A Compliant Elbow Exoskeleton with an SEA at Interaction Port

In recent years, various series elastic actuators (SEAs) have been proposed to enhance the flexibility and safety of wearable exoskeletons. This paper proposes an SEA composed of wave springs and installs it at human-robot interaction port. Considering the hysteresis nonlinear characteristics of the SEA, displacement-force models of the SEA are established based on long short-term memory (LSTM) model and T-S fuzzy model in a nonlinear auto-regression moving average with exogenous input (NARMAX) structure. Based on the established models, the SEA can effectively serve as an interaction force sensor. Subsequently, the SEA is integrated into an elbow exoskeleton, and a compliant admittance controller is designed based on the displacement-force model. Experimental results demonstrate that the proposed approach effectively enhances the flexibility of human-robot interaction.