Springs
The choice of springs used within our device is critical to its proper functioning. The design of our device limits the final extended length of each spring but each spring must deliver an appropriate force. Additionally, we need to understand how the length of the spring can be used to determine the force for the digital interface.
Above you will the spring force diagram for one of our options. For all of this experiment, three different weights were applied to a spring for 100 trials and the displacement measured. The spring constant was found to be 135.9 N/m with an r² value of 0.999, calculated from the line of best fit. This spring can generate a maximum of ~5N of force.
structural stability
While our device is intended for use while sitting down, we want to ensure that all of our users will be safe. One of our primary concerns was that if a patient forgot they were strapped in and attempted to stand up while strapped into the device, the device would be unable to bear their weight and would break, causing further injury.
To validate the structural integrity of our device, we placed increasing amounts of force on the bar of rotation and measured the mm of displacement of the center of the bar. Fig. 5 shows the final point measured at 240 lbs, at which the bar still did not break. This indicates that the device should be structurally strong enough for our users, although further testing will be completed.
To validate the structural integrity of our device, we placed increasing amounts of force on the bar of rotation and measured the mm of displacement of the center of the bar. Fig. 5 shows the final point measured at 240 lbs, at which the bar still did not break. This indicates that the device should be structurally strong enough for our users, although further testing will be completed.
Page by Elaine Limqueco