Abstract:
Real-world function electrical stimulation (FES) encounters nonlinear effects of fatigue and
time delay that cause the FES controller to underperform and sometimes fail. Nonlinearities
degrade the muscle performance and change the system, but the FES controller cannot be
re-tuned once its parameters are set. System representation using an observer enables the
patient’s knee extension to be represented in a numerical computation algorithm and can
be run or executed in an embedded system. This allows tuning of the closed-loop controller
to be made to the imitated system. The formation of an observer requires parameters to be
collected through feature extraction process. The transformation of these collected
parameters to suitable parameters for the observer formation can be eased with the
establishment of a control law made of equations and rules and finally represented in a look- up table. This paper investigates the feasibility of using the second-order system response to
formulate controller setting and observer formation. MATLAB/Simulink software is used to
study, and the simulation results are used to establish the formulation of the system for an
observer formation representing the knee extension model.
