Evaluating the Product

To ensure that our proposed rollator design is functional, it is important to evaluate the effectiveness of each subsystem on the rollator. Rollators are classified as a class 1 medical device under the FDA, meaning that the device is considered low risk and not subject to any specific standards from the FDA. However, it is still essential that the device is safe to use, thus requiring it to withstand expected forces during use and effectively solve the problem that it is addressing. Summaries of our testing and results are shown below but a more thorough description of our results can be found in our paper found here.

Internal View of Spring Tensioning

Spring Tensioning Evaluation

As described in our Product section, our rollator design aims to control the force required during braking. To show that our mechanism is effective, it is necessary to investigate the relationship between the amount of force required to brake at the different levels of spring tensioning. The experiment was performed by setting the rollator to the lowest tensioning level and then placing a weight on the center of the rollator. The tension level was then increased until the brake was fully off the ground. Several trials were performed with increasing weights. From our data, we determined that by increasing the tensioning level by one, the rollator can support an additional 6.37 pounds. We also determined that the rollator can support a maximum of roughly 35 pounds and still function normally. This means our design successfully accommodates an average load of groceries, which weighs around 20 pounds.

Experimental Data

Handle Modularity Evaluation

Users can utilize the RollControl rollator in one of two positions--either in the arched position or the upright position depending on their needs. The robustness of both positions was tested via FEA analysis within Solidworks to ensure the design could withstand the loads applied. Further testing was also done on the aluminum lock located at the rotation point. Previously, when the lock was 3D printed we observed repeated failure at that location. All parts are now made of aluminum.

All analysis was done with a 100kg force applied, which we determined to be the worst possible expected load on the device. We observe that in all testing done the observed stresses were under the yield strength of aluminum. Thus, the design can withstand forces applied to the device.

FEA analysis for arched handle position

FEA analysis for upright handle position

FEA analysis for inner lock

Resistive Wheels Evaluation

Test Setup for Resistive Wheels

The resistive wheels provide a braking force only when the rollator reaches elevated speeds. To test whether the eddy current braking wheels had a significant effect on the travel of the rollator, we tested our RollControl rollator design against the unmodified rollator. Since our rollator weighs more than the unmodified rollator, additional weight was added to the unmodified rollator. The rollators were then set on a 36" long aluminum sheet ramp propped up by 8" (13 degree incline) and released. We recorded ten trials each in which the rollators traveled straight. From our experiment, we observed a 10.0% decrease in travel distance from the rollator with eddy current brakes attached, demonstrating that the resistive wheels provided a statistically significant and perceivable resistive force at elevated rollator speeds.

Paper Report on Product Evaluation

More thorough explanations with related literatures are illustrated in

our final report! Please visit our report to learn about background research, motivations and evaluations on our product

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