Development and evaluation of an impact vibration actuator using an unstable mass for mobile devices

Abstract

The most important thing in haptic interaction with mobile devices is to create vibrotactile sensation with wide frequency range. However, it is not easy to generate vibrotactile signal with wide frequency range with conventional vibrotactile actuators. Therefore, this paper presents a miniature impact type actuator, which has wide enough frequency range to selectively stimulate mechanoreceptors, consisting of a mass, an elastic spring, a housing, and a solenoid. To create strong impact force in wide frequency range in real-time, we adopt an unstable structure. Due to the impact with fast rising and falling time in the proposed vibration actuator, strong impact vibration can be created over wide frequency range. We simulate the magnetic flux line of the proposed actuator and magnetic force applied to the mass using an FEM simulation tool. We carry out an experiment in order to investigate the response time of the proposed actuator. Another experiment is conducted to show that the proposed actuator can create sufficient output force to stimulate human skin over a wide frequency bandwidth and can convey a variety of vibrotactile sensations to users.