Leopoldo Rossini Emmanuel Onillon Olivier Chételat Yves Perriard Back-EMF and rotor angular velocity estimation for a reaction sphere actuator. 334-339 2014 AIM https://doi.org/10.1109/AIM.2014.6878101 conf/aimech/2014 db/conf/aimech/aim2014.html#RossiniOCP14