Development of Wearable Finger Prosthesis with Pneumatic Actuator for Patients with Partial Amputations
Hyunho Kim,
Sujin Jang,
Phuoc Thien Do,
Chang Kee Lee,
Bummo Ahn,
Suncheol Kwon,
Handdeut Chang,
Yeongjin Kim
Affiliations
Hyunho Kim
Department of Mechanical Engineering, Incheon National University, 119, Academy-ro, Yeonsu-gu, Incheon 22012, Republic of Korea
Sujin Jang
Department of Mechanical Engineering, Incheon National University, 119, Academy-ro, Yeonsu-gu, Incheon 22012, Republic of Korea
Phuoc Thien Do
Department of Mechanical Engineering, Incheon National University, 119, Academy-ro, Yeonsu-gu, Incheon 22012, Republic of Korea
Chang Kee Lee
Material & Component Convergence R&D Department, Research Institute of Convergence Technology, Korea Institute of Industrial Technology, 143, Hanggaul-ro, Sangnok-gu, Ansan-si 15588, Republic of Korea
Bummo Ahn
Material & Component Convergence R&D Department, Research Institute of Convergence Technology, Korea Institute of Industrial Technology, 143, Hanggaul-ro, Sangnok-gu, Ansan-si 15588, Republic of Korea
Suncheol Kwon
Material & Component Convergence R&D Department, Research Institute of Convergence Technology, Korea Institute of Industrial Technology, 143, Hanggaul-ro, Sangnok-gu, Ansan-si 15588, Republic of Korea
Handdeut Chang
Department of Mechanical Engineering, Incheon National University, 119, Academy-ro, Yeonsu-gu, Incheon 22012, Republic of Korea
Yeongjin Kim
Department of Mechanical Engineering, Incheon National University, 119, Academy-ro, Yeonsu-gu, Incheon 22012, Republic of Korea
As the number of patients with amputations increases, research on assistive devices such as prosthetic limbs is actively being conducted. However, the development of assistive devices for patients with partial amputations is insufficient. In this study, we developed a finger prosthesis for patients with partial amputations. The design and mathematical modeling of the prosthesis are briefly presented. A pneumatic actuator, based on the McKibben muscle design, was employed to drive the finger prosthesis. We characterized the relationship between the actuator’s force and axial length changes with varying pressure. An empirical model derived from conventional mathematical modeling of force and axis length changes was proposed and compared with experimental data, and the error was measured to be between about 3% and 13%. In order to control the actuator using an electromyography (EMG) signal, an electrode was attached to the user’s finger flexors. The EMG signal was measured in relation to the actual gripping force and was provided with visual feedback, and the magnitude of the signal was evaluated using root mean square (RMS). Depending on the evaluated EMG signal magnitude, the pressure of the actuator was continuously adjusted. The pneumatic pressure was adjusted between 100 kPa and 250 kPa, and the gripping force of the finger prosthesis ranged from about 0.7 N to 6.5 N. The stiffness of the prosthesis can be varied using the SMA spring. The SMA spring is switched to a fully austenite state at 50 °C through PID control, and when the finger prosthesis is bent to a 90° angle, it can provide approximately 1.2 N of assistance force. Finally, the functional evaluation of the finger prosthesis was performed through a pinch grip test of eight movements.
