Mircea Badescu Sergiu Stroescu Stewart Sherrit Jack Aldrich Xiaoqi Bao Yoseph Bar-Cohen Zensheu Chang Wilson Hernandez Alaa Ibrahim Rotary hammer ultrasonic/sonic drill system. 602-607 2008 ICRA http://dx.doi.org/10.1109/ROBOT.2008.4543272 conf/icra/2008 db/conf/icra/icra2008.html#BadescuSSABBCHI08