Index finger prosthesis control method according to human intention

Abstract

The paper proposes a control method of an index finger prosthesis by using two electromyographic signals measured on skin surfaces of two muscles (flexor digitorum superficialis and the extensor indicis) in a lower arm. We assume that the mass of the human index finger is sufficiently small for its dynamic effect to be neglected and the initial burst part of electromyographic signal generated by human intention precedes the onset of actual displacement of the index finger. In order to make the control input for the index finger prosthesis, the root mean squaring operation is applied firstly to the measured electromyographic signal, the thresholding operation is secondly utilized to extract the initial burst part, the synergistic signal is thirdly constructed by using the difference between two processed electromyographic signals, and then the desired displacement is derived from the scaled synergistic signal and numerical integration. Physical limits of the utilized actuator such as displacement and speed limits are considered for practical control use. Finally we show the effectiveness of the proposed control method through experimental result.