“…As such, fault estimation is further needed for the purpose of active fault tolerant control. So far, considerable research attention has been devoted to the theoretical research on the fault estimation problem, and a variety of fault estimation approaches have been developed in existing literature, see e.g., Ding, 2008;Ertiame et al, 2015;Fekih and Seelem, 2015;Wei et al, 2013;Bouibed et al, 2014;Jiang et al, 2006;Yan and Edwards, 2007) and the references therein. For example, in (Jiang et al, 2006;Xu et al, 2012;Zhang et al, 2008), the problems of fault estimation have been investigated by applying adaptive fault diagnosis observers that can improve the rapidity of fault estimation.…”