PROTOTYPE OF BELLOWS-SHAPED SOFT PNEUMATIC ACTUATORS FOR THE DEVELOPMENT OF A MIRROR THERAPY SYSTEM

• Main Author: Harits Muhammad, R
• Format: Final Project
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/50041
• Institution: Institut Teknologi Bandung

Hand paralysis is one of the consequences of neuromotor impairment commonly found in stroke patients. To restore motoric functions of the hand, patients are encouraged to undergo physiotherapy, in which one of the most effective methods is Mirror Therapy (MT). MT is a technique where patients synchronize exercising their abnormal extremity whilst–at the same time–using visual stimuli from the reflection of the normal extremity. This practice should be accompanied by a therapist. However, the number of therapists in Indonesia is insufficient. As such, an independent approach to MT requires the help of an assistive robotic device that aids in repetitive motion. This device must allow safe and comfortable interactions with the user, have a flexibility high enough to be compliant to the characteristics of hand kinematics, and move smoothly when actuated. Soft Pneumatic Actuators (SPAs) are components from the field of soft robotics that have recently made a surge in physical rehabilitation. SPAs are made of deformable material and uses pneumatic pressure as its medium. A type of structure known for its capability in uniaxial deformation is bellows. Bellows are cylindrical with a certain number of folds called convolutions. The actuation behavior of bellows is obtained by testing different variations of convolution density and pressure using both numerical and experimental methods. Bellows with 0,4 convolutions/mm were found to have optimal results, and nonlinear behavior was observed for higher pressures. To facilitate finger movement in physiotherapy, a bellows-shaped SPA must conform to the needs of normal hand kinematics. Flexion-extension motions of the hand were recorded with motion capture and processed to secure the trajectory needed as reference for the design of the SPA. Then, a prototype for the assistive device is made. The fabricated SPA is evaluated by comparing the joint angles of both the normal hand kinematics and the hand kinematics generated by the SPA. It showed that they were both similar, quantified by a percentage that depends on the elongation of the SPA in question. This research exploits the unique capabilities of SPAs, in which bellows–as a structure known for its means of elongation–can be implemented for hand therapy.