Development of Wearable Finger Prosthesis with Pneumatic Actuator for Patients with Partial Amputations

Abstract

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.

Three DoF Cable Driven Parallel Manipulator with Self Sensing Nitinol Actuators

“…In recent years, there has been a growing interest in integrating smart materials, particularly shape memory alloys (SMAs), into robotic systems to enhance their performance and capabilities. Among SMAs, nickel-titanium (Ni-Ti) alloys stand out for their unique properties, including high energy density, biocompatibility, and shape memory effect, making them ideal candidates as actuators [1][2][3][4][5][6][7] in many applications in different fields, such as aerospace [8][9][10][11][12], biomedical [13][14][15][16][17][18], wearables [19][20][21][22], micro-systems [23][24][25][26], robotics [27][28][29][30][31][32][33][34]. There are not many works in the literature regarding manipulators with parallel architecture with SMA actuators.…”

Resistance Feedback for miniaturization of Shape Memory Alloys actuators

“…Many works in the scientific literature propose using SMA as actuators [1][2][3][4][5][6][7]. Many scientific works concern their applications in many fields, such as micro-systems [8][9][10][11], robotics [12][13][14][15][16][17][18][19], biomedical [20][21][22][23][24][25], wearables [26][27][28][29], aerospace [30][31][32][33][34].…”

Three-Degree-of-Freedom Cable-Driven Parallel Manipulator with Self-Sensing Nitinol Actuators

“…In recent years, there has been a growing interest in integrating smart materials, particularly shape memory alloys (SMAs), into robotic systems to enhance their performance and capabilities. Among SMAs, nickel-titanium (Ni-Ti) alloys stand out for their unique properties, including high energy density, biocompatibility, and shape memory effect, making them ideal candidates as actuators [1][2][3][4][5][6] in many applications in different fields, such as in aerospace [7][8][9][10][11], biomedicine [12][13][14][15][16][17], wearables [18][19][20][21], micro-systems [22][23][24][25], and robotics [26][27][28][29][30][31][32]. There are not many works in the literature regarding manipulators with parallel architecture with SMA actuators.…”