Improving reaching with functional electrical stimulation by incorporating stiffness modulation
Objective. Intracortical recordings have now been combined with functional electrical stimulation
(FES) of arm/hand muscles to demonstrate restoration of upper-limb function after spinal cord
injury. However, for each desired limb position decoded from the brain, there are multiple
combinations of muscle stimulation levels that can produce that position. The objective of this
simulation study is to explore how modulating the amount of coactivation of antagonist muscles
during FES can impact reaching performance and energy usage. Stiffening the limb by cocontracting
antagonist muscles makes the limb more resistant to perturbation. Minimizing cocontraction saves
energy and reduces fatigue. Approach. Prior demonstrations of reaching via FES used a fixed
empirically-derived lookup table for each joint that defined the muscle stimulation levels that
would position the limb at the desired joint angle decoded from the brain at each timestep. This
study expands on that pr...