System Breakdown and Low-Fidelity Testing

Our product takes inspiration from the benefits of aquatic therapy, while being a land-based solution. There are many benefits of aquatic therapy including an improvement in mobility, circulation and substantial pain relief. Outside the pool, these benefits can be matched with engineering solutions:

From this, 3 subsystems were derived for the final product. The main system of the device simulates the buoyant forces in water through mechanical offloading of the hips. Next, the first subsystem of the device simulates the high temperature environment of the pool through a far infrared heating system. Lastly, the second subsystem of the device simulates hydrostatic pressure through physical compression of the hip musculature

In the Spring and Fall terms of 2021, we worked on starting to pull together each of these subsystems.

Low-fidelity Prototypes: Attachment Point Testing

Firstly, we conducted some low fidelity testing with numerous upper and lower body attachment sites were tested with low-fidelity harnesses and braces.

The primary criteria during testing was the ability to carry vertical load and safety. Secondary criteria included difficulty of wear, discomfort, and compatibility with the other two subsystems.

• The upper body attachment points included the waist and lower back using a climbing harness as well as a lower back and lat support brace.

• Both solutions introduced considerable slipping as well as constriction discomfort to the midsection

• The lower body attachment points, including the pelvis, knee and mid-thigh encountered similar issues

• Slipping under load was occurring and sensitive areas like the pelvis compromised the ability to apply considerable force

From this, we were able to determine our ideal locations for attachment: the armpits for the upper body, and the foot for the lower body.

Gait Detection in Offloading

Another important aspect of our system was the ability to dynamically engage with our vertical offloading system, such that it should only be engaged when the foot is contacting the ground and carrying weight. This is when the affected hip will experience the most force. This means that the offloading system should turn on at heel strike, and deactivate at toe-off during the swing phase of the gait cycle.In order to do this, we would require some sort of sensing system to detect gait. A diagram of the gait cycle along with when actuation should be engaged is seen in the following.