Yi Feng 0002 Zhigang Zhu Jizhong Xiao Self-localization of a heterogeneous multi-robot team in constrained 3D space. 1343-1350 2007 IROS http://dx.doi.org/10.1109/IROS.2007.4399320 conf/iros/2007 db/conf/iros/iros2007.html#FengZX07