Stroll
Stroll is a harness designed for body weight support therapy (BWST) to help in the recovery of workplace injuries. The project worked in collaboration with HabItec, an innovative group within the rehabilitation space. The task focused on the design of a harness system that could be used in ANDAGO, a frame that is used to provide uplifting force to the patient during therapy.
Problem with Existing Harness
HabITec outlined that the existing harness systems are very complex and time consuming to put on the patient. It is also large, uncomfortable and restricts their range of movement. HabITec provided a physical example of the 'Hocomo' harness shown in the images. This allowed for primary research on the existing products, allowing me to identify factors such as:
- Material: Nylon or polyester with plastic and aluminum clips
- Connection methods: Male/female clip-on straps, hook and loop fasteners and pulley straps
I intended to design a harness for the specific demographic of 55-59 year olds. The Hocomo harness was used as a foundation for the ideation phase. Key aspects I wished to improve upon are:
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Convenience and efficient setup
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Good ventilation or cooling system
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Easily cleaned for good hygiene
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Comfort by distributing body weight throughout harness
Ideation
Three different ideations were created based on the design intent and proposed to a member of HabiTec for feedback. The client showed a clear favour towards concept 1, which took inspiration from a baby stroller. The idea was that the design was modular, allowing the user to be transferred to the seat (module 1) with relative ease. The seat would then be attached to the base, allowing the user to walk around with their body weight uplifted by the seat. The idea was that the seat would take the majority of the uplifting force instead of on the patient, increasing the comfort of the device.
The major points of feedback and the solutions derived were:
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Device did not incorporate the ANDAGO frame
Solution: Bottom portion (modules 2 and 3) will be removed and instead only module 1 (the seat) would be used and connected with the ANDAGO frame.
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Potential psychological issue of adults being placed in a device similar to those used with babies
Solution: Inspiration of baby walker appearance would be discarded, keeping only the functionality
Re-design and Prototyping
Based on the feedback provided, only the seat component was kept from the initial concept 1 design. The sketch showcases a simplified seat, similar to a bike saddle. Ergonomics research was also included to determine dimensions suitable for the chosen demographic. An additional body harness was added to the design, where it would attach the seat to the ANDAGO frame.
A rapid low-fidelity prototype was then developed based on these changes. The prototype also allowed for physical testing, emphasising the following key points:
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Sizing and positioning of straps and mounts need to be relocated for balancing and range of movement
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The size of the mounts needed to be reduced to fit on the base of the seat
High-Fidelity Aesthetic Prototype
A high-fidelity prototype was then constructed from 600GSM white card. The model was used as a method of communicating the refined concept to the client for feedback. It is to be noted that the harness was also constructed during this stage using white card, nylon straps and buckles. The second photo in the slideshow depicts how the two modular parts are connected and worn.
Through self analysis and client feedback, three key points were raised:
The current model's straps were not firmly secured to the seat and harness. Hence, if any weight was placed on the chair, the harness would disconnect from the chair. Securing buckles and straps is normally achieved through methods such as stitching. The final design should therefore incorporate some method of properly securing the buckle to allow for ergonomic testing.
The chair straps were also permanently secured to the mounts, which would inhibit the ability to wash the straps separately. This could cause problems with hygiene and hence a method of detaching the straps should be found.
The three-strap system did not provide enough balance and hence a forth point of contact from the front would be beneficial.
Final Model Process and CAD Model
The final model was constructed from timber and the harness was made from heavy duty polyester cloth. For egonomics, the seat's thickness was halved from the initial prototype. Smaller 'D-ring' mounts were also used to reduce size and allow for an additional mount at the front of the model. Varnishing was completed over the seat's surface for durability and resistance against moisture.
Key changes made to the harness included an extension of the circumference of the harness. Rivets were used to secure the polyester webbing to the cloth harness. In addition, looped webbing was included at the top of the harness to allow for it to be firmly secured to the ANDAGO frame. Due to time constraints, the buckle system could not be properly secured as any pernament methods would prevent the harness from being able to adjust to different sizes. If continued in the future, a buckle system with a button-release adjustment system would be used to solve this issue.
The last four slides showcase a CAD model and drawings with dimensions for the design.
Final Product
The final product and demonstration photos are included in the gallery below. Overall, the product can be considered a success, where all criterion outlined for success. The device is convenient and relatively easy to put on with high adjustability. Due to its incorporation with the ANDAGO frame, the percentage of body weight uplifted can be adjusted to the patient's level. The seat design allows most of this force to be distributed across the seat's frame, allowing for comfort. The device can be disassembled and washed, ensuring high levels of hygiene. The device does not exhibit any sophisticated technology and can be priced reasonably with other competitors.
The ergonomics and ability to support different body weights cannot be tested in full due to the harness still not being secured properly. As stated previously, further testing is required after the button-release buckle system is implemented. Improvements could also be made to ventilation, as sweating issues with the large circumference of the harness could arise.
