A Closed-loop Control for Lower Limb Exoskeleton Considering Overall Deformations: A Simple and Direct Application Method

In this paper, considering overall deformations of the exoskeleton, we couple deformations relationship network (DRN) with fractional order viscoelastic (FOV) controller, proposing a novel DRN-FOV closed-loop control method, endowing exoskeleton with stable dynamic walking ability. Simply by utilizing only the data from the 6-axis force/torque sensors, the DRN can directly capture the mapping relationship between the foot reaction force/torque of the exoskeleton and its overall deformations. We introduce the FOV to eliminate disturbances and stabilize during walking tasks. The closed-loop control method directly compensates for the overall deformations of the exoskeleton and enables the wearer to walk stably wearing the exoskeleton. To assess the effectiveness of the proposed control method, walking tasks were effectively carried out on subjects with varying body parameters using the developed exoskeleton. The experimental results show that the DRN-FOV closed-loop control method accurately estimates and compensates for deformations, resulting in an improved dynamic walking ability of the exoskeleton with wearers.