Studies on a Robotic Device that Minimizes End-Point Vibrations for Parkinson Tremor

Abstract

Parkinson tremor is a neuromotor condition that produces involuntary oscillation movements in some parts of the body, especially at the upper limbs. This disease affects more than 10 million people in the world and around 150 thousand people in Turkey, according to the report by the World Health Organization. This work focuses on simulating a robotic device in the shape of a glass for drinking liquids, which is an ordinary action for a normal person but can be very difficult for a Parkinson patient. This robotic device can minimize end-point vibrations when it is manipulated by people suffering from tremor. The work makes use of real-time data gathered from a patient, presents studies to characterize the main frequency of the tremor, and employs this information for designing an active control method. The proposed control method is based on the inverse dynamics of the vibrating system to damp the tremor's first vibrational frequency component. The work consists of three stages: Data acquisition, characterization and simulation of the control action. The first stage involves acceleration sensors based movement analysis to identify the frequencies and the behavior of the tremor; followed by a signal processing approach is developed using the fast Fourier transform. The studies indicate that the tremor could be represented by a harmonic signal in which the first frequency mode is the most representative. This assumption allows for simplifying our control strategy: Inverse dynamics in an open-loop control along with proportional-derivative closed-loop controller are performed. The experimental data acquisition, signal analysis and control simulations were realized via Matlab/Simulink. The results illustrate the system performance validating our assumptions and the success of the control method we propose, which could lead to the design of a device to minimize vibrations at the end-point of the glass.