Mechanism of Improving Joint Motion Performance of Variable Stiffness Robot Based on EMG Signal

doi:10.3901/JME.2025.23.027

Abstract

Abstract: To explore the challenges of robot compliance and environmental adaptability in human-robot collaborative environments, a method is proposed for driving antagonistic flexible variable stiffness robotic joints based on surface electromyographic (sEMG) signals. This method employs an elbow joint stiffness estimation strategy derived from sEMG signals and an improved Hill muscle model to calculate joint torques and angles, thereby capturing the stiffness variation patterns of the human musculoskeletal system during motion. A motion angle and joint stiffness estimation approach integrating sEMG signals with neural networks is introduced to achieve decoupled control of stiffness and position in antagonistic variable stiffness joints. A physiological-physical control scheme is designed to emulate the coordination patterns of position and stiffness in the human elbow joint, aiming to enhance the motion capabilities of variable stiffness robotic joints. Finally, dart-throwing experiments demonstrate that incorporating the stiffness regulation principles of the human musculoskeletal system can improve the motion performance of variable stiffness robotic joints in task execution. This research provides new insights and technical support for the application of robots in complex human-robot interaction environments.

Key words: variable stiffness, robot joint, EMG signal, hill muscle model, athletic ability

CLC Number:

TP242

ZHANG Ming, GUO Huaichao, WEN Jianming, SUN Feng, SUN Xingwei, FANG Lijin, OKA Koichi. Mechanism of Improving Joint Motion Performance of Variable Stiffness Robot Based on EMG Signal[J]. Journal of Mechanical Engineering, 2025, 61(23): 27-40.

