Masataka Niwa Haruo Noma Kenichi Hosaka Yasuyuki Yanagida Robert W. Lindeman Controlling the Perceived Vibrational Frequency and Amplitude of a Voice-Coil-Type Tactor. 7 2006 conf/haptics/2006 HAPTICS http://doi.ieeecomputersociety.org/10.1109/VR.2006.39 db/conf/haptics/haptics2006.html#NiwaNHYL06