Design and fabrication of a soft wearable robot using a novel pleated fabric pneumatic artificial muscle (pfPAM) to assist walking

Abstract

Defects in walking can substantially impact individuals' quality of life. Utilizing wearable robots is one of the known methods to improve this daily activity for individuals with disabilities or limited mobility. In recent years, one of the challenges confronting researchers has been improving these devices' comfort and efficacy. This research aims to provide a lower-limb exosuit that aids in walking while being more comfortable and efficient than previous models in some certain respects. One factor that reduces the usability of these active wearables is the heavy and rigid structure of the force interaction mechanism and their inflexible actuators. This study's wearable robot benefits from a new Pneumatic Artificial Muscle (PAM) and a skeletal-free force mechanism, which, due to their innovative design and garment-like structure, when combined with a sensor network, weigh only 536 g. Also, the compressed air system is designed so that the user can quickly wear or remove it. The developed exosuit considerably improves the wearer's walking ability while remaining lightweight and comfortable. This claim has been checked and validated through numerous tests. The final results reveal that the user's posterior thigh muscles had an activity reduction of 7.4% in each complete gate cycle and 22.7% at peak time when using the exosuit compared with walking without the exosuit. Additionally, compared with the state where the exosuit was worn but inactive, the reduction was 16.2% overall and 63.9% at peak time. The motion cycle analysis also indicated that the system caused the user to take longer and more frequent steps than when walking without the exosuit. One of the reasons that has caused the performance of wearable robots to drop significantly as they become softer is the weakness of their actuators. In pursuit of this study's primary objective, a functional PAM was devised, which may have some of the most suitable features for such wearable robots. A contraction of up to 40%, a force-to-weight ratio of one thousand (with a weight of 44 g), a fabric-based structure for use alongside the body, low-cost production, contractibility at low pressures, and high controllability compared to its peer actuators are some of the soft contractile actuator features developed in this research.