Design of a low cost, low weight, aesthetically pleasing prosthetic knee

Abstract

Nowadays, the prosthetics industry is evolving and using more technological advancements in its prosthetics. It is using smart features such as microprocessors, to allow for a variable gait speed without any further adjustment. However, the problem remains that prosthetic knees are expensive, as well as heavy and not emotionally pleasing. This project aims to solve this issue by designing a prosthetic knee that is low cost, low weight and aesthetically pleasing. The basic design cycle was utilised as the methodology to tackle this problem. First, during the problem analysis stage, market research on existing prosthetics was carried out along with structured interviews with above knee amputees. The daily tasks of these amputees were ranked. Using this research, a Quality Function Deployment (QFD) was constructed along with a set of Product Design Specifications (PDS) to summarise the requirements needed for a prosthetic knee. Then, the next design stage was conceptual design where the functions of the prosthetic knee were determined using the Function Means Analysis (FMA) tool and a morphological chart. Using these tools, four different concepts were developed based on different means. After analysing all four concepts, two were chosen to continue on embodiment design. During the embodiment design stage, virtual three-dimensional (3D) models of the two concepts were created. The models were 3D printed to get a better idea of their functionality. Both solutions were analysed and one concept was selected. The harmonic drive concept progressed onto the detailed design stage. Specific parts were chosen and implemented into the design to create a prototype. The prototype was then tested to ensure it met the aims of the project. Towards the end of the project, a virtual library was created to allow prosthetists to easily formulate prosthetic knee solutions from already existing models, based on the needs of the amputee. Finally, limitations and improvements, with the intention of leading towards future research, were discussed.