Design and Evaluation of a Digital Closed-Loop Controller for the Regulation of Muscle Force by Recruitment Modulation

In principle, orthoses employing electrically stimulated muscles can be improved by the incorporation of closed-loop control systems to regulate muscle output. One obstacle to attaining acceptable closed-loop control systems is the muscle recruitment characteristic, a memoryless, nonlinear, time-varying relationship between the recruitment modulation stimulus parameter (pulsewidth or amplitude) and the muscle force.