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Optimal Variable Stiffness Control and Its Applications in Bionic Robotic Joints: A Review

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Abstract

Variable Stiffness Actuation (VSA) is an efficient, safe, and robust actuation technology for bionic robotic joints that have emerged in recent decades. By introducing a variable stiffness elastomer in the actuation system, the mechanical-electric energy conversion between the motor and the load could be adjusted on-demand, thereby improving the performance of the actuator, such as the peak power reduction, energy saving, bionic actuation, etc. At present, the VSA technology has achieved fruitful research results in designing the actuator mechanism and the stiffness adjustment servo, which has been widely applied in articulated robots, exoskeletons, prostheses, etc. However, how to optimally control the stiffness of VSAs in different application scenarios for better actuator performance is still challenging, where there is still a lack of unified cognition and viewpoints. Therefore, from the perspective of optimal VSA performance, this paper first introduces some typical structural design and servo control techniques of common VSAs and then explains the methods and applications of the Optimal Variable Stiffness Control (OVSC) approaches by theoretically introducing different types of OVSC mathematical models and summarizing OVSC methods with varying optimization goals and application scenarios or cases. In addition, the current research challenges of OVSC methods and possible innovative insights are also presented and discussed in-depth to facilitate the future development of VSA control.

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Acknowledgements

This work was supported by National Key Research and Development Program of China [Grant No. 2020YFB1313000], National Natural Science Foundation of China [Grant No. 62003060, 62101086, 51975070], China Postdoctoral Science Foundation [2021M693769], Natural Science Foundation of Chongqing, China [Grant No. cstc2021jcyj-bsh0180], and Scientific and Technological Research Program of Chongqing Municipal Education Commission [Grant No. KJQN202100648].

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  1. State Key Laboratory of Mechanical Transmission, Chongqing University, Chongqing, 400044, China

    Yuanxi Sun, Yuntao Tang & Long Bai

  2. School of Advanced Manufacturing Engineering, Chongqing University of Posts and Telecommunications, Chongqing, 400065, China

    Jia Zheng

  3. School of Mechanical Engineering, Northwestern Polytechnical University, Xi’an, 710072, China

    Dianbiao Dong

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Sun, Y., Tang, Y., Zheng, J. et al. Optimal Variable Stiffness Control and Its Applications in Bionic Robotic Joints: A Review. J Bionic Eng 20, 417–435 (2023). https://doi.org/10.1007/s42235-022-00278-x

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