Control of Adjustable Compliant Actuators

Machines

Berno J.E. Misgeld¹  Kurt Gerlach-Hahn²  Daniel Rüschen²  Anake Pomprapa² 

[1] Philips Chair for Medical Information Technology, RWTH Aachen University, Pauwelsstrasse 20, Aachen 52074, Germany;

关键词: compliant actuator;    adjustable stiffness;    impedance control;    rehabilitation robotics;    robust control;   

DOI  :  10.3390/machines2020134

来源: mdpi

【 摘 要 】

Adjustable compliance or variable stiffness actuators comprise an additional element to elastically decouple the actuator from the load and are increasingly applied to human-centered robotic systems. The advantages of such actuators are of paramount importance in rehabilitation robotics, where requirements demand safe interaction between the therapy system and the patient. Compliant actuator systems enable the minimization of large contact forces arising, for example, from muscular spasticity and have the ability to periodically store and release energy in cyclic movements. In order to overcome the loss of bandwidth introduced by the elastic element and to guarantee a higher range in force/torque generation, new actuator designs consider variable or nonlinear stiffness elements, respectively. These components cannot only be adapted to the walking speed or the patient condition, but also entail additional challenges for feedback control. This paper introduces a novel design method for an impedance-based controller that fulfills the control objectives and compares the performance and robustness to a classical cascaded control approach. The new procedure is developed using a non-standard positive-realcontroller designs are validated and compared in simulations and in a test bench using a passive elastic element of varying stiffness.

【 授权许可】

CC BY   
© 2014 by the authors; licensee MDPI, Basel, Switzerland.