Abstract
Passive variable stiffness joints have unique advantages over active variable stiffness joints and are currently eliciting increased attention. Existing passive variable stiffness joints rely mainly on sensors and special control algorithms, resulting in a bandwidth-limited response speed of the joint. We propose a new passive power-source-free stiffness-self-adjustable mechanism that can be used as the elbow joint of a robot arm. The new mechanism does not require special stiffness regulating motors or sensors and can realize large-range self-adaptive adjustment of stiffness in a purely mechanical manner. The variable stiffness mechanism can automatically adjust joint stiffness in accordance with the magnitude of the payload, and this adjustment is a successful imitation of the stiffness adjustment characteristics of the human elbow. The response speed is high because sensors and control algorithms are not needed. The variable stiffness principle is explained, and the design of the variable stiffness mechanism is analyzed. A prototype is fabricated, and the associated hardware is set up to validate the analytical stiffness model and design experimentally.
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References
Ding H, Yang X, Zheng N, et al. Tri-co robot: A Chinese robotic research initiative for enhanced robot interaction capabilities. National Science Review, 2018, 5(6): 799–801
Hirzinger G, Bals J, Otter M, et al. The DLR-KUKA success story: Robotics research improves industrial robots. IEEE Robotics & Automation Magazine, 2005, 12(3): 16–23
Ham V R, Sugar T G, Vanderborght B, et al. Compliant actuator designs: Review of actuators with passive adjustable compliance/ controllable stiffness for robotic applications. IEEE Robotics & Automation Magazine, 2009, 16(3): 81–94
Vanderborght B, Albu-Schaeffer A, Bicchi A, et al. Variable impedance actuators: A review. Robotics and Autonomous Systems, 2013, 61(12): 1601–1614
Tagliamonte N L, Sergi F, Accoto D, et al. Double actuation architectures for rendering variable impedance in compliant robots: A review. Mechatronics, 2012, 22(8): 1187–1203
Wolf S, Grioli G, Eiberger O, et al. Variable stiffness actuators: Review on design and components. IEEE/ASME Transactions on Mechatronics, 2016, 21(5): 2418–2430
Pratt G A, Williamson M M. Series elastic actuators. In: Proceedings of International Conference on Intelligent Robots and Systems. Human Robot Interaction and Cooperative Robots. Pittsburgh: IEEE, 1995, 399
Wolf S, Eiberger O, Hirzinger G. The DLR FSJ: Energy based design of a variable stiffness joint. In: Proceedings of IEEE International Conference on Robotics and Automation. Shanghai: IEEE, 2011, 5082–5089
Jafari A, Tsagarakis N, Caldwell D. Energy efficient actuators with adjustable stiffness: A review on AwAS, AwAS-II and CompACT VSA changing stiffness based on lever mechanism. Industrial Robot, 2015, 42(3): 242–251
Yigit C B, Bayraktar E, Boyraz P. Low-cost variable stiffness joint design using translational variable radius pulleys. Mechanism and Machine Theory, 2018, 130: 203–219
Edsinger A L. Robot manipulation in human environments. Dissertation for the Doctoral Degree. Boston: Massachusetts Institute of Technology, 2007, 102–109
Morita T, Iwata H, Sugano S. Development of human symbiotic robot: WENDY. In: Proceedings of IEEE International Conference on Robotics and Automation. Detroit: IEEE, 1999, 3183–3188
Tsagarakis N G, Li Z, Saglia J. The design of the lower body of the compliant humanoid robot ‘cCub’. In: Proceedings of IEEE International Conference on Robotics and Automation. Shanghai: IEEE, 2011, 2035–2040
Malosio M, Spagnuolo G, Prini A, et al. Principle of operation of RotWWC-VSA, a multi-turn rotational variable stiffness actuator. Mechanism and Machine Theory, 2017, 116: 34–49
Hurst J W, Chestnutt J E, Rizzi A A. The actuator with mechanically adjustable series compliance. IEEE Transactions on Robotics, 2010, 26(4): 597–606
Eiberger O, Haddadin S, Weis M. On joint design with intrinsic variable compliance: Derivation of the DLR QA-Joint. In: Proceedings of IEEE International Conference on Robotics and Automation. Anchorage: IEEE, 2010, 1687–1694
