A Soft Wearable Robot with an Adjustable Twisted String Actuator and a Two‐Stage Transmission Mechanism for Manual Handling Tasks

A manual handling task is one of the most common causes of back injuries, accounting for nearly 31.9% of the total work‐related injuries. To promote a safe working environment for workers, wearable robots (wearables) are rapidly emerging to fulfill various needs in human‐robot interactive tasks. Although numerous studies have successfully developed wearables to assist humans, they are often limited to supporting a single degree of freedom (DoF) of the human body with a single actuator. However, as humans tend to use multiple parts of their bodies, additional actuators and mechanisms to transmit force/motion are necessary to realize multi‐DoF, which increases the volume, price, and complexity of the wearables. To address these issues, a multi‐DoF wearable robot (WeaRo) with an adjustable twisted string actuator (ATSA) and a two‐stage transmission mechanism (2TM) is proposed. By introducing the novel ATSA and 2TM, the proposed WeaRo achieves multi‐DoF (lumbar and arm) with only a single electric motor and ATSA. Experimental results demonstrate that the proposed WeaRo effectively reduces the maximal voluntary contraction (%MVC) of lumbar, biceps, and triceps muscles by a maximum of 18.2, 29.1, and 27.0%, respectively without constraining users’ movements. Additionally, the fabric‐based design ensures a lightweight solution weighing 5.2 kg including batteries.