Fig. 1: Neuroprosthesis.
From: Continuous neural control of a bionic limb restores biomimetic gait after amputation
a, Schematic diagram showing the neuroprosthetic interface and a bionic leg fully driven by the human nervous system. Enhancing residual muscle afferents boosted the primary feedback modality for motor gait control and adaptation. Through continuous neural control of the bionic leg, individuals could effectively fine-tune their residual motor control to achieve a biomimetic bionic gait. Mechanical information was conveyed to the nervous system through pressure gradients within the prosthetic socket during ground contact, which mechanically stimulated residual tissues. Such an additional afferent signaling apparatus may provide perceptual experiences for sensorimotor adaptation. b, The neuroprosthetic interface consists of the AMI and skin-mounted EMG flexible electrodes. The AMI is shown to augment agonist–antagonist afferent signaling compared with the non-AMI, CTL cohort (bars, mean; error bars, s.e.m.; n = 7 per cohort, two-sided unpaired t-test, ***P = 7.7 × 10−7). Note that four of the seven CTL muscle afferents increased (non-biomimetic) when working as agonists, resulting in negative values for agonist–antagonist muscle afferents. c, Components of the autonomous neuroprosthesis are shown. The EMG signals from the TA and GAS were used to continuously control the bionic ankle throughout each phase of gait. To create an upper torque bound for the EMG controller, maximal prosthetic joint torque for each measured joint state was defined using literature values for maximal muscle force–length and force–velocity characteristics at each ankle position and velocity43,44. In addition, measured joint state was used to estimate the torque contribution from passive biological structures such as ligaments and joint capsules. Here, no intrinsic gait control techniques were used to drive the bionic leg, such as state machine and pattern recognition algorithms. Extended Data Figs. 1 and 2, respectively, show the neuroprosthetic system and residual muscle neuromechanics in more detail.
