Norisuke Fujii Tsai-Lin Chou Jun Ota Rearrangement task realization by multiple mobile robots with efficient calculation of task constraints. 8-13 2007 conf/icra/2007 ICRA http://dx.doi.org/10.1109/ROBOT.2007.363757 db/conf/icra/icra2007.html#FujiiCO07