Ergonomic Design of an Assistive Propulsion System for Manual Wheelchairs.

Disability has always been a problem in developing countries like the Philippines. It is even aggravated by the environment and the lack of tools or equipment that can assist the handicapped people. Although there are equipment or assistive tools that designed specifically for use by these individuals, they contribute only a very small percentage of the total number of products that the handicapped people need. Survey was conducted to explore the current issues facing wheelchair users and to address the problems they experience in wheelchair usage. Results showed that users experience difficulty in propelling, steering, and transferring to and from the wheelchairs that result to discomfort and musculoskeletal disorders of the users. Thus, this research paper is focused on developing an ergonomic design of hand-cycle attachment that assists heavy-loaded wheelchair users especially when wheeling through long distances, challenging terrains and slopes. Features of the proposed design consist of synchronous propulsion system, foldability, mobility, adjustability, easy installation and stability by adding a stand that would keep the hand-cycle attachment in its upright position even when it is not in use. Clamping system and lever are also added to apply tensile and compressive forces to the wheelchair and can be rotated to maintain an ideal seat inclination of users in using wheelchairs. In addition to these, the design also includes a free-wheeling mechanism so the users will not have to apply force to the pedals all the time to keep the device running. The usability and effectiveness of the proposed handcycle attachment device was tested and validated using Rapid Upper Limb Assessment (RULA) tool. It was found that the use of the proposed device significantly decreased the risk of users for musculoskeletal disorders and provide ease and comfort for users compared to wheelchair use alone. Through the application of the principle of mechanics, propulsive force with the attachment device was computed to be significantly lower than the current tangential force applied by wheelchair users on the hand rims during propulsion. Respondents who tested the prototype also reported significantly lower propulsion difficulty scores. [ABSTRACT FROM AUTHOR]