Tremor-Active Controller for Dielectric Elastomer-Based Pathological Tremor Suppression

Pathological tremor causes involuntary motion that impairs a person's ability to function in daily activities. Typical treatments are not always effective and have inherent risks and side effects. Since tremor manifests itself as a mechanical motion, it may be possible to suppress tremor mechanically. Tremor suppression with dielectric elastomer actuators may improve clinical implementation potential by increasing human body compatibility. Dielectric elastomers are relatively soft and compliant, enabling low-profile implementations that conform to the human joint. However, dielectric elastomers also have relatively low actuation levels. This article develops a control approach that only actuates to suppress tremor, allowing the human motor system to overcome the passive actuator dynamics. This control approach leverages the low mechanical impedance of dielectric elastomers to compensate for their low actuation levels. The controller employs a zero-phase filter to estimate the tremor signal and an adaptive feedback gain to minimize active influence on the voluntary motion. Numerical simulations demonstrate excellent and robust tremor suppression. These theoretical results motivate future applied research toward dielectric elastomer-based tremor suppression. The proposed system can establish a path toward significant improvements in user comfort, device profile, and scalability-all factors that currently prohibit the clinical use of mechanical tremor suppression.