Prediction of Individual Finger Forces Based on Decoded Motoneuron Activities

Torque Estimation Using Neural Drive for a Concentric Contraction

“…The collected HDsEMG data was filtered between 20 Hz and 400 Hz using a zero-phase digital 6th order Butterworth bandpass filter. To reduce 60 Hz noise, a zero-phase 2nd order notch filter with half power frequencies set at 59Hz and 61 HZ was utilized as well [6].…”

“…We chose to adapt an existing convolutive BSS algorithm developed by F. Negro et al [5]. This algorithm has been validated and implemented in multiple studies [5], [6], [11], [12]. Briefly, the decomposition steps implemented in this algorithm are (1) signal whitening and extension (convolutive sphering), (2) deconvolution by FastICA, and (3) identification of neural activity by peak detection and K-Means classification [13].…”

“…For both rate coding and kernel smoothing, all the discharge events from the contraction were first pooled into a composite spike train. Generating the composite spike train has been previously implemented for neural-drive and muscle force output estimation methods [6]. After generating the composite spike train, any discharges that occurred within ± 3 ms of each other were considered to be common [15].…”

“…After generating the composite spike train, any discharges that occurred within ± 3 ms of each other were considered to be common [15]. The rate coding method was implemented by computing the instantaneous firing rate of the composite spike train every 50 ms with a 350 ms window [6]. The instantaneous firing rates were then low-pass filtered with a frequency cutoff of 50 Hz.…”

“…Blind source separation (BSS) techniques have been shown to decompose high-density sEMG (HDsEMG) into motor neuron spike trains [3]- [5]. Additionally, studies have shown that joint output torque is better estimated using these extracted motor neuron spike train than traditional sEMG torque estimation methods [6], [7]. While this approach has been validated during static, low-level muscle contractions, it is still unclear how these methods will perform during dynamic movements.…”