Friedl W, Höppner H, Petit F. Wrist and forearm rotation of the DLR Hand Arm System: Mechanical design, shape analysis and experimental validation. In: Proceedings of International Conference on Intelligent Robots and Systems. San Francisco: IEEE, 2011, 1836–1842
Wolf S, Hirzinger G. A new variable stiffness design: Matching requirements of the next robot generation. In: Proceedings of IEEE International Conference on Robotics and Automation. Pasadena: IEEE, 2008, 1741–1746
Jafari A, Tsagarakis N G, Sardellitti I, et al. A new actuator with adjustable stiffness based on a variable ratio lever mechanism. IEEE/ASME Transactions on Mechatronics, 2014, 19(1): 55–63
Kim B S, Song J B. Design and control of a variable stiffness actuator based on adjustable moment arm. IEEE Transactions on Robotics, 2015, 28(5): 1145–1151
Groothuis S S, Rusticelli G, Zucchelli A, et al. The variable stiffness actuator vsaUT-II: Mechanical design, modeling, and identification. IEEE/ASME Transactions on Mechatronics, 2014, 19(2): 589–597
Van Ham R, Vanderborght B, Van Damme M, et al. MACCEPA, the mechanically adjustable compliance and controllable equilibrium position actuator: Design and implementation in a biped robot. Robotics and Autonomous Systems, 2007, 55(10): 761–768
Vanderborght B, Tsagarakis N G, Semini C, et al. MACCEPA 2.0: Adjustable compliant actuator with stiffening characteristic for energy efficient hopping. In: Proceedings of International Conference on Robotics and Automation. Kobe: IEEE, 2009, 544–549
Fang L, Wang Y. Study on the stiffness property of a variable stiffness joint using a leaf spring. Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science, 2018, 1989–1996: 203–210
Bi S S, Liu C, Zhao H Z, et al. Design and analysis of a novel variable stiffness actuator based on parallel-assembled-folded serial leaf springs. Advanced Robotics, 2017, 31(18): 990–1001
Liu L, Leonhardt S, Misgeld B J E. Design and control of a mechanical rotary variable impedance actuator. Mechatronics, 2016, 39: 226–236
Wang W, Fu X, Li Y, et al. Design of variable stiffness actuator based on modified gear-rack mechanism. Journal of Mechanisms and Robotics, 2016, 8(6): 061008
Choi J, Hong S, Lee W, et al. A robot joint with variable stiffness using leaf springs. IEEE Transactions on Robotics, 2011, 27(2): 229–238
Tao Y, Wang T, Wang Y, et al. Design and modeling of a new variable stiffness robot joint. In: Proceedings of 2014 International Conference on Multisensor Fusion and Information Integration for Intelligent Systems (MFI). Beijing: IEEE, 2015
Liu Y, Liu X, Yuan Z, et al. Design and analysis of spring parallel variable stiffness actuator based on antagonistic principle. Mechanism and Machine Theory, 2019, 140: 44–58
Shadmehr R, Arbib M A. A mathematical analysis of the force-stiffness characteristics of muscles in control of a single joint system. Biological Cybernetics, 1992, 66(6): 463–477
Chang H, Kim S J, Kim J. Feedforward motion control with a variable stiffness actuator inspired by muscle cross-bridge kinematics. IEEE Transactions on Robotics, 2019, 35(3): 747–760
Mata A S, Torras A B, Carrillo J A C. Fundamentals of Machine Theory and Mechanisms. Cham: Springer, 2016
Acknowledgements
The authors express their gratitude to the referees for carefully reading the paper and providing constructive comments and detailed suggestions for improvement. The authors are also thankful to postgraduate student Qiang Cheng for his support during the writing of the paper. This study was supported by the National Key R&D Program of China (Grant No. 2018YFB1304600), the National Natural Science Foundation of China (Grant Nos. 51975566 and 61821005), and the CAS Interdisciplinary Innovation Team (Grant No. JCTD-2018-11).
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Liu, Y., Wang, D., Yang, S. et al. Design and experimental study of a passive power-source-free stiffness-self-adjustable mechanism. Front. Mech. Eng. 16, 32–45 (2021). https://doi.org/10.1007/s11465-020-0604-4
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DOI: https://doi.org/10.1007/s11465-020-0604-4