Model Free Control for muscular force by Functional Electrical Stimulation using pulse width modulation

Functional Electrical Stimulation (FES) is a useful technique for restoring functions for patients with neurological disorders. Muscle activities can be artificially driven through delivery of electrical pulses to skeletal muscles. Typically, muscles are activated by using constant stimulation train with a fixed parameters (amplitude, frequency and pulse width). In addition, the FES systems do not adapt the parameters stimulation to obtain a desired force response during the rehabilitation session. The purpose of this study is to investigate a real-time FES system for adapting automatically the stimulation parameters (stimulation pulse width) to track a desired force. The Model Free Control (MFC) strategy is adopted to compute the pulse width in the stimulation pattern. This strategy is tested with many muscular force references to show their promising control performances.