Active vibration control in human forearm model using paired piezoelectric sensor and actuator

Abstract

An active vibration control system to monitor and suppress the human forearm tremor is proposed in this article. The forearm is modelled as a uniform flexible continuous beam supported by a pin joint and a rotational spring at one end, whereas the other end is free. The beam is covered with a layer of piezoelectric sensor on its top surface and a layer of piezoelectric actuator on its bottom surface to form a control system, through which a closed-loop active control paradigm is implemented for tremor suppression. The governing equation of motion is derived using the Hamilton principle as well as the Galerkin procedure, leading to a second-order ordinary differential equation in time. The vibration response of the structure to an external harmonic excitation, analogous to tremor, is obtained analytically, enabling parametric study of the control system for tremor reduction. Using the obtained analytical expression, the effects of various parameters such as the control gain, the piezoelectric coefficient and the dielectric constant on the vibration response are studied. The results indicated that the proposed active vibration control system is an effective tool for active vibration control. Increasing the control gain of the control system as well as the magnitude of the piezoelectric constant decreased the amplitude of vibration, whereas the dielectric constant of the piezoelectric material did not show to have a significant effect on the beam vibration. The obtained results will pave the way for further experimental exploration to take and fabricate the most appropriate piezoelectric material and to design an effective active vibration control system for tremor suppression in people with Parkinson’s disease.