A Biorealistic Computational Model Unfolds Human-Like Compliant Properties for Control of Hand Prosthesis

Abstract

System overview of a virtual prosthetic hand with a biorealistic neuromorphic reflex controller, whose inputs are α motor command, γs and γd commands. B.Block diagram of the integrated virtual hand system. It consists of a tendon-driven virtual hand, a pair of antagonistic muscles with the biorealistic controller and a sensory feedback system. Force perturbations can be applied at the fingertip, or at the tendon of flexor/extensor muscles in perturbation experiments. C. Simulation results unveil that the virtual hand has acquired human-like ability of compliant control as follows. (1) The virtual hand can switch control modes between position and force naturally according to external loads. (2) The variability of fingertip force increases with the mean force in proportion (R 2 =0.99, p=0.0000). It implies the capability for fine force manipulation with low levels of muscle activation. (3) The virtual hand can achieve stable control of finger equilibrium positions and reflex regulation of muscle stiffness via Ia afferent, which enhances fingertip and muscle stiffness. (4) Muscle stiffness can be modulated by α command linearly and adaptively adjusted with object stiffness for a given background activation. The length-tension curve and reflex compensation underscore the neuromechanical mechanism of stiffness adaptation.

A hybrid sensory feedback system for thermal nociceptive warning and protection in prosthetic hand

“…Figure 4 depicted the feasibility of adjusting reflexive alpha motor commands upon detection of nociceptive temperature. Results revealed that these alpha motor command adjustments could generate well-behaved muscle forces, which were consistent with the previous research ( Niu et al, 2021 ; Zhang Z. et al, 2022 ). This withdrawal reflex originated in the spinal cord and was a demonstration of the short-latency spinal reflex, which was a subconscious action to unpredictable perturbation ( Andersen, 2007 ; Zangrandi et al, 2021 ).…”

“…In this study, normalized sEMG was used to represent the alpha motor command, with the sEMG normalized to 0 and 1 when the subject was resting and exerting maximum voluntary contraction force, respectively. More detailed information was published in previous research ( Xie et al, 2022 ; Zhang et al, 2022b , Zhang Z. et al, 2022c ).…”

A bioinspired neuromuscular system enabled by flexible electro-optical N2200 nanowire synaptic transistor

“…Designing electronic prosthetics with a greater biological realism is essential for improving their compatibility with the sensory and motor nervous systems [55]. Thus, a deeper understanding of human neuromuscular reflex replicas is required, including emerging qualities such as human-like compliance, force and position control, as well as adaptive stiffness [56]. These qualities will enhance the compatibility of neuroprosthetics with the human body.…”

Non-linear adaptive control inspired by neuromuscular systems

“…In artificial systems, the optimalities will likely not fully overlap with those found in the biological system (Dideriksen et al 2012). Finally, the approach presented here may have useful implications for neuroprosthetics (Unal et al 2018, Lan et al 2023, Zhang et al 2022.…”