MyoPassivity Map: Does Multi-Channel sEMG Correlate with the Energetic Behavior of Upper-Limb Biomechanics During Physical Human-Robot Interaction?

The human arm has an intrinsic capacity to absorb energy during physical human-robot interaction (pHRI), which can be identified as biomechanical excess of passivity (EoP). This can be used as a central factor in the development of passivity-based pHRI controllers securing haptic transparency while guaranteeing pHRI stability. Despite its significance, the real-time estimation of EoP remains an under-investigated topic. For the first time, we investigate the relationship between the EoP and muscle activity of the forearm at the wrist joint while analyz- ing sixteen surface electromyography (sEMG) sensors. The study explores optimal sensor placement for maximizing the correlation between muscle activity and the estimated EoP. Ten subjects participated in this study. The EoP of the wrist was identified through high-frequency perturbations in four directions, and two instructed co-contraction levels. The results uncover a strong correlation between sEMG and EoP. This paper also reports the effect of the direction of pHRI interaction on the EoP of the wrist, with increased energetic passivity in the abduction-adduction direction compared to supination-pronation. Also, the study investigated the effect of the observation duration for sEMG on the sEMG-EoP correlation (short windows would be required for real-time applications). Although the correlation decreases for shorter windows, it remains relatively high, supporting dynamic estimation of EoP in real-time. Additionally, we found that sEMG sensors near the wrist have the highest correlation with EoP for short windows. The findings of this paper indicate that sEMG encodes significant potential for real-time estimation of EoP in the design of next-generation pHRI controllers supporting Manuscript received 16 May 2023; accepted 26 August 2023. Date of publication 8 September 2023; date of current version 19 September 2023. This letter was recommended for publication by Associate Editor T. Hulin and Editor J.-H. Ryu upon evaluation of the reviewers’ comments. This work was supported in part by the US National Science Foundation (NSF) under Grants 2229697, 2208189, and 2121391, in part by NYUAD CAIR under Grant CG010, and in part by GAANN under Grant P200A210062. (Peter Paik and Xingyuan Zhou contributed equally to this work.) (Corresponding author: S. Farokh Atashzar.) This work involved human subjects or animals in its research. Approval of all ethical and experimental procedures and protocols was granted by the Institutional Review Board of the New York University (IRB No. FY2022- 5888) and performed in line with the Declaration of Helsinki. 1Suzanne Oliver is with the Department of Mechanical and Aerospace Engineering, New York University (NYU), New York, NY, 11201 USA (email: sho8511@nyu.edu) 2Peter Paik and Xingyuan Zhou are with the Department of Elec- trical and Computer Engineering, NYU (email: hsp287@nyu.edu, xz3428@nyu.edu) 3S. Farokh Atashzar is with the Departments of Electrical and Computer Engineering, Mechanical and Aerospace Engineering, and Biomedical En- gineering, NYU. Atashzar is also with NYU WIRELESS Center and NYU CUSP (email: f.atashzar@nyu.edu) Digital Object Identifier 10.1109/LRA.2023.3313489 concurrent transparency and stability.