WeLEx: Design, control, and performance of a novel portable lower-body occupational exoskeleton for power assist in load carrying

Lower-limb exoskeletons have been extensively studied, mainly for assisting or rehabilitating individuals with motor impairments. However, designing exoskeletons for power augmentation in healthy users remains challenging, as such devices must provide effective assistance while preserving natural human motion and comfort across diverse locomotion tasks. Most existing load-carrying exoskeletons focus on level walking, offering limited versatility for activities such as squatting or obstacle negotiation.This work presents WeLEx, a portable occupational lower-limb exoskeleton weighing 32kg for load-carrying assistance. The device features an innovative hip-knee cable-driven differential actuation system in the sagittal plane, which allows cooperative torque sharing between joints, reducing distal mass and mechanical encumbrance while maintaining effective assistance. The mechanical design, which combines a 12 DoFs rigid kinematic structure and an under-actuated joint system, is detailed, along with a control approach capable of being used for multiple locomotion activities and variable load conditions.The performance of WeLEx is assessed through a series of functional tests involving forward walking, squatting, and obstacle negotiation under various payloads. Results demonstrate that the exoskeleton can effectively assist multiple locomotive tasks while supporting loads up to 50kg, highlighting its potential as a versatile occupational device that helps in filling the gap between task-specific prototypes and existing commercial systems.