Article

The potential efficacy of total body center of mass (COM) acceleration for
feedback control of standing balance by functional neuromuscular stimulation
(FNS) following spinal cord injury (SCI) was investigated. COM acceleration may
be a viable alternative to conventional joint kinematics because of its rapid
responsiveness, focal representation of COM dynamics, and ease of measurement. A
computational procedure was developed using an anatomically realistic,
three-dimensional, bipedal biomechanical model to determine optimal patterns of
muscle excitations to produce targeted effects upon COM acceleration from erect
stance. The procedure was verified with electromyographic data collected from
standing nondisabled subjects undergoing systematic perturbations. Using 16
muscle groups targeted by existing implantable neuroprostheses, we generated data
to train an artificial neural network (ANN)-based controller in simulation.
During forward simulations, proportional feedback of COM acceleration drove the
ANN to produce muscle excitation patterns countering the effects of applied
perturbations. Feedback gains were optimized to minimize upper-limb (UL) loading
required to stabilize against disturbances. Compared with the clinical case of
maximum constant excitation, the controller reduced UL loading by 43% in
resisting external perturbations and by 51% during simulated one-arm reaching.
Future work includes performance assessment against expected measurement errors
and development of user-specific control systems.

Langue : ANGLAIS