The use of the Series Elastic Actuator (SEA) system as an actuator system equipped with a compliant element has contributed not only to advances in human interacting robots but also to a wide range of improvements in the robotics area. Nevertheless, there are still limitations in its performance; the elastic spring that is adopted to provide compliance is considered to limit the actuator performance thus lowering the frequency bandwidth of force/torque generation, and the bandwidth decreases even more when it is supposed to provide large torque.
This weakness is in turn owing to the limitations of motor and motor drives such as torque and velocity limits. In this paper, mathematical tools to analyze the impact of these limitations on the performance of SEA as a transmission system are provided. A novel criterion called Maximum Torque Transmissibility (MTT)is defined to assess the ability of SEA to fully utilize maximum continuous motor torque. Moreover, an original frequency bandwidth concept, maximum torque frequency bandwidth, which can indicate the maximum frequency up to which the SEA can generate the maximum torque, is proposed based on the proposed MTT. The proposed MTT can be utilized as a unique criterion of the performance, and thus various design parameters including the load condition, mechanical design parameters, and controller parameters of a SEA can be evaluated with its use. Experimental results under various conditions verify that MTT can precisely indicate the limitation of the performance of SEA, and that it can be utilized to accurately analyze the limitation of the controller of SEA.
Safe rendering of high impedance on a series-elastic actuator with disturbance observer-based torque control
Fraunhofer Institute for Production Systems and Design Technology (IPK)（弗劳恩霍夫生产系统与设计技术研究所（IPK））；Daegu Gyeongbuk Institute of Science and Technology（大邱庆北科学技术院）
Design and Control of a Compact Series Elastic Actuator Module for Robots in MRI Scanners
Department of Electrical Engineering and Computer Sciences, University of California, Berkeley（电气工程与计算机科学系，加州大学伯克利分校）；Department of Mechanical, Aerospace, and Industrial Engineering, The University of Texas at San Antonio（机械、航空航天与工业工程系，德克萨斯大学圣安东尼奥分校）；Department of Mechanical Engineering, University of California, Berkeley（机械工程系，加州大学伯克利分校）
Series-Parallel Integrated Nonlinear Elastic Actuator applied to the lean motion of a bicycle simulator
Institute of Automatic Control, RWTH Aachen University（自动控制研究所，亚琛RWTH大学）；Demcon Life Sciences & Health（Demcon生命科学与健康）；Hapticlink Technologies（Hapticlink技术公司）；Department of BioMechanical Engineering, Delft University of Technology（生物机械工程系，代尔夫特理工大学）；Department of Rehabilitation Medicine, Erasmus MC（康复医学系，埃因霍温麦斯特大学）
Dept. of Aeronautics and Astronautics（航空与宇航系）；Massachusetts Institute of Technology（麻省理工学院）；Independent Researcher（独立研究者）；Department of Electrical Eng. and Computer Sci.（电气工程与计算机科学系）
Modeling and control of a cable-driven series elastic actuator
Institute of Robotics and Automatic Information Systems, Nankai University（机器人与自动化信息系统研究所，南开大学）；Tianjin Key Laboratory of Intelligent Robotics, Nankai University（天津智能机器人重点实验室，南开大学）
Impedance control of a cable-driven SEA with mixed $H_2/H_\infty$ synthesis
Institute of Robotics and Automatic Information Systems, Nankai University（机器人与自动信息系统研究所，南开大学）；Tianjin Key Laboratory of Intelligent Robotics, Nankai University（天津智能机器人重点实验室，南开大学）
