Emulation of muscle tone of upper limb spasticity and rigidity

Abstract

Stretching the elbow of patients with upper limb disorder elicits diverse muscle tone responses, for instance, in an increased, uniform or jerky manner. This work addresses the emulation of muscle tone of the symptoms of spasticity, lead-pipe rigidity and cogwheel rigidity in the upper limb. A hybrid actuation strategy capable of emulating dynamic muscle tone has been proposed. In such strategy, a Magneto-Rheological brake is used to produce the resistance for a constant stiffness, and supported by a DC servo motor to assist the time delay of the fluid particle settling rate of the magneto-rheological fluid. The outcome is a consistent replication of the motion characteristics where the resistance torque emulated at the elbow joint is in close resemblance with the simulated data of upper limb spasticity and rigidity.