            Falls are a widespread occurrence among aging adults in nursing homes and in hospitals. Falls account for many of the physical injuries in aging adults and can often lead to complicated surgeries, including hip and knee replacements. These surgeries pose other complications that ultimately lead to more operations or even death in some rare cases.

            Previous research from our group focused on recording the reaction forces the subject exerts on the floor when transitioning from sit to stand as a way to estimate the control scheme the person uses to regulate the movement. The person was modeled as an equivalent mechanical system. Testing healthy individuals was done at first to estimate baseline values for the equivalent lumped spring and damping constants characterizing the model during the sit to stand movement. These parameters are important because they govern the motion control scheme. The spring allows the muscle to generate force, and the damper allows these forces to be damped so that the movement can be stabilized. A mathematical model was created from ordinary differential equations and optimized using Matlab coding. This model can be used to replicate the sit to stand movement as a generalized model for all subjects.

Testing patients that are at risk of falling and comparing their results with the mathematical model can show where the subject lacks when performing the movement. Knowing that these subjects are either lacking in spring or damping means that we know where they need help when completing the sit to stand movement. In order to help them, a sit to stand assistive device can be created that compensates for the subject’s lack of spring or damping force. This device can reduce the chances of falling while trying to stand and help healthcare professionals when aiding these patients. The product uses elastic bands with adjustable spring loading to give each subject just the right amount of extra spring force to help them stand up. Two systems are integrated where the spring and damping characteristics of the device can be changed separately. The subject can interact with the spring loading to commensurate the difference between the normalized mathematical model values and the subject’s values. This product is one of the few sit to stand passive, assistive devices allowing the patient to use lower body strength and very minimal upper body strength. The objectives of our device are to be adjustable, help people stand without falling forward, be relatively inexpensive, easy to use, and safe for a hospital environment.


Gravity Compensation Walker: Structure and Safety

Division / Sponsors: 
Aerospace, Bioengineering, Applied Mechanics, Design Engineering Division, Advanced Energy Systems, Manufacturing Engineering Division, Noise Control and Acoustics, Nondestructive Evaluation, Diagnosis, and Prognosis (NDPD), Nuclear Engineering Division, Process Industries Division, Fluids Engineering, Heat Transfer, Materials, Microelectromechanical Systems, Safety Engineering and Risk Analysis, Computers & Information in Engineering


Paper Proceedings: https://asmedigitalcollection.asme.org/IMECE/IMECE2020/volume/84478

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