Design, modeling, and control of a reconfigurable rotary series elastic actuator with nonlinear stiffness for assistive robots

In assistive robots, compliant actuator is a key component in establishing safe and satisfactory physical human–robot interaction (pHRI). The performance of actuators largely depends on the stiffness elastic element. Generally, low desirable to achieve impedance, high fidelity force control pHRI, while required ensure sufficient bandwidth output force. These requirements, however, are contradictory often vary according different tasks conditions. order address contradiction selection improve adaptability applications, we develop reconfigurable rotary series with nonlinear (RRSEAns) for robots. this paper, an accurate model element (RSEE) presented adjusting principles investigated, followed by detailed analysis experimental validation. RRSEAns can provide wide range from 0.095 N m/∘ 2.33 m/∘, profiles be yielded respect configuration RSEE. overall verified experiments frequency response, torque which adequate most applications Specifically, root-mean-square (RMS) error results as 0.07 m transparent/human-in-charge mode, demonstrating advantages pHRI.