Novel linear impact-resonant actuator for mobile applications

•The actuator was optimized to maximize the impact force.•It was designed with limited size (11mm×9mm×3.2mm) to be embedded into mobile device.•It operated at a driving voltage of 3.3V, consuming 0.3W.•It generated impact vibration greater than 2g in a broad frequency range of 1–210Hz.•Its response time was 4ms, which was about five times faster than commercial LRA. In this study, a novel linear impact-resonant actuator was proposed for mobile device applications. The most significant issue in mobile haptic actuators is the ability to provide various vibrotactile and alert functions despite their size and power consumption limitations. This study aimed to achieve fast and strong impact vibrations over a wide frequency range, including the resonant frequency, which decoupled the intensity and frequency of the vibration to achieve both fruitful vibrotactile feedback and strong alarming vibration. To accomplish this, a new mechanism was proposed that can amplify the impact force at the end of the stroke and increase the speed of the response. The magnetic flux path was optimized using an equivalent magnetic circuit model to maximize the electromagnetic force. The performance of a prototype actuator (11mm×9mm×3.2mm) was evaluated in terms of the response time and vibration acceleration amplitude under an input power of 0.3W. The experimental results clearly showed that the proposed actuator could create a vibration acceleration that was greater than 2g over a frequency range of 1–210Hz with a fast response of 4ms and extremely short residual vibration. In addition, a stronger impact force of around 3g could be generated near the resonant frequency of 190Hz.