(A) smart actuator based on electrodynamics and piezoelectric effect for haptic feedback

Abstract

This thesis presents a smart haptic actuator which can increase the degree of realism or immersion in interacting with mobile devices. One of the most dominant factors in developing haptic actuators for mobile devices is the ability to create a variety of vibrotactile sensation in limited size. Haptic actuators allow users to experience the same sensation as if they touch a real object. Therefore, the mobile devices based on the haptic actuator can be a solution for creating the sense of the manipulation on touch screen which are difficult to generate button sensation. Even though many conventional haptic actuators with low power consumption can be easily embedded into mobile devices, the haptic actuator can hardly generate sufficient vibrotactile sensation due to the limited frequency range. Another problem is that it is not easy to create crispy vibrotactile sensation with conventional haptic actuators due to the residual vibration in the actuators. To solve these problems, the smart actuator combined with a sensor and a vibrotactile actuator is proposed. The proposed actuator, which is based on electrodynamics and piezoelectric effects, consists of the two main parts : (1) a closed flux path which is combining fluxes due to a solenoid coil and a permanent magnet and (2) a stroke sensing which measures actuating strokes. Due to the proposed structure, we decreases leakage flux and increases electrodynamic force in comparison with structures of conventional vibrotactile actuators. Increased electrodynamic force can lift up the vibration amplitude according to each frequency, and then expand the frequency range. Optimal design of the flux path is another one of the most important factors to increase electrodynamic force in limited size. The length of initial air gap between the moving part including permanent magnets and the fixed part of soft magnetic materials with the solenoid coil is decided to increase the driving force and space-efficiency. We conceptuall...