References

[1] ZHENG B,XU P,GUO Z,et al. Origami-inspired variable stiffness actuator for safe human-robot interaction[J]. Journal of Mechanisms and Robotics,2024,16(4):041009.
[2] ZHONG H,LI X,GAO L,et al. Toward safe human-robot interaction:A fast-response admittance control method for series elastic actuator[J]. IEEE Transactions on Automation Science and Engineering,2021,19(2):919-932.
[3] ZHANG M,FANG L J,SUN F,et al. Mechanical analysis and controller design of flexible joints[J]. Journal of Mechanical Engineering,2019(5):89-96.
[4] RHEE I,KANG G,MOON S J,et al. Hybrid impedance and admittance control of robot manipulator with unknown environment[J]. Intelligent Service Robotics,2023,16(1):49-60.
[5] OTT C,MUKHERJEE R,NAKAMURA Y. A hybrid system framework for unified impedance and admittance control[J]. Journal of Intelligent & Robotic Systems,2015,78:359-375.
[6] DA SILVA L D L,PEREIRA T F,LEITHARDT V R Q,et al. Hybrid impedance-admittance control for upper limb exoskeleton using electromyography[J]. Applied Sciences,2020,10(20):7146.
[7] SHARKAWY A N,KOUSTOUMPARDIS P N. Human-robot interaction:A review and analysis on variable admittance control,safety,and perspectives[J]. Machines,2022,10(7):591.
[8] WANG W,ZHAO Y,LI Y. Design and dynamic modeling of variable stiffness joint actuator based on archimedes spiral[J]. IEEE Access,2018,6:43798-43807.
[9] MA L,LENG Y,JIANG W. Design an underactuated soft exoskeleton to sequentiallyprovide knee extension and ankle plantarflexion assistance[J]. IEEE Robotics and Automation Letters,2022,7(1):271-278.
[10] WANG C,SHENG B,LI Z,et al. A lightweight series elastic actuator with variable stiffness:Design,modeling,and evaluation[J]. IEEE/ASME Transactions on Mechatronics,2023,28(6):3110-3119.
[11] DEBOER B,HOSSEINI A,ROSSA C. A discrete non-linear series elastic actuator for active ankle-foot orthoses[J]. IEEE Robotics and Automation Letters,2022,7(3):6211-6217.
[12] 李守忠,管昀毅,马冲,等. 上肢康复机器人被动变刚度驱动器建模与试验[J]. 机械工程学报,2024,60(3):47-54. Li Shouzhong,GUAN Yunyi,MA Chong,et al. Modeling and test of passive variable stiffness actuator for upper limb rehabilitation robot[J]. Journal of Mechanical Engineering,2024,60(3):47-54.
[13] SUN J,GUO Z,ZHANG Y,et al. A novel design of serial variable stiffness actuator based on an archimedean spiral relocation mechanism[J]. IEEE/ASME Transactions on Mechatronics,2018,23(5):2121-2131.
[14] HOCAOGLU E,PATOGLU V. sEMG-based natural control interface for a variable stiffness transradial hand prosthesis[J]. Frontiers in Neurorobotics,2022,16:789341.
[15] LIU Y,GUO S,HIRATA H. et al. Development of a powered variable-stiffness exoskeleton device for elbow rehabilitation[J]. Biomed Microdevices,2018,20:1-13.
[16] YANG Z,GUO S,SUZUKI K et al. An emg-based biomimetic variable stiffness modulation strategy for bilateral motor skills relearning of upper limb elbow joint rehabilitation[J]. Journal of Bionic Engineering,2023,20:1597-1612.
[17] XU D,WU Q,ZHU Y. Development of a semg-based joint torque estimation strategy using hill-type muscle model and neural network[J]. Journal of Medical and Biological Engineering,2021,41:34-44.
[18] LI Y,GANESH G,JARRASSÉ N,et al. Force,impedance,and trajectory learning for contact tooling and haptic identification[J]. IEEE Transactions on Robotics,2018,34(5):1170-1182.
[19] MAURUS P,MAHDI G,CLUFF T. Increased muscle coactivation is linked with fast feedback control when reaching in unpredictable visual environments[J]. iScience,2024,27(11):111174.
[20] BURDET E,OSU R,FRANLLIN D W,et al. The central nervous system stabilizes unstable dynamics by learning optimal impedance[J]. Nature,2001,414:446-449.
[21] CHAI Y Y,LIU K P,LI C X,et al. A novel method based on long short term memory network and discrete-time zeroing neural algorithm for upper-limb continuous estimation using sEMG signals[J]. Biomedical Signal Processing and Control,2021,67:102416.
[22] TAKAGI A,BURDET E,KOIKE Y. The control of the arm's equilibrium position[J]. Journal of Neurophysiology,2024,131(4):750-756.
[23] SHEN C,PEI Z. STMI:Stiffness estimation method based on sEMG-driven model for elbow joint[J]. IEEE Transactions on Instrumentation and Measurement,2023,72:1-14.
[24] ZHU Y,WU Q,CHEN B,et al. Physical human-robot interaction control of variable stiffness exoskeleton with semg-based torque estimation[J]. IEEE Transactions on Industrial Informatics,2023,19(10):10601-10612.
[25] YANG Z,GUO S. An EMG-based biomimetic variable stiffness modulation strategy for bilateral motor skills relearning of upper limb elbow joint rehabilitation[J]. Bionic. Eng.,2023,20:1597-1612.
[26] HAN J,DING Q,XIONG A,et al. A state-space EMG model for the estimation of continuous joint movements[J]. IEEE Transactions on Industrial Electronics,2015,62(7):4267-4275.
[27] BORZELLI D,BURDE E. Identification of the best strategy to command variable stiffness using electromyographic signals[J]. Journal of Neural Engineering,2020,17(1):016058.1-016058.14.
[28] NÖLLE L V,WOCHNER I,HAMMER M,et al. Using muscle-tendon load limits to assess unphysiological musculoskeletal model deformation and hill-type muscle parameter choice[J]. PloS One,2024,19(11):e0302949.
[29] ROSENDO A,IIDA F. Energy efficient hopping with Hill-type muscle properties on segmented legs[J]. Bioinspiration & Biomimetics,2016,11(3):036002.
[30] ROMAN-LIU D,BARTUZI P. Influence of type of MVC test on electromyography measures of biceps brachii and triceps brachii[J]. International Journal of Occupational Safety and Ergonomics,2018,24(2):200-206.
[31] HAEUFLE D F B,GÜNTHER M,BAYER A,et al. Hill-type muscle model with serial damping and eccentric force-velocity relation[J]. Journal of Biomechanics,2014,47(6):1531-1536.
[32] ZHANG J,LI K,LIU L,et al. A novel elbow joint modeling method based on sEMG[C]//2016 IEEE International Conference on Robotics and Biomimetics (ROBIO). IEEE,2016:307-312.
[33] HU B,TAO H,LU H,et al. An Improved EMG-driven neuromusculoskeletal model for elbow joint muscle torque estimation[J]. Applied Bionics and Biomechanics,2021(1):1985741.
[34] DE OLIVEIRA J,DE SOUZA M A,ASSEF A A,et al. Multi-sensing techniques with ultrasound for musculoskeletal assessment:A review[J]. Sensors,2022,22(23):9232.
[35] 张明,房立金,孙凤,等. 永磁变刚度柔性关节的力学分析与控制器设计[J]. 机械工程学报,2019,55(5):89-96. ZHANG Ming,FANG Lijin,SUN Feng,et al. Mechanical analysis and controller design of permanent magnet flexible joints with variable stiffness[J]. Journal of Mechanical Engineering,2019,55(5):89-96.