Low-cost IMU-based motion capture system and pneumatic exoskeleton design for assistive applications

Abstract

Scientific and technological advancements have broadened the scope of exoskeletons, transitioning their role from augmenting human capabilities to offering vital support for patients in their daily lives. Assistive exoskeletons provide numerous benefits compared to conventional rehabilitation techniques. They are non-invasive, thus minimizing the surgical risks Furthermore, these devices enhance mobility and overall functionality, thereby fostering greater independence for individuals combating various diseases. The customizability of exoskeletons ensures that they can be tailored to meet the unique needs of each user, offering personalized assistance programs. Importantly, exoskeletons have the potential for home use, paving the way for continuous treatment beyond traditional clinical environments.

Unlike traditional exoskeletons, which typically consist of motors and rigid frames, the latest exoskeletons are lightweight and untethered, providing comfort and ease of use. Soft fabrics have emerged as a preferred choice for exoskeleton development due to their flexibility and ability to conform to the body's natural movements. To ensure that exoskeletons do not hinder the wearer's natural movements, motion capture technology is employed to analyze musculoskeletal models and human biomechanics comprehensively.

In this study, a low-cost IMU-based motion capture system was developed to analyze human motion. Validation of this system was conducted using a commercially available optical motion capture system, comparing RMSE values, joint angles, joint moments, muscle forces, and metabolism in simulations. Building on this technology, a pneumatic back exoskeleton was designed using chain mail fabrics to detect and correct improper back posture during lifting tasks. The effectiveness of the back exoskeleton is validated based on human motion data via OpenSim simulation. Additionally, the Tunable Stiffness Glove (TSG) was developed using the same soft fabrics to suppress wrist tremors in two directions, catering to patients with Parkinson's Disease or Essential Tremor. The efficiency of the TSG is analyzed using EMG and IMU sensors.