FES based tremor suppression using repetitive control

Abstract

Tremor is a neurological condition present in half of all multiple sclerosis and Parkinson cases, resulting in involuntary, debilitating movement oscillations. Functional electrical stimulation (FES) can be used to suppress tremor, but current approaches using classical control methods have shown significant limitations. This paper establishes the feasibility of using repetitive control (RC), giving rise to the first FES control structure that embeds learning from experience for the purpose of suppressing tremor. The paradigm is applied to suppress tremor at the wrist via FES regulated co-contraction of wrist extensors/flexors. Experimental evaluation is performed using a validated wrist-rig and results are compared against classical feedback control design to establish the efficacy of the approach.

Controlling a motorized orthosis to follow elbow volitional movement: tests with individuals with pathological tremor

“…A number of systems designed for the suppression of upper limb tremor employed suppressive technologies such as viscous and magnetic fluids, magnetic particle brakes, pneumatic actuators and DC motors [16–26] while others employed Functional Electrical Stimulation (FES) [4, 27–35]. Of the above systems, several were demonstrated with individuals with tremor [17–20, 27–32] resulting in ~ 20–88% tremor attenuation levels, although attenuation levels were not computed consistently across the studies and should therefore be considered cautiously.…”

“…Of the above systems, several were demonstrated with individuals with tremor [17–20, 27–32] resulting in ~ 20–88% tremor attenuation levels, although attenuation levels were not computed consistently across the studies and should therefore be considered cautiously. The remaining systems focused on design or experimental testing whereby the human motion (tremor and voluntary) was simulated physically or in software [4, 16, 22–26, 33–35]. Limitations of non FES technologies tend to be related to size and weight whereas the main limitations associated with FES are muscle fatigue, stimulation discomfort and difficulty in accessing specific muscles through surface electrodes.…”