Development of a Mobility Assistive Device for Sit-to-Stand

Abstract

The aim of the overall research is to investigate the motion of a wheeled mobile robot in an indoor (structured) setting while following a given trajectory. An example of application for this research project would be automated maneuver of a smart power wheelchair in a medical health care setting, such as a hospital, which will benefit Canada. For this specific research project the aim was to investigate mobility of an assistive device for Sit-to-Stand (STS) operation and walking. A rehab robot was developed and was attached to a wheeled mobile robot to accomplish STS operation and to walk a patient for rehabilitation. Four major phases of this project are: (i) design of the rehab robot, (ii) development of control algorithm, (iii) experimentation, and (iv) navigation of the mobile robot and the rehab walker (robot). In order to design the rehab walker/robot, an intensive literature review was accomplished on reported research work for Sit-to-Stand (STS) and smart walker design for lower limb rehabilitation. Later, conceptual designs were suggested for selection process. One of them was selected to be the mechanical final design, and was designed in detail. Finite element analysis (FEA) was performed, before a prototype was fabricated. Due to different lift methods for STS operation, four different algorithms were developed which can be put into three classes: arm-pad support lift algorithm, handlebar support lift algorithm, and belt support lift algorithm. A friendly interface that governs the communication between users and the device has also been developed. Several participants tested the algorithms and answered a questionnaire. The results were collected and analyzed qualitatively and quantitatively. It showed that designed algorithms helped in STS process, and was able to find the comfortable position for each user within a reasonable time. User experiences were reported to be generally good, and the rehab robot reacted “smartly” depending to detected user intentions. Hence, it can be concluded that major design goals for the rehab robot had been achieved. After the rehab robot had been fully developed, it was attached to a wheeled mobile robot and went through a set of tests to determine whether a previously developed FLB (Fuzzy Logic Based) algorithm was appropriate for this project. The results showed that the FLB algorithm successfully reached its pre-set goals and avoided obstacles on its way. In summary, this project contributed in lower limb rehabilitation and design of a smart walker. It intensively studied current research and projects, designed a rehab robot and four control algorithms to help people in both STS and walking process. Experiments had also been implemented, and results indicate the effectiveness of control algorithms and the predesigned FLB navigation algorithm. According to the results, this project achieved original goals to assist people in rising up and walking, and it also navigated to pre-set goals successfully. However, more research is still needed for marketization purpose, such as collect, more test data to optimize threshold settings of control algorithms, and develop a better navigation algorithm that has a higher degree of comfort.