On-line bio-impedance identification of fingertip skin for enhancement of electrotactile based haptic rendering

In this paper, we focus on developing a new constant-voltage-driver (CVD) based electrotactile display system. The system owns the feature of on-line identifying the bio-impedance parameters of fingertip skin for individual tactile preference tuning and haptic rendering enhancement. The identification method relies on a discrete-time extended least squares (ELS) iterative approach with forgetting factor (FF), which serves as an adaptive law to on-line estimate parameters of the first-order bio-impedance model of fingertip skin when the stimulation current control is performing in z-domain. Experimental results demonstrate the performance of the developed CVD electrotactile display, as well verify the effectiveness of the proposed on-line identification method. That is, it is capable of quickly estimating parameters of the fingertip skin bio-impedance model. The significance of our work is that it will greatly improve the tactile/haptic rendering performance of electrical stimulation (electrotactile) systems and benefits the development of electrotactile based haptic rendering devices and applications.