Fully assembled in early December 2021, the first physical prototype of the device featured aluminum and plastic components, all machined or 3D printed by the team members. This first prototype was intended to verify several aspects of the design before moving forward with the development of an adjustable loading system. Thus, this iteration did not incorporate the capacity for adjustable loading and instead served as proof of concept for the other features of the device and the system as a whole. The obvious weak link in the system was the prototyped plastic hinge, which failed (as anticipated) during initial testing. Team members noted little to no loading occurring in the front poles, and planned a redesign eliminating much of the anterior portion of the device to slim down the product. The adjustable height telescoping poles proved to work as intended, but would require shortening. The seat was unable to be fully tested due to poor alignment once the device was secured to the body, a problem that would be remedied in subsequent iterations. The first prototype also indicated that the team would need to create a custom harness attachment system, as the elasticity of the off-the-shelf version used here added slack to the system and made walking difficult as the device lagged behind the user's movement (see video below).

With the seat mostly untestable up until this point due to excessively posterior placement, the next iteration featured a new 3D printed seat mounted further forward on the device. This finally allowed us to effectively 'sit' on the device while wearing it. The upward pointing harness brackets were traded out for slots milled directly into the semicircular frame to decrease risk of injury from the protruding metal. The angled cross brace reinforcing the footplate and the telescoping poles was never fabricated using pipe stock as originally designed (seen in the photo render above) and was instead created with a cheaper and more easily manufacturable flat bar stock.

Our nearly final iteration of the device was constructed using professionally machined aluminum parts in combination with our in-house 3D printed foot plate and custom cast foam seat. All verification and validation testing was conducted using this prototype, details of which can be viewed on the testing information page. For the safety of the team members, our first trials utilized a cane in conjunction with the device. The device in the photo was assembled from a combination of new and old parts for customer validation, because the upper semicircular frame was unavailable due to machinist error. For physical testing, the updated frame was added and the upper hook and loop strap shown in the photo was exchanged for an easy release canvas belt.

Fully assembled, this prototype weighed less than 5 pounds!