Characterizing Actuator Force Profiles and Comfort Limits for Pediatric Exosuit Design

The development of lightweight, soft robotic pediatric exosuits offers a novel approach to enhancing motor function. Crucially, the efficiency and ultimate adoption of such devices depend on their safe yet useful functionality. This requires a thorough assessment of the forces generated by the actuators of the exosuit. We assessed the assistive forces of fabric-based pneumatic actuators designed for upper-extremity motion support in a pediatric robotic exosuit. Experiments used infant-sized upper-body test rigs to collect data on forces exerted on different body segments by two shoulder and two elbow actuator variants across multiple anchoring configurations. The selection of actuators (1-cell and 2-cell shoulder, and square and circular elbow) was informed by earlier work in terms of their reachable workspaces and ability to support smooth end-effector motion paths. Results confirmed that all tested actuator variants generated forces no greater than 32 N, remaining below the minimum threshold of force exertion for the infant body, a range deduced by the literature to be between 43 - 184 N. The results also revealed that the 1-cell shoulder and circular elbow actuator variants can strike a balance between force exertion and efficiency by providing appropriate mechanical output while exerting smaller amounts of force than other actuator variants. This effort contributes to identifying force limits for the infant population, offers guidance on suitable actuator selection, and outlines a design framework for pediatric wearable robotic exosuits.