Synthesis of Optimal Electrical Stimulation Patterns for Functional Motion Restoration Applied to Spinal Cord Injured Patients

Mourad Benoussaad (1, 2) , Philippe Poignet (2) , Mitsuhiro Hayashibe (2) , Christine Azevedo Coste (2) , Charles Fattal (3) , David Guiraud (2)

1 LGP - Laboratoire Génie de Production
2 DEMAR - Artificial movement and gait restoration
3 PROPARA - Centre Mutualiste de Réeducation Neurologique Propara

We investigated the synthesis of electrical stimulation patterns for functional movement restoration in human paralyzed limbs. We considered the knee joint system, co-activated by the stimulated quadriceps and hamstring muscles. This synthesis is based on optimized functional electrical stimulation (FES) patterns to minimize muscular energy consumption and movement efficiency criteria. This two-part work includes a multi-scale physiological muscle model, based on Huxley’s formulation. In the simulation, three synthesis strategies were investigated and compared in terms of muscular energy consumption and co-contraction levels. In the experimental validation, the synthesized FES patterns were carried out on the quadriceps-knee joint system of four complete spinal cord injured subjects. Surface stimulation was applied to all subjects, except for one FES-implanted subject who received neural stimulation. In each experimental validation, the model was adapted to the subject through a parameter identification procedure. Simulation results were successful and showed high co-contraction levels when reference trajectories were tracked. Experimental validation results were encouraging, as the desired and measured trajectories showed good agreement, with an 8.4 % rms error in a subject without substantial time-varying behavior. We updated the maximal isometric force in the model to account for time-varying behavior, which improved the average rms errors from 31.4 to 13.9 % for all subjects.

Mots clés: Rehabilitation; Optimization techniques; FES synthesis; Physiological musculoskeletal model; FES; Spinal Cord Injury; Functional electrical stimulation

Domaines: Automatique / Robotique; Biotechnologie

Mourad Benoussaad, Philippe Poignet, Mitsuhiro Hayashibe, Christine Azevedo Coste, Charles Fattal, et al.. Synthesis of Optimal Electrical Stimulation Patterns for Functional Motion Restoration Applied to Spinal Cord Injured Patients. Medical and Biological Engineering and Computing, 2015, 53 (3), pp.227-240. ⟨10.1007/s11517-014-1227-x⟩. ⟨lirmm-01235810⟩