Piezo tahrikli dokunmatik bir ekranda görüntülenen sanal tümseklerin dokunsal algısı

This thesis aims to design a piezo-actuated touch screen for displaying vibrotactile haptic feedback. We have designed a touch screen to display haptic bumps to a user via four rectangular piezo patches attached to its surface. Using a finite element (FE) model, the dimensions of the screen and the appropriate boundary conditions are determined carefully based on the range of vibration frequencies detectable by a human finger. Then, the optimum configuration (location and orientation) for the piezo patches is determined such that the vibration amplitude of the screen is maximized for a unit voltage applied to each piezo patch. Our FE analysis shows that the best output is obtained when the piezo actuators are placed close to the boundaries and not the free edges. In order to validate the results obtained through the FE model, an experimental modal analysis of the glass plate is also performed using a laser Doppler vibrometer (LDV). Following the design and characterization of the plate, we have investigated the effect of displaying haptic bumps through the plate on human perception of roughness by conducting psychophysical experiments with 10 subjects. To generate the desired haptic bumps displayed to the subjects, the high frequency vibrations of the plate at its first resonance frequency is modulated with desired low frequency unipolar pulse waves in different shape (sinusoidal, square, sawtooth), peak amplitude, duty cycle, and spatial frequency. The subjects are asked to rate their tactile perception of 81 different haptic bumps on a Likert scale of 1-7 using the adjectives of smooth-rough and flat-bumpy. The results of the user study show that the perceived roughness increases with increasing peak amplitude, duty cycle, and spatial frequency. The subjects perceived the square wave as the roughest while the sawtooth was perceived as the smoothest among 3 waveforms. It is also observed that there is a close relation between the root mean square (RMS) values of the signals and roughness perception. Perception of roughness increases as the RMS values of the signals increases.