Ali Jazayeri Mahdi Tavakoli Revisiting Llewellyn's absolute stability criterion for bilateral teleoperation systems under non-passive operator or environment. 70-75 2012 IROS https://doi.org/10.1109/IROS.2012.6385949 conf/iros/2012 db/conf/iros/iros2012.html#JazayeriT12