Abstract
Recently, haptic feedback has been an issue in mobile devices with a touch screen. The haptic feedback plays a role in generating button sensation on the touch screen. For the haptic feedback, vibration motors have been widely used, because they are small enough to be equipped into the mobile devices. However, commercial vibration motor is not able to create various haptic sensations. For the generation of a wide variety of tactile sensations, this paper proposes a smart actuator with actuating and sensing function. This actuator is composed of a solenoid, a permanent magnet, and an elastic beam covered with piezoelectric material. When electric cur rent is applied into the solenoid, the electromagnetic force by solenoid bends the elastic beam covered with piezoelectric material. This mechanism causes the direct piezoelectric effect of the piezoelectric material, and the electric signal is created from the piezoelectric material. The stroke of the proposed smart actuator can be estimated from the electric signal. The estimated stroke is used as a signal for feedback control. By feedback control using electric signal from the smart actuator, unwanted aftershocks of vibration can be reduced. The vibration signal without aftershocks conveys more crispy sensation to users, and it can generate various haptic patterns.