A Wearable Soft Fabric Sleeve for Upper Limb Augmentation

Abstract

Soft actuators (SAs) have been used in many compliant robotic structure and wearable devices, due to their safe interaction with the wearers. Despite advances, the capability of current SAs is limited by scalability, high hysteresis, and slow responses. In this paper, a new class of soft, scalable, and high-aspect ratio fiber-reinforced hydraulic SAs is introduced. The new SA uses a simple fabrication process of insertion where a hollow elastic rubber tube is directly inserted into a constrained hollow coil, eliminating the need for the manual wrapping of an inextensible fiber around a long elastic structure. To provide high adaptation to the user skin for wearable applications, the new SAs are integrated into flexible fabrics to form a wearable fabric sleeve. To monitor the SA elongation, a soft liquid metal-based fabric piezoresistive sensor is also developed. To capture the nonlinear hysteresis of the SA, a novel asymmetric hysteresis model which only requires five model parameters in its structure is developed and experimentally validated. The new SAs-driven wearable robotic sleeve is scalable, highly flexible, and lightweight. It can also produce a large amount of force of around 23 N per muscle at around 30% elongation, to provide useful assistance to the human upper limbs. Experimental results show that the soft fabric sleeve can augment a user’s performance when working against a load, evidenced by a significant reduction on the muscular effort, as monitored by electromyogram (EMG) signals. The performance of the developed SAs, soft fabric sleeve, soft liquid metal fabric sensor, and nonlinear hysteresis model reveal that they can effectively modulate the level of assistance for the wearer. The new technologies obtained from this work can be potentially implemented in emerging assistive applications, such as rehabilitation, defense, and industry.

A Smart, Textile-Driven, Soft Exosuit for Spinal Assistance

“…Additionally, the device still contains rigid structures, which do not interface well with the human body, reducing the comfort and portability of the devices [24]. An examination of 52 wearable devices revealed that a mere 11% of them were classified as fully soft [22,23,[25][26][27]. Within the realm of fully soft wearable devices, flexible textile materials stand as the prevalent solution for ensuring a compliant connection with the user's body [28][29][30].…”

Experiences of patients who had a stroke and rehabilitation professionals with upper limb rehabilitation robots: a qualitative systematic review protocol

“… 12 It should be noted that the use of Exosuits in rehabilitation is a relatively new approach in rehabilitation robotics, and no comparison studies have been completed to date. 7 13 14 …”

“… An example of an upper limb exosuit robot described by Hoang et al 7 being worn by a volunteer. Note: The person shown in the picture is not a patient and was taken with the participant’s knowledge and permission.…”

“…The use of rehabilitation robots has grown over the past few decades,1 particularly for upper limb stroke rehabilitation, and the evidence supporting their use is also increasing 2 3. Several rehabilitation robots are available to assess and augment rehabilitation of stroke-impaired upper limbs under direct or remote supervision, including end effectors4 5 (figures 1 and 2), exoskeletons6 (figure 3) and exosuits7 (figure 4). The use of rehabilitation robots produces comparable results,8 and in some cases, such as when used by individuals with upper extremity hemiplegia, who have limited chances of spontaneous recovery after stroke, they could produce better results than those achieved by other routine therapy methods 2 3.…”

“…In contrast, the meta-analysis by Moggio et al found that exoskeleton robots are significantly superior to end effector robots in improving finger and hand motor function in patients after a stroke 12. It should be noted that the use of Exosuits in rehabilitation is a relatively new approach in rehabilitation robotics, and no comparison studies have been completed to date 7 13 14…”