Ergonomic Passive Dynamic Arm Orthosis for People with Upper Extremity Dysfunction

Abstract

People with muscular dystrophy suffer difficulties in everyday life due to reduced arm function. To solve this problem, various dynamic arm support (DAS) was developed. However, only a few of them is commercially available due to low marketability, and the available DAS has low functionality and usability. The main objective of the thesis is developing a compact DAS with high performance and transparency that can be fabricated using the entry-level 3D printer. However, in order to achieve all of these features, several issues have to be solved. First, a human has complex shoulder structure that makes shoulder joint displacement causing large misalignment between arm and orthosis. Secondly, the characteristic of the passive elastic actuator is far from the ideal spring. Thus actual produced torque is different from the desired torque. Thirdly, there exist only a few information about the relationship between the printing build parameter and the mechanical property of the fabricated part using the entry-level 3D printer. Therefore, the optimum design is hard to be done with the 3D printer. The main contributions of the dissertation are as following. Developed an ergonomic mechanism that enables the human natural movement with a simple structure by using the human motion characteristic. Increase assisting performance and energy efficiency of the DAS by designing a realistic model and proper usage condition of the passive elastic actuator. And construct a design guideline for optimal design and fabrication using the entry-level 3D printer By using all accomplishment of the above research, the SHR orthosis (an ergonomic passive DAS) is developed, which enable human natural movement and provide the proper assistive force with a simple structure. The performance and usability of the developed DAS are assessed by quantitative experiment and qualitative clinical trial. The result of the quantitative experiment demonstrates that the orthosis can reduce muscle activation level. And the clinical trial proves that the developed DAS can increase the motor function of the muscular dystrophy patients. Consequently, the SHR orthosis is expected to enable the independence of daily life of the muscular dystrophy patients.