Miniature impact actuator for haptic interaction with mobile devices

The crucial procedure in haptic interaction with mobile devices is to convey an appropriate haptic signal to a user according to the device’s condition. This haptic effect is achieved by creating vibrotactile signals with a large frequency bandwidth. However, it is quite challenging to generate vibrotactile signal with large frequency bandwidth in mobile devices because a vibration motor is fabricated to be embedded into the mobile devices. This paper presents a tiny vibrotactile actuator that can selectively stimulate human mechanoreceptors by creating a haptic signal with a large frequency bandwidth. To maximize the haptic effect in limited size, we simulate the magneto-motive force created by a solenoid by changing a wire diameter of the solenoid. In order to evaluate the haptic performance of the proposed actuator, we construct an experimental setup for measuring the force and the displacement of the proposed actuator. Using the experimental setup, the output force is measured by varying input current. The experiment clearly shows that the proposed actuator creates enough output force to stimulate human skin across a large frequency bandwidth and to convey a variety of vibrotactile sensations to users. The proposed actuator not only offers more reliable input than plain onscreen keypads in smaller spaces but also allows users to manipulate keypads more effectively.