“…Visual servoing (VS) has attracted more and more attention of researchers from various fields of robots, such as manipulators (Cai et al, 2013(Cai et al, , 2016Li and Zhao, 2017), mobile robots (Ke et al, 2017;Wang et al, 2009;Zhang et al, 2018), quadrotors (Islam et al, 2015;Thomas et al, 2016) and underwater vehicles (Gao et al, 2015(Gao et al, , 2017. VS control may be divided into two types in the light of the feedback signals of the closed-loop system: (1) position-based visual servoing (PBVS) (Park et al, 2012;Thuilot et al, 2002); (2) imagebased visual servoing (IBVS) (Tahri et al, 2013;Xie et al, 2009).…”