagnets is negligible.  For all intensive purposes, electromagnets react instantaneously to applied current.

The pressure sensors were chosen based off of their high sensitivity, flexibility, and ability to cover a relatively large area.  Sturgeon has chosen two 25V lithium-ion batteries that will be wired in series to obtain a total of 50 V to run the electromagnets.  These batteries far exceed the amp-hours required to run the electromagnets for a reasonable period of time.  Because electromagnets do very little work, they require very little power while still providing high holding forces.  All of these engineering specifications, along with the required specifications, can be seen below in Table 1.

 

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Table 1: Required Specs vs Manufacturer Specs

The E-Walk will work on a simple circuit consisting of one microprocessor, three triple-A batteries, two 25-volt batteries, one potentiometer, one relay, two electromagnets and four pressure sensors. The four pressure sensors, controlled by a potentiometer, are sensor inputs to the microprocessor, and the output is a relay that will receive the 50 volts and control the two electromagnets. The microprocessor is powered by three triple-A batteries connected in series.

The E-Walk will be manufactured by Sturgeon in the team’s house. The manufacturing process is simple, as it only consists of modifying a regular walker. Custom mounts will be machined in the palmer machine shop.  There will be three different mounts that will be bolt on to the walker: the battery mount, the arduino mount, and the magnet mounts. Both the battery and the arduino mounts will be located in the middle body of the walker. The magnet mounts will be located in the bottom of the front legs of the walker.  The drawings of the mount can be seen below in Fig. 3.  The mounts will be attached through the use of TIG welding.  Wiring will be ran through the frame of the walker, as they are hollow. The pressure sensors will be wrapped around  the handles of the walker.

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Fig. 3: Mount brackets

Fabrication of the E-Walk


Once all the parts arrived the fabrication process of the E-Walk was fairly simple.  First the brackets for the magnets had to be machined.  These brackets were machined using a mill.  The brackets were connected to the bottom of the walker and then connected to the magnets with springs between them.  The springs are put in place to help level the magnets and provided the maximum holding force for the E-Walk.  After the brackets were connected the team started working on the wiring.  The team ran the wires through the inside of the walker, connecting everything internally.  Once all of the wires were connected the pressure sensors were placed on the grips using tennis grips.  All of the excess pieces including the arduino, circuit board, and connectors are placed inside an aluminum box that is bolted onto the side of the walker.  Figure 4 below shows the completed walker with all of the wires wired internally and the box concealing the arduino and circuit board.

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Fig. 4: Finished version of the E-Walk

Below is a video of the E-Walk. Team leader Anthony demonstrates how the E-Walk works, and provides a gripping demonstration, along with the use of the on switch.

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Meet the team


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Alexander Wittmann was born in Duesseldorf, Germany and has lived in Reno since the age of 10.  He is currently a senior in Mechanical Engineering and is planning on continuing his education in the field.  He currently works in the Mechanical Engineering department as an undergraduate researcher.  In his free time he plays video games and skies.

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Luis Cupas is an international student from Panama, and lived his entire life there until he came to the University of Nevada, Reno. He is currently a senior in Mechanical Engineering and is planning on going into the mining industry. He currently works at the Joe Crowley Student Union as an IT/AV Technician. During his free time he likes playing tennis and soccer, and reading about the latest car and technology news.

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Anthony Zunino was born in Nevada and attends the University of Nevada, Reno. He currently studies Mechanical Engineering as a senior and works as an Engineering Intern for LSP Products in Carson City. He plans on working in industry upon graduation. His hobbies include hunting, fishing, and reading.

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George Nicholas was born in Stockton, California, where he remained until moving to Reno to attend the University of Nevada, Reno.  He is currently a senior in mechanical engineering at UNR.  In his spare time he enjoys working on his 1974 chevy truck and 1973 motorcycle along with other side projects.  He is also working towards winning sontag as a first step in starting his own business.