A Novel Design of Nonlinear Stiffness Actuator for Neurorehabilitation Robots

Abstract

Nonlinear stiffness actuator is a key point in the research field of neurorehabilitation robot. An actuator with good nonlinear stiffness characteristics can simulate the natural features of human interaction with the outside environment better, so as to achieve better rehabilitation training effect. In this paper, a novel nonlinear stiffness actuator was designed, mainly including two rollers, two couples of customized concave blocks with opposite directions, partial gear train, and a central torsion spring. Thereinto, the profile curve of customized concave block was mapped by a predefined deflection-torque trajectory with the natural interaction feature. And the central torsion spring was directly obtained from the existing products. Through this novel actuator, the human-machine interaction characteristics of “low load, low stiffness and high load, high stiffness” [1] can be realized.