Wrist torque estimation during simultaneous and continuously changing movements: surface vs. untargeted intramuscular EMG

Abstract

Kamavuako EN, Scheme EJ, Englehart KB. Wrist torque estimation during simultaneous and continuously changing movements: surface vs. untargeted intramuscular EMG. J Neurophysiol 109: 2658-2665, 2013. First published March 20, 2013 doi:10.1152/jn.00086.2013In this paper, the predictive capability of surface and untargeted intramuscular electromyography (EMG) was compared with respect to wrist-joint torque to quantify which type of measurement better represents joint torque during multiple degrees-of-freedom (DoF) movements for possible application in prosthetic control. Ten able-bodied subjects participated in the study. Surface and intramuscular EMG was recorded concurrently from the right forearm. The subjects were instructed to track continuous contraction profiles using single and combined DoF in two trials. The association between torque and EMG was assessed using an artificial neural network. Results showed a significant difference between the two types of EMG (P Ͻ 0.007) for all performance metrics: coefficient of determination (R 2 ), Pearson correlation coefficient (PCC), and root mean square error (RMSE). The performance of surface EMG (R 2 ϭ 0.93 Ϯ 0.03; PCC ϭ 0.98 Ϯ 0.01; RMSE ϭ 8.7 Ϯ 2.1%) was found to be superior compared with intramuscular EMG (R 2 ϭ 0.80 Ϯ 0.07; PCC ϭ 0.93 Ϯ 0.03; RMSE ϭ 14.5 Ϯ 2.9%). The higher values of PCC compared with R 2 indicate that both methods are able to track the torque profile well but have some trouble (particularly intramuscular EMG) in estimating the exact amplitude. The possible cause for the difference, thus the low performance of intramuscular EMG, may be attributed to the very high selectivity of the recordings used in this study. simultaneous movement; intramuscular EMG; surface electromyography; dynamic movement; torque and force estimation

On the usability of intramuscular EMG for prosthetic control: A Fitts’ Law approach

“…The predictive capability of intramuscular EMG with respect to force has also been shown during single (Kamavuako et al, 2012b) and simultaneous (Kamavuako et al, 2012a) DoF. Recently a comparison between surface and intramuscular using simultaneous and continuously changing torque has been reported (Kamavuako et al, 2013b). It was indicated that both methods were able to track the torque profile well, but had some trouble (particularly intramuscular EMG) in estimating the exact amplitude.…”

Evaluation of Linear Regression Simultaneous Myoelectric Control Using Intramuscular EMG

“…Such approaches have included conventional myoelectric control methods [8, 9] and nonlinear regression methods [10]. Notably, intramuscular EMG obtained from Implantable Myoelectric Sensors (IMES ® ) in the forearm were used to simultaneously control prosthetic wrist rotation and a 2-DOF hand [11, 12].…”

Real-time simultaneous and proportional myoelectric control using intramuscular EMG

“…Most recent studies on intramuscular EMG control have instead focused on the machine-learning algorithms that are also being pursued for surface EMG (Kamavuako et al, 2012, Kamavuako et al, 2013b, Smith and Hargrove, 2013). However, the few studies of parallel dual-site control have been promising.…”