A substantial portion of workplace-related injuries stem from sprains, strains, and muscle tears, with a significant proportion occurring in the upper body, particularly the
shoulder. To address these issues, there is a growing interest in utilizing supportive devices like exoskeletons that often face challenges such as bulkiness, high costs, and parasitic forces, which have hindered their widespread adoption. Exosuits, an alternative to exoskeletons, offer potential solutions by primarily employing fabrics and leveraging the human body to transmit forces, eliminating the need for cumbersome and expensive external frames. A user study involving a passive-adaptive exosuit equipped with a controllable pretension spring showed a reduction in muscle effort while being limited to controlling only the system’s equilibrium position. It was theorized that the addition of a variable stiffness mechanism with controllable pretension and stiffness could eliminate observed issues and further increase muscle effort reduction, forming the need for
a variable stiffness mechanism. The vast majority of existing variable stiffness solutions are developed for use in joints as opposed to being designed for a linear motion and are thus not ideal for application in an exosuit. Additionally, the fusion of variable stiffness mechanisms and exosuits has not been studied extensively, with no studies using a variable stiffness mechanism capable of controlling both the stiffness and equilibrium position in an exosuit. This work presents the results of the user study, the development and testing of a variable linear stiffness mechanism for a linear motion capable of controlling the stiffness and equilibrium position, and the integration of said actuator in an
exosuit.