History of Robotics Research and Development of Japan2013LocomotionIdentifying the Building Blocks of a Human Walking based on the EMG ratio of Agonist-antagonist Muscle Pairs

Hiroaki HiraiOsaka University
Taiki IimuraOsaka University (currently Hitachi, Ltd.)
Keita InoueOsaka University (currently Panasonic Corp.)
Fumio MiyazakiOsaka University
The problem of motor redundancy is well known as Bernstein's problem, named after the scientist who first posed the knotty problem in the early 1930s. At present, it is still a mystery how the central nervous system (CNS) solves the ill-posed problem of motor control. We recently made a discovery that links with influential hypotheses that the CNS may produce movements by combining units of motor output. This paper introduces the key concept we call the ``A-A ratio," which is the EMG ratio of agonist-antagonist muscle pairs. The statistical analysis based on the A-A ratio specifies that (1) human lower limb movement during walking is explained as the superposition of a few modular units, and that (2) the decomposed modules encode the kinematic information of body movement. The results also clarifies that various hypotheses, such as the muscle synergy hypothesis, the population vector hypothesis, and the convergent force fields hypothesis, are different interpretations of a common equation derived from our analysis. The concept of the A-A ratio provides a beneficial suggestion to many studies on muscle-synergy extraction and gives an important clue to solving Bernstein's problem of redundant degrees of freedom. (27th (2013) Best Paper Award) 27th RSJ Best Paper Award in 2013. IEEE Robotics and Automation Society Japan Chapter Young Award (IROS2011) in 2011.
Motion measurement during treadmill walking


Correspondence papers

Hiroaki Hirai, Taiki Iimura, Keita Inoue, and Fumio Miyazaki:Identifying the Building Blocks of a Human Walking based on the EMG Ratio of Agonist-antagonist Muscle Pairs

Journal of Robotics Society of Japan, Vol. 30, No. 5, pp. 524-533, 2012 (in Japanese).

Hiroaki Hirai, Kazuhiro Matsui, Taiki Iimura, Keigo Mitsumori, and Fumio Miyazaki:Modular Control of Limb Kinematics during Human Walking

Proceedings of 2010 3rd IEEE RAS and EMBS International Conference on Biomedical Robotics and Biomechatronics (BioRob2010), pp. 716-721, 2010.

Taiki Iimura, Keita Inoue, Hang T. T. Pham, Hiroaki Hirai, and Fumio Miyazaki:A Preliminary Experiment for Transferring Human Motion to a Musculoskeletal Robot – Decomposition of Human Running based on Muscular Coordination

Proceedings of 2011 IEEE/RSJ International Conference on Intelligent Robots and Systems (IROS2011), pp. 4496-4501, 2011.

Fumio Miyazaki, Hiroaki Hirai, Syohei Kawagoe, Kazuhiro Matsui, and Takayuki Nakano:Muscle Synergy Analysis Method, Muscle Synergy Analyzer, and Muscle Synergy Interface

WO/2011/030781, 17.03.2011.

Related papers

[1] N. A. Bernstein: The co-ordination and regulation of movements. Pergamon, 1967.

[2] G. Cappellini, Y. P. Ivanenko, R. E. Poppele, and F. Lacquaniti, “Motor Patterns in Human Walking and Running,” Journal of Neurophysiology, vol. 95, no. 6, pp. 3426-3437, 2006.

[3] A. P. Georgopoulos, J. F. Kalaska, R. Caminiti, and J. T. Massey: “On the relations between the direction of two-dimensional arm movements and cell discharge in primate motor cortex,” J. Neuroscience, vol. 2, no.11, pp. 1527-1537, 1982.

[4] E. Bizzi, F. A. Mussa-Ivaldi, and S. Giszter: “Computations underlying the execution of movement: a biological perspective,” Science, vol. 253, pp. 287-291, 1991.

[5] H. Pham, Y. Ariga, K. Tominaga, T. Oku, K. Nakayama, M. Uemura, H. Hirai, and F. Miyazaki, “Extraction and implementation of muscle synergies in neuro-mechanical control of upper limb movement,” Advanced Robotics, vol. 28, no. 11, pp. 745-757, 2013.